DESCRIPTION
INFORMATION PROCESSING APPARATUS, METHOD, AND PROGRAM
TECHNICAL FIELD
5 [OOOl]
The present invention relates to an information
processing apparatus; a method, and a program, and
especially relates to an information processing apparatus,
a method, and a program that are capable * of suppressing
10 deterioration of content quality.
BACKGROUND ART
[0002]
In recent years, there has been a growing demand
15 for transmission of multimedia data with a low delay
while performing media reference signal synchronization
(so-called "GENLOCK synchronization") via the internet, a
local area network (LAN), or other transmission line.
[0003]
20 For example, there is a system in which a camera
and its control unit (so-called "camera control unit"
(CCU)) are connected with a high definition serial
digital interface (HD-SDI) cable and uncompressed
synchronization transmission is performed in a
25 broadcasting station. In recent years, the HD-SDI cable
of this system has been replaced with an Ethernet
(trademark) cable and the transmission has been performed
on the Ethernet (trademark) while performing GENLOCK
synchronization with an IP packet.
30 [0004]
For such a purpose, when IP transmission of
multimedia data is performed, the usability is required,
which is equivalent to that of the transmission via the
HD-SDI cable. Therefore, highly accurate GENLOCK
synchronization and low delay transmission equal to or
5 less than a video frame interval are required.
[0005]
In response to the request, a system is proposed in
which every several numbers of lines of each picture of a
moving image is encoded as one encoding block (a line
10 block) by wavelet transformation (for example, see Patent
Document 1) .
[0006]
In this system, the encoding is started without
waiting an input of all of data in a picture. Therefore,
15 when generated encoded data is transmitted via a network
and is decoded at a reception side, a decoding process
can be started before receiving all of the data in the
picture. That is, if a network propagation delay is
substantially small, real time (instantaneous) moving
20 image transmission with a delay equal to or less than the
frame interval becomes possible.
[0007]
In such data transmission, it is necessary for a
reception device to buffer (temporarily hold) received
25 data in order to deal with a delay in an encoding process,
in a data transmission process, in a QoS control process,
and the like. In other words, setting of the encoding
process, the QoS control process, and the like is
performed (not to overflow) in accordance with a buffer
30 time at a receiving side. That is, image quality of
decoded image or transmission quality depends on the
buffer time.
[0008]
By the way, in a conventional system, when data is
transmitted by this data transmission from a plurality of
5 transmission devices to one reception device, reception
buffer times with respect to the transmission devices are
set independently of each other, or, are set to be a
predetermined time (a common reception buffer time is
used).
10
CITATION LIST
PATENT DOCUMENT
[0009]
Patent Document 1: Japanese Patent No. 4371120
15
SUMMARY OF THE INVENTION
PROBLEMS TO BE SOLVED BY THE INVENTION
[OOlO]
However, typically, delays (transmission delays) in
20 relation to the data transmission from the transmission
devices often differ from each other because a line, a
band width, and the like of the data transmission differ
from each other. However, in a case of a conventional
system, the setting of a reception buffer time is carried
25 out without considering the difference of the
transmission delays (the settings are done independently
of each other or are commonly set).
[ 0 0 11 ]
As described above, the setting of encoding,
30 control of QoS, and the like is performed based on the
reception buffer time. Therefore, in practice, even in a
case where reception data is held longer than the
reception buffer time, there is a concern that the image
quality of a decoded image or the transmission quality
cannot be improved. That is, there is a concern of
5 causing an unnecessary waiting time. In other word,
there is a concern that the content quality is
unnecessarily deteriorated by the data transmission.
[0012]
The present invention has been made in view of the
10 foregoing, and a purpose of the invention is to use a
spare time of each process for improving the image
quality and the transmission quality and to decrease an
unnecessary delay time.
15 SOLUTIONS TO PROBLEMS
[0013]
One aspect of the present invention is an
information processing apparatus, including: an
adjustment means configured to adjust, in data
20 transmission for transmitting mutually synchronized data
from a plurality of transmission devices to a reception
device, a reception buffer time that is a buffer time for
synchronizing each of the data in the reception device
and is set for each of the data transmission using a
25 difference in transmission delays that are a delay time
generated in a transmission line of each of the data
transmission; and a setting means configured to set a
parameter of a process in relation to each of the data
transmission using the reception buffer time adjusted by
30 the adjustment means.
[0014]
The adjustment means may obtain a maximum value of
the transmission delays, and obtain the reception buffer
time by adding a difference between the transmission
delay of each of the data and the maximum value to a
5 prescribed reception buffer time that is a predetermined
reception buffer time.
[ 00151
The process in relation to the data transmission
may be a QoS control process of the data transmission,
10 and the setting means may set, as the parameter of the
QoS control process, a redundant encoding block reception
waiting time that is a time from when a head packet of a
redundant encoding block is received until a tailing
packet of the redundant encoding block is received, a
15 retransmission packet waiting time that is a time for
waiting a retransmission packet, and a network jitter
handling buffer time for absorbing a network jitter.
[0016]
The data may be encoded in a transmission source,
20 obtained encoded data may be transmitted, and the encoded
data may be decoded in a transmission destination, and
the setting means may set, as the parameter of the
process, a variable compression encoding delay request
time necessary when the encoded data rate-controlled and
25 generated at the encoding is subjected to smoothingtransmission.
[0017]
The information processing apparatus may further
include: a reception means configured to receive an image
30 quality request that is a request in relation to image
quality of the data and a transmission quality request
that is a request in relation to transmission quality in
the data transmission, wherein the adjustment means may
adjust the reception buffer time based on the image
quality request and the transmission quality request
5 received by the reception means.
[0018]
The adjustment means may set a provisional
reception buffer time based on the image quality request
and the transmission quality request received by the
10 reception means, and adjust the reception buffer time
based on the provisional reception buffer time.
[0019]
The information processing apparatus may further
include: an output means configured to display a GUI
15 supporting an input of the image quality request and the
transmission quality request received by the reception
means.
[0020]
One aspect of the present invention is an
20 information processing method to be performed by an
information processing apparatus, including: in data
transmission for transmitting mutually synchronized data
from a plurality of transmission devices to a reception
device, adjusting, by an adjustment means of the
25 information processing apparatus, a reception buffer time
that is a buffer time for synchronizing each of the data
in the reception device and is set for each of the data
transmission using a difference in transmission delays
that are a delay time generated in a transmission line of
30 each of the data transmission; and setting, by a setting
means of the information processing apparatus, a
parameter of a process in relation to each of the data
transmission using the adjusted reception buffer time.
[0021]
Further, one aspect of the present invention is a
5 program for causing a computer, which performs data
transmission, to function as: an adjustment means that
adjusts, in data transmission for transmitting mutually
synchronized data from a plurality of transmission
devices to a reception device, a reception buffer time,
10 which is a buffer time for synchronizing each of the data
in the reception device and is set for each of the data
transmission, using a difference in transmission delays
that are a delay time generated in a transmission line of
each of the data transmission; and a setting means that
15 sets a parameter of a process in relation to each of the
data transmission using the reception buffer time
adjusted by the adjustment means.
[0022]
In one aspect of the present invention, in data
20 transmission for transmitting mutually synchronized data
from a plurality of transmission devices to a reception
device, a reception buffer time, which is a buffer time
for synchronizing each of the data in the reception
device and is set for each of the data transmission, is
25 adjusted using a difference in transmission delays that
are a delay time generated in a transmission line of each
of the data transmission; and a parameter of a process in
relation to each of the data transmission is set using
the adjusted reception buffer time.
30
EFFECTS OF THE INVENTION
[0023]
According to the present invention, data can be
transmitted. Especially, deterioration of content
quality can be suppressed.
BRIEF DESCRIPTION OF DRAWINGS
[0024]
Fig. 1 is a block diagram showing a main
configuration example of a transmission system to which
10 the present invention is applied.
Fig. 2 is a block diagram showing a main
configuration example of a transmission device.
Fig. 3 is a block diagram showing a main
configuration of an encoding unit.
15 Fig. 4 is a diagram describing an outline of
analysis filtering.
Fig. 5 is a diagram following Fig. 3 describing the
outline of the analysis filtering.
Fig. 6 is a diagram describing a line block.
Fig. 7 is a block diagram showing a main
configuration example of a reception unit.
Fig. 8 is a block diagram showing a main
configuration example of a decoding unit.
Fig. 9 is a flowchart describing an example of a
25 flow of a whole data transmission process.
Fig. 10 is a flowchart describing an example of a
flow of a reception buffer time determination process.
Fig. 11 is a diagram showing an example of a look
of setting of a reception buffer time.
30 Fig. 12 is a flowchart describing an example of a
flow of a reception buffer time/processing parameter
setting process.
Fig. 13 is a block diagram showing a main
configuration of a transmission system to which the
present invention is applied.
5 Fig. 14 is a diagram showing a display example of a
request reception screen.
Fig. 15 is a flowchart describing another example
of a flow of a data transmission process.
Fig. 16 is a flowchart describing an example of a
10 flow of a reception buffer time determination process.
Fig. 17 is a flowchart following Fig. 16 describing
the example of the flow of the reception buffer time
determination process.
Fig. 18 is a flowchart describing an example of a
15 flow of a reception buffer dynamic change transmission
process.
Fig. 19 is a block diagram showing a main
configuration of a personal computer to which the present
invention is applied.
20
MODE FOR CARRYING OUT THE INVENTION
[0025]
Modes for carrying out the invention (hereinafter,
referred to as embodiments) will be herein described.
25 Note that description will be given in the following
order.
1. First embodiment (transmission system)
2. Second embodiment (transmission system)
3. Third embodiment (personal computer)
30 100261
<1. First embodiment>
[An outline of a transmission system]
Fig. 1 is a block diagram showing a main
configuration example of a transmission system to which
the present invention is applied. A transmission system
5 100 is a system that transmits image data from a
plurality of transmission devices (transmission devices
101-1 to 101-N (N is an integer equal to or more than 2))
to a reception device 103 via a network 102 that is a
general purpose transmission line such as the internet
10 and a LAN. Hereinafter, in a case where it is not
necessary to describe the transmission devices to
distinguish from one another, the transmission devices
are simply referred to as the transmission device 101.
Note that the network 102 includes not only a cable and
15 the like, but also a device such as a router and a hub.
[0027]
Image data (video data) input to each transmission
device 101 is transmitted to the reception device 103 via
the network 102 in real time (instantaneously) and is
20 output from the reception device 103. That is, the video
data input to each transmission device 101 with a
predetermined frame rate (for example, a frame rate at
normal reproduction) is encoded in the transmission
device 101, is transmitted to the reception device 103 as
25 encoded data, is decoded in the reception device 103, and
is output from the reception device 103 at a
predetermined frame rate (for example, a frame rate at
normal reproduction) with a predetermined delay time.
[0028]
30 The reception device 103 synthesizes data from the
transmission devices 101 in synchronization with each
other and outputs (reproduces) it. That is, data
transmission from each transmission device 101 is
performed not to deteriorate such synchronization
reproduction.
5 [0029]
In recent years, there has been a growing demand
for transmitting multimedia data with a low delay while
performing media reference signal synchronization (socalled
"GENLOCK synchronization") via a general-purpose
10 transmission line such as the internet and a local area
network (LAN).
[0030]
For example, in a broadcasting station, a camera
and its control unit (so-called "camera control unit"
15 (CCU)) are connected with an HD-SDI cable and
uncompressed synchronization transmission is performed
therebetween. In recent years, this HD-SDI cable has
been replaced with an Ethernet (trademark) cable and the
transmission has been performed on the Ethernet
20 (trademark) while performing GENLOCK synchronization with
an IP packet.
[0031]
For such a purpose, when IP transmission of
multimedia data is performed, the usability equivalent to
25 that of the transmission via the HD-SDI cable is required.
Therefore, highly accurate GENLOCK synchronization and
low delay transmission equal to or less than a video
frame interval or less are required.
[0032]
30 To respond to the request, the Patent Document 1
proposes a system of encoding every several numbers of
lines of each picture of a moving image as one encoding
block (a line block). In this system, the transmission
device 101 is capable of starting the encoding without
waiting an input of all of data in the picture. Also,
5 the transmission device 101 is capable of sequentially
transmitting encoded data obtained by the encoding to the
reception device 103 via the network 102.
[0033]
Further, the reception device 103 is capable of
10 starting decoding before receiving all of data in the
picture. If a transmission delay of the network 102 (a
delay generated in the network 102 in the data
transmission from the transmission device 101 to the
reception device 103) is sufficiently small, real-time
15 moving image transmission with a delay equal to or less
than a frame interval (data transmission capable of
outputting from the reception device 103 with a frame
rate at the input timing to the transmission device 101)
becomes possible.
20 [0034]
When stream data is transmitted from a plurality of
transmission devices and a synchronization process is
performed in a reception device, conventionally, the
synchronization process has been realized by providing a
25 reception buffer in a reception unit within the reception
device corresponding to each transmission device and by
setting a different reception buffer time for the
synchronization process.
[0035]
30 However, in the previous system, a parameter in an
encoding process or in a QoS control process has not been
changed in accordance with the reception buffer time and
a difference between the reception buffer times of the
reception units corresponding to the plurality of
transmission devices.
5 100361
Therefore, although there is no chance of
increasing the transmission delay by adjusting the
parameter in the encoding process or in the QoS control
process, the transmission delay has not been adjusted,
10 and therefore, a waste of the delay time is caused.
[0037]
As described above, the transmission system 100 is
capable of improving the image quality and picture
quality without increasing the delay time by adjusting
15 the parameter in the encoding process, the QoS control
process, and the like in each data transmission in
accordance with the difference in length of the
transmission delay.
[0038]
20 As shown in Fig. 1, the reception device 103
includes a transmission unit 111, a reference signal
synchronization unit 112, a reception units 113-1 to 113-
N, an integrated reception buffer time adjustment unit
114, and a synthesis unit 115.
25 [0039]
The transmission unit 111 communicates with each
transmission device 101, transmits information supplied
from the reference signal synchronization unit 112 and
the reception units 113-1 to 113-N, and receives
30 information supplied from each transmission device 101
and supplies the information to the reference signal
synchronization unit 112 and the reception units 113-1 to
113-N.
[0040]
The reference signal synchronization unit 112
5 communicates with the transmission device 101 via the
transmission unit 111 and synchronizes a reference signal
with the transmission device 101. The reference signal
is a signal used for synchronizing a process between the
transmission device 101 and the reception device 103. A
10 synchronized reference signal is supplied to the
reception units 113-1 to 113-N.
[0041]
That is, (the reference signal synchronization unit
112) of the reception device 103 serves as a master and
15 all of the transmission devices 101 synchronize with the
reception device 103, whereby all of the transmissiondevices
101 can synchronize with the reception device 103,
accordingly.
[0042]
20 The reception units 113-1 to 113-N respectively
correspond to the transmission devices 101-1 to 101-N,
receive an RTP packet supplied from the corresponding
transmission devices 101, decode the RTP packet, and
output video data. Hereinafter, in a case where it is
25 not necessary to describe the reception units 113-1 to
113-N to distinguish from one another, the reception
devices are simply referred to as the reception unit 113.
That is, the reception units 113, the number thereof
being equal to or larger than the number of the
30 transmission devices 101, are prepared in advance. In
other word, the reception device 103 is capable of
receiving packets transmitted from the transmission
devices 101, the number thereof being equal to or smaller
than the number of the built-in reception units 113.
COO431
5 The integrated reception buffer time adjustment
unit 114 adjusts a reception buffer time of each
reception unit 113. The synthesis unit 115 synthesizes
the video data output from each reception unit 113 and
outputs synthesized video data from a video output
10 terminal "video OUT" of the recepti,on device 103.
Timings of outputting the video data of the reception
units 113 are in synchronization with each other. The
synthesis unit 115 properly synchronizes these video data
based on a user instruction and the like, for example,
15 and outputs the data.
[0044]
[A configuration of a transmission device]
As shown in Fig. 2, the transmission device 101
includes an encoding unit 131, a forward error correction
20 (FEC) unit 132, a real-time transport protocol (RTP) unit
133, a smoothing unit 134, a reference signal
synchronization unit 135, a media synchronization unit
136, an RTP control protocol (RTCP) unit 137, an auto
repeat request (ARQ) unit 138, and a reception buffer
25 time/processing parameter setting unit 139.
[0045]
Video data (moving image data) input from a video
input IF "video IN" via a video camera and the like is
supplied to the encoding unit 131. The encoding unit 131
30 performs an encoding process of the moving image data
with a predetermined encoding system. This encoding
system employs any system but a system with a lower delay
is desirable. An example of the encoding system will be
described below.
[0046]
5 The encoding unit 131 includes a rate control unit
141. The rate control unit 141 controls a bit rate of
encoded data generated in the encoding unit 131. The
encoding unit 131 performs RTP-packetization of the
generated encoded data and supplies it to the FEC unit
10 132.
[0047]
The FEC unit 132 generates a redundant packet of
the RTP packet supplied from the encoding unit 131. The
RTP unit 133 performs the RTP-packetization of the
15 redundant packet of the encoded data supplied from the
FEC unit 132.
[0048]
The smoothing unit 134 temporarily holds the RTP
packet supplied from the RTP unit 133, smoothes it into a
20 predetermined data rate and transmits it.
[0049]
The reference signal synchronization unit 135
communicates with the reference signal synchronization
unit 112 of the reception device 103 as a destination via
25 the network 102 and synchronizes a reference signal clock
The reference signal synchronization unit 135 supplies a
reference signal that has been synchronized with the
reception device 103 to the media synchronization unit
136.
30 [0050]
The media synchronization unit 136 supplies, to the
encoding unit 131 (an RTP unit in the encoding unit 131)
and the RTP unit 133, a time in synchronization with a
sampling time of data input to the video IN, where a time
supplied from the reference signal synchronization unit
5 135 is a reference. This supplied time is added to the
RTP packet as an RTP time stamp.
[0051]
The RTCP unit 137 performs transference/acceptance
of an RTCP message with the reception device 103 as a
10 destination and performs transmission/reception of a
control message (QoS (quality of service) control
message) for a QoS control process. The RTCP unit 137
supplies an acquired control message to the ARQ unit 138
and the reception buffer time/processing parameter
15 setting unit 139.
[0052]
The ARQ unit 138 controls the smoothing unit 134
according to a retransmission request message supplied
from the RTCP unit 137 and retransmits a requested RTP
20 packet.
[0053]
The reception buffer time/processing parameter
setting unit 139 performs parameter setting of the
encoding unit 131 and the FEC unit 132 according to
25 setting of various delay times and the like supplied from
the RTCP unit 137.
[0054]
[A configuration example of an encoding unit]
Next, an example of the encoding unit 131 of the
30 transmission device 101 will be described. Fig. 3 is a
block diagram showing a configuration example of the
encoding unit 131 of the transmission device 101. The
encoding unit 131 performs hierarchical encoding of the
image data in which the image data is subjected to
hierarchization in order of importance with respect to
5 resolution and is encoded for each hierarchy. For
example, the encoding unit 131 generates hierarchized
data in order of importance with respect to spatial
resolution. Also, for example, the encoding unit 131
generates the hierarchized data in order of importance
10 with respect to resolution in a time direction. Further,
for example, the encoding unit 131 generates the
hierarchized data in order of importance with respect to
a signal to noise ratio (SNR). The encoding unit 131
encodes hierarchized data generated in this way for each
15 hierarchy.
[0055]
As such hierarchical encoding, for example, there
is a joint photographic experts group (JPEG) 2000 system
in which each picture of moving image data is subjected
20 to wavelet transformation and entropy encoding. Although
any hierarchical encoding method can be employed,
hereinafter a case will be described in which the
encoding unit 131 performs the wavelet transformation of
the moving image data for each plurality of lines and
25 performs the entropy encoding.
[0056]
As shown in Fig. 3, the encoding unit 131 includes
a wavelet transformation unit 161, a quantization unit
162, an entropy encoding unit 163, a rate control unit
30 141, and an RTP unit 164. The wavelet transformation
unit 161 performs the wavelet transformation of each
picture of a moving image for each plurality of lines.
[0057]
The wavelet transformation is a process in which an
analysis filter process for dividing input data into a
5 low-band component and a high-band component is performed
for both in a horizontal direction of a screen and in a
vertical direction of the screen. That is, the input
data is divided into four components (subbands) by the
wavelet transformation process: a component low-band in
10 the horizontal direction and low-band in the vertical
direction (LL component), a component high-band in the
horizontal direction and low-band in the vertical
direction (HL component), a component low-band in the
horizontal direction and high-band in the vertical
15 direction (LH component), and a component high-band in
the horizontal direction and high-band in the vertical
direction (HH component).
[0058]
The wavelet transformation unit 161 recursively
20 repeats such a wavelet transformation process of the
component low-band in the horizontal direction and lowband
in the vertical direction (LL component) obtained by
the analysis filter process for a predetermined number of
times. That is, each picture of the moving image data is
25 divided into a hierarchized plurality of subbands
(frequency components) (hierarchized data is generated)
by the wavelet transformation process. The entropy
encoding unit 163 performs the encoding for each subband.
[0059]
30 The image data of each picture of the moving image
is input into the wavelet transformation unit 161 one
line at a time in the order from the top to the bottom of
the image. Also, the image data of each line is input
one sample (one column) at a time in the order from the
left to the right of the image.
5 [0060]
The wavelet transformation unit 161 executes
analysis filtering in the horizontal direction of the
image (horizontal analysis filtering) of the input image
data every time the number of sample data with which the
10 analysis filtering is executable is acquired (on
reception of the data). For example, the wavelet
transformation unit 161 performs the horizontal analysis
filtering of image data 181 of a baseband shown in the
left of Fig. 4 every time M column is input, and divides
15 the image data 181 into a low-band component (L) and a
high-band component (H) in the horizontal direction one
line at a time. A horizontal analysis filter process
result 182 shown in the right of Fig. 4 shows the lowband
component (L) and the high-band component (H) in the
20 horizontal direction of N lines divided by the wavelet
transformation unit 161.
[0061]
Next, the wavelet transformation unit 161 performs
analysis filtering in the vertical direction (vertical
25 analysis filtering) of each component of the horizontal
analysis filter process result 182. The wavelet
transformation unit 161 performs, when coefficients of
vertical lines necessary for the vertical analysis
filtering are generated by the horizontal analysis
30 filtering, the vertical analysis filtering of the
coefficients of the vertical lines necessary for the
vertical analysis filtering for each column.
[0062]
As a result, the horizontal analysis filter process
result 182 is, as shown in the left of Fig. 5, divided
5 into wavelet transformation coefficients (hereinafter,
referred to as coefficients) of four components
(hierarchized data 183): a component low-band both in the
horizontal direction and in the vertical direction (LL
component), a component high-band in the horizontal
10 direction and low-band in the vertical direction (HL
component), a component low-band in the horizontal
direction and high-band in the vertical direction (LH
component), and a component high-band both in the
horizontal direction and in the vertical direction (HH
15 component) .
[0063]
Until coefficients of a predetermined hierarchy
(division level) are obtained, the HL component, the LH
component, and the HH component among the obtained
20 analysis filtering result are output outside. The
remaining LL component is subjected to the analysis
filtering again by the wavelet transformation unit 161.
That is, for example, the hierarchized data 183 shown in
the left of Fig. 5 is transformed into hierarchized data
25 184 shown in the right of Fig. 5. In the hierarchized
data 184, four components: an LLLL component, an LLHL
component, an LLLH component, and an LLHH component are
generated from the LL component.
[0064]
30 The wavelet transformation unit 161 recursively
performs such analysis filtering the predetermined number
of times, and generates hierarchized data obtained by
hierarchizing the moving image data into a desired
division level. Fig. 6 is a diagram of an example of the
hierarchized data hierarchized into a division level 3
5 (third hierarchy). In Fig. 6, hierarchized data 185
divided into the division level 3 is composed of
subbands: a 3HL component, a 3LH component, and a 3HH
component of a division level 1 (hierarchy number 3 ) , a
2HL component, a 2LH component, and a 2HH component of a
10 division level 2 (hierarchy number 2), and a ILL
component, a 1HL component, a 1LH component, and a 1HH
component of a division level 3 (hierarchy number 1).
[0065]
In the wavelet transformation process, the number
15 of lines to be generated becomes smaller by one half of
the power of two every time the filtering process is
repeated (every time the hierarchy goes into a lower
level). The number of base band lines necessary for
generating coefficients of one line of a final division
20 level (hierarchy number 1) are determined according to
the number of repetition of the filtering process (the
number of hierarchies of the final division level).
Typically, the number of hierarchies is determined in
advance.
25 [0066]
The image data of the baseband (image data of
several lines) necessary for generating the coefficients
of one line of the final division level or the
coefficients of each hierarchy are collectively referred
30 to as a line block (or a precinct).
[0067]
A portion shown in a slant line in Fig. 6
represents coefficients that constitute one line block.
As shown in Fig. 6, the line block is composed of the
coefficients of one line of each component of the
5 hierarchy number 1, the coefficients of two lines of each
component of the hierarchy number 2, and the coefficients
of four lines of each component of the hierarchy number 3.
Note that the image data before the analysis filtering
equivalent to the above, that is, the image data of eight
10 lines in this example is also referred to as a line block
(or a precinct).
[0068]
Referring back to Fig. 3, the quantization unit 162
performs quantization by subtracting the coefficients of
15 each component generated by the wavelet transformation
unit 161 by a quantization step size, for example, to
generate quantization coefficients. At this time, the
quantization unit 162 can set the quantization step size
for each line block (precinct). This line block includes
20 the coefficients of all of the frequency components of a
certain image region (in the case of Fig. 6, ten
frequency components from ILL to 3HH). Therefore, an
advantage of multi-resolution analysis, which is a
characteristic of the wavelet transformation, can be
25 fully utilized by performing the quantization for each
line block. Also, because only the number of line blocks
is determined in all of the screens, a load of the
quantization can be kept small.
[0069]
30 Further, energy of an image signal is typically
concentrated in a low-band component and there is a
characteristic that deterioration of the low-band
component is easily noticeable in human vision.
Therefore, it is effective to perform weighing at the
time of quantization in such a way that the quantization
5 step size in the subbands of the low-band components
results in a small value. By this weighing, a relatively
large information amount is allocated to the low-band
component, and therefore, overall subjective image
quality is improved.
10 [0070]
The entropy encoding unit 163 performs sourcecoding
of the quantization coefficients generated in the
quantization unit 162, generates compressed encoded data,
and supplies it to the rate control unit 141. As the
15 source-coding, for example, Huffman coding used in JPEG
system or a moving picture experts group (MPEG) system or
a higher precise arithmetic coding used in JPEG 2000
system can be used.
[0071]
20 Here, which range of coefficients should be
subjected to entropy encoding is very important element
directly related to compression efficiency. For example,
in JPEG system or MPEG system, 8 x 8 blocks are subjected
to discrete cosine transform (DCT), and generated 64 DCT
25 transformation coefficients are subjected to Huffman
coding, whereby information is compressed. That is, the
64 DCT transformation coefficients are the range of the
entropy encoding.
100721
30 Unlike the DCT transformation in relation to the 8
x 8 blocks, the wavelet transformation unit 161 performs
the wavelet transformation by line. Therefore, the
entropy encoding unit 163 performs source-coding
independently for each frequency band (subband), and for
each P line in each frequency band.
5 [0073]
In P, one line is the minimum line. The smaller
number of lines needs less reference information, and .
therefore, a memory capacity can be reduced. On the
other hand, if the number of lines is large, the
10 information amount also increases. Therefore, the
encoding efficiency can be improved. However, P has a
value exceeding the number of lines of a line block in
each frequency band, it becomes necessary to have a line
of the next line block. Therefore, it is necessary to
15 wait until quantization coefficient data of this line
block is generated by the wavelet transformation and the
quantization, and therefore, this waiting time becomes a
delay time.
[0074]
20 Therefore, to realize a low delay, it is necessary
that P is equal to or smaller than the number of lines of
the line block. For example, in the example of Fig. 6,
for the frequency bands of ILL, lHL, lLH, and lHH, P = 1
because the number of lines of the line block = 1 line.
25 Also, for the subbands of 2HL, 2LH, and 2HH, P = 1 or 2
because the number of lines of the line block = 2 lines.
[0075]
The rate control unit 141 finally performs control
of adjusting a rate to a target bit rate or compression
30 rate, and supplies encoded data after the rate control to
the RTP unit 164. For example, the rate control unit 141
compares a bit rate (compression rate) of encoded data
output from the entropy encoding unit 163 with a target
value, and transmits a control signal to the quantization
unit 162 so as to decrease the quantization step size in
5 order to increase the bit rate and to increase the
quantization step size in order to decrease the bit rate.
[0076]
The RTP unit 164 performs RTP-packetization of the
encoded data supplied from the rate control unit 141 and
10 supplies it to the FEC unit 132.
LO0771
[A configuration of a reception device]
Next, a configuration example of an interior of
each reception unit 113 of the reception device 103 in
15 Fig. 1 will be described. Fig. 7 is a block diagram
showing a main configuration example of the reception
unit 113. As shown in Fig. 7, the reception unit 113
includes a reception unit 201, a reception buffer 202, an
RTP unit 203, an FEC unit 204, a decoding unit 205, an
20 ARQ unit 206, an RTCP unit 207, a reception buffer time
setting unit 208, and a media synchronization unit 210.
[0078]
The reception unit 201 receives an RTP packet
transmitted from the transmission device 101
25 corresponding thereto via the network 102 and supplied
via the transmission unit 111, and supplies the RTP
packet to the reception buffer 202. The reception buffer
202 temporarily holds the RTP packet supplied from the
reception unit 201 in order to synchronize with data
30 transmission by other reception units 113, for example,
and then supplies the RTP packet to the RTP unit 203 at a
time determined based on information from the reception
buffer time setting unit 208 and the media
synchronization unit 210.
[0079]
5 The RTP unit 203 reconfigures the RTP packet to
generate FEC redundant encoded data, which is encoded
data including a redundant packet, and supplies it to the
FEC 204. The FEC unit 204 detects a loss of the packet
and recovers lost packet data by a redundant-encoding
10 decoding process as needed. The FEC unit 204 supplies
processed encoded data to the decoding unit 205.
[0080]
The decoding unit 205 decodes the encoded data by a
decoding system corresponding to a system of the encoding
15 process in the encoding unit 131. Decoded video data
(moving image data) is output from a video output IF
(video OUT) of the reception device 103 to a picture
display device such as a display (not shown), for example.
[0081]
20 The ARQ unit 206 detects a lost packet (a packet
that could not be received) in the reception unit 201,
and controls the RTCP unit 207 to transmit a
retransmission request message to the ARQ unit 138 of the
transmission device 101 when detecting the lost packet.
25 The RTCP unit 207 supplies the retransmission request
message requested by the ARQ unit 206 and various types
of setting information supplied from the reception buffer
time setting unit 208 as an RTCP message to the RTCP unit
137 of the transmission device 101.
30 [0082]
The reception buffer time setting unit 208 sets and
adjusts a reception buffer time based on control and the
l i k e by the integrated reception buffer time adjustment
unit 1 1 4 .
[ 0 0 8 3 ]
5 The media synchronization u n i t 210 controls an
output timing of the RTP packet from the reception buffer
202, a s t a r t timing of a decoding process i n the decoding
unit 205, and the l i k e based on the reference signal
synchronized i n each reception u n i t 113 (and each
10 transmission device 101) by the reference signal
synchronization unit 112.
[0084]
[A configuration example of a decoding u n i t ]
Next, an example of the decoding u n i t 205
15 corresponding t o the above-described example of the
encoding unit 131 w i l l be described. Fig. 8 is a block
diagram showing a configuration example of the decoding
unit 205 of the reception u n i t 113. In Fig. 8, the
decoding unit 205 includes an RTP u n i t 230, an entropy
20 decoding unit 231, an inverse quantization unit 232, and
a wavelet inverse transformation u n i t 233.
[0085]
The RTP unit 230 transforms the RTP packet supplied
from the FEC unit 204 i n t o encoded data and supplies it
25 t o the entropy decoding unit 231. The entropy decoding
unit 231 decodes the encoded data by a method
corresponding to the encoding method i n the entropy
encoding unit 163 and generates quantization coefficient
data. For example, Huffman decoding, high e f f i c i e n t
30 arithmetic decoding, and the l i k e can be used. Note t h a t ,
i n a case where decoding has been performed for each P
line in the entropy encoding unit 163, the entropy
decoding unit 231 independently decodes each subband and
performs decoding for each P line within each subband.
[0086]
5 The inverse quantization unit 232 performs inverse
quantization by multiplying the quantization coefficient
data and the quantization step size to generate
coefficient data. This quantization step size is,
typically, specified in a header of the encoded data
10 supplied from the transmission device 101. Note that, in
a case where the quantization step size is set for each
line block in the quantization unit 162, an inverse
quantization step size is similarly set for each line
block in the inverse quantization unit 232, and inverse
15 quantization is performed.
100871
The wavelet inverse transformation unit 233
performs an inverse process of the wavelet transformation
unit 161. That is, the wavelet inverse transformation
20 unit 233 performs a filtering process (synthesis
filtering process) that synthesizes a low-band component
and a high-band component both in the horizontal
direction and in the vertical direction with respect to
the coefficient data divided into a plurality of
25 frequency bands by the wavelet transformation unit 161.
The wavelet inverse transformation unit 233 restores
video data of a baseband by such a wavelet inverse
transformation process, and outputs it from the video OUT
to an outside of the reception device 103.
30 [0088]
Obviously, the above-described encoding unit 131
and the decoding unit 205 are an example, and other
encoding/decoding system may be used.
[0089]
[A transmission process]
5 Next, each process performed in the transmission
system 100 (Fig. 1) will be described. First, a
transmission process for transmitting video data from
each transmission device 101 to the reception device 103
via the network 102 will be described.
10 [0090]
The transmission device 101 inputs video data input
from the video input IF "video IN" via a video camera and
the like to the encoding unit 131 (Fig. 2) that performs
a compression encoding process of moving image data and
15 performs encoding.
[0091]
Encoded data generated by this encoding is
subjected to an RTP packetization process by the RTP unit
164 (Fig. 3) within the encoding unit 131, and is
20 supplied to the FEC unit 132 (Fig. 2) as an RTP packet.
The FEC unit 132 performs an FEC redundant encoding
process of the supplied RTP packet to generate a
redundant packet. The FEC unit 132 supplies the
generated redundant packet to the RTP unit 133 with an
25 original RTP packet.
[0092]
The RTP unit 133 performs RTP-packetization of the
redundant packet supplied from the FEC unit 132. The
smoothing unit 134 smoothes a rate of the RTP packet
30 supplied from the RTP unit 133, and transmits it to the
network 102. An RTP time stamp for synchronization
specified by the media synchronization unit 136 is set in
each RTP packet in the RTP unit 164 (Fig. 3) or in the
RTP unit 133 (Fig. 2).
[0093]
5 In Fig. 1, the reception device 103 receives the
RTP packets transmitted from a plurality of the
transmission devices 101 once by the transmission unit
111 and allocates the RTP packet into the reception unit
113 corresponding to each transmission device 101. For
10 example, the.RTP packet transmitted from the transmission
device 101-K (K = 1,2,..,N) is allocated to the reception
unit 113-K.
[0094]
The reception unit 113 supplies the RTP packet to
15 the reception buffer 202 via the reception unit 201 (Fig.
7) and causes the reception unit 201 to hold it. At this
time, when a lost packet is detected, the fact of the
detection is notified to the ARQ unit 206. Upon
receiving the notification, the ARQ unit 206 performs a
20 retransmission request process.
[0095]
The reception buffer 202 determines a reception
buffer output time, which is a time at which the
reception buffer 202 outputs the RTP packet, and outputs
25 each RTP packet to the RTP unit 203 at that time, the
reception buffer output time being determined from the
reception buffer time determined by the reception buffer
time setting unit 208, the time information notified from
the media synchronization unit 210, and the RTP time
30 stamp value set in each RTP packet.
[0096]
The RTP unit 203 reconfigures the RTP packet, and
supplies obtained FEC redundant encoded data to the FEC
unit 204. When a lost packet, which is a packet lost in
data transmission, is detected, the FEC unit 204 recovers
5 lost packet data by a redundant-encoding decoding process.
The FEC unit 204 outputs a processed RTP packet to the
decoding unit 205. The decoding unit 205 extracts
encoded data from the RTP packet, and performs a decoding
process of the encoded data to generate video data of a
10 baseband. Decoded video data is supplied to the
synthesis unit 115 (Fig. 1).
[0097]
The synthesis unit 115 synthesizes video data
images from a plurality of the reception units 113, and
15 outputs it from the video output IF "video OUT" to a
picture display device such as a display, for example.
[0098]
[A reference signal synchronization process]
Next, a reference signal synchronization process
20 for synchronizing a reference signal will be described.
The reference signal synchronization unit 112 (Fig. 1)
synchronizes a reference signal clock between the
transmission device 101 and the reception device 103
using an IEEE 1588 precision time protocol (PTP). Note
25 that, as a frequency of the reference signal clock, a
pixel sampling frequency of an input video image may be
used, for example. In this case, synchronization with a
video output device input from "video IN" can also be
performed.
30 [0099]
Note that it may be configured such that the
reception device 103 is not provided with the reference
signal synchronization unit 112 and does not perform the
synchronization between the transmission device 101 and
the reception device 103.
5 [OlOO]
As shown in Fig. 1, in a case where a plurality of
the transmission devices 101 exists, the reception device
103 serves as a master and causes all of the transmission
devices 101 to synchronize with the reception device 103.
10 In this case, the reception device 103 synchronizes with
all of the transmission devices 101, whereby the
synchronization between all of the transmission devices
101 and the reception device 103 can be performed,
accordingly.
15 [OlOl]
[A media synchronization process]
The media synchronization unit 136 (Fig. 2) of the
transmission device 101 transforms a time synchronized
with a sampling time of data input from "video IN" into a
20 frequency of an RTP time stamp based on the time notified
from the reference signal synchronization unit 135, and
adds it to each RTP packet as an RTP time stamp in the
RTP unit 164 (Fig. 3) within the encoding unit 131 and
the RTP unit 133 (Fig. 2).
25 [0102]
The media synchronization unit 210 (Fig. 7) of the
reception device 103 holds the reference clock time
information notified from the reference signal
synchronization unit 112 (Fig. 1) as a system time
30 converted into an RTP time stamp frequency. The
reception buffer 202 (Fig. 7) of the reception device 103
determines a reception buffer output time of each RTP
packet when an RTP packet is recorded, the reception
buffer output time being determined from the RTP time
stamp value of the RTP packet, the reception buffer time
5 notified from the reception buffer time setting unit 208,
and the RTP time stamp frequency time supplied from the
media synchronization unit 210. The reception buffer 202
supplies the held RTP packet to the RTP unit 203 at the
reception buffer output time.
10 [0103]
The reception buffer output time of the RTP packet
is set as follows. For example, assume that a head
packet of encoded data is output from a reception buffer
at a time after a reception buffer time TSTIME- B UF
15 elapses from a received time, and a subsequent packet is
output in synchronization with a time calculated from a
differential value between an RTP time stamp value of the
head packet and an RTP time stamp value of the subsequent
packet.
20 [0104]
A reception buffer output time TSSYS- B O- n of an RTP
packet n is, for example, calculated with the following
formula (1). Here, the RTP time stamp value of the head
packet of encoded data is TSPKT- i nit, the reception time
25 (system time conversion: the frequency is an RTP time
stamp frequency) is TSSYS- i nit, and the RTP time stamp
value of the RTP packet n is TSPKT- n .
[0105]
TSSYS- B O- n = (TSPKT- n - SPKT- i nit) + TSSYS- i nit +
30 TSTIME- B UF (1)
[0106]
[A codec process]
The encoding unit 131 is, for example, a
hierarchical encoding system proposed in Patent Document
1, in which wavelet transformation is performed for each
5 several lines of each picture of a moving image as one
compression encoding block, and using an encoding system
having a different range of related input data for each
hierarchy.
[0107]
10 The encoding unit 131 (Fig. 2) of the transmission
device 101 performs an encoding process, and the decoding
unit 205 (Fig. 7) in the reception device 103 performs a
decoding process.
[0108]
15 The encoding unit 131 (Fig. 2) of the transmission
device 101 includes the rate control unit 141 as an
internal processing unit. The rate control unit 141
performs, for example, a rate control that controls an
encode rate not to overflow, where a bucket size is an
20 encoder assumed buffer size B (byte) and a bucket rate R
(bps) is an encode rate in a token bucket behavior
specified in ITU-T Y.1221. A buffer time required in the
reception device 103 when the rate is subjected to
smoothing-transmission is defined as a variable
25 compression encoding delay time.
[0109]
The variable compression encoding delay time
Bt - codec (sec) is, for example, expressed by the
following formula (2) .
30 [OllO]
Bt codec = B x 8/R 0 . - (2)
[Olll]
The encoder assumed buffer size B is determined in
accordance with the image quality request specified by
the user and the like. In a case of compression encoding
5 by VBR system, by having a large encoder assumed buffer
size B, a larger amount of data can be used for an image
portion with high complexity, whereby the image quality
can be improved. That is, when the image quality request
is high, by making the encoder assumed buffer size B
10 large, it can be responded to the high request.
[0112]
However, when the encoder assumed buffer size B is
made large, a variable compression encoding delay request
time Bt codec req (sec) becomes large, - - and therefore,
15 there is a concern of increasing a delay.
[0113]
[An RTCP process]
Next, an RTCP process of a QoS control process
performed between each transmission device 101 and the
20 reception device 103 will be described. The RTCP unit
137 (Fig. 2) and the RTCP unit 207 (Fig. 7) perform
transmission/reception of an RTCP message between the
transmission device 101 and the reception device 103
using RTCP specified in IETF RFC 3550, and perform
25 information collection such as a packet loss rate, a
reciprocating transmission delay (RTT), and a network
jitter, and the transmission/reception of a control
message for the QoS control process. The QoS control
message includes, for example, a retransmission request
30 message in an ARQ process, and the like.
[0114]
[An FEC process]
Next, an FEC process of the QoS control process
will be described. The FEC unit 132 (Fig. 2) performs
FEC redundant encoding of an RTP packet of encoded data
5 supplied from the encoding unit 131 as a unit. For
example, the FEC unit 132 performs redundant encoding
using an erasure error correction code such as a Reed-
Solomon code.
[ 0 11 5 ]
10 The redundancy in the FEC redundant encoding is,
for example, determined by the transmission quality
request specified by the user and the like. The
redundancy is specified in the form of (the number of
original data packets and the number of redundant
15 packets). The user also specifies an assumed packet loss
rate p of a network.
[0116]
Hereinafter, a pair of (the number of original data
packets and the number of redundant packets) is one
20 redundant code unit (so-called "FEC block"). For example,
when it is specified that (the number of original data
packets and the number of redundant packets) = (10,5),
the FEC unit 132 of the transmission device 101 generates
five redundant packets with respect to ten original data
25 packets. That is, a total of 15 packets are transmitted
in this FEC block.
[0117]
In this case, if the FEC unit 204 (Fig. 7) of the
reception device 103 receives any ten packets in the FEC
30 block packet, the original data can be decoded by an FEC
decoding process. For example, where the packet loss
rate specified by the user is p, the number of packets in
the FEC block is n, the number of original data packets
is k, the number of redundant packets is n-k, and a
target FEC block loss rate specified as the transmission
5 quality request by the user is Pt, the target FEC block
loss rate Pt is expressed by the following formula (3).
[ 0 11 8 ]
[Formula 11
n-k
The number of original data packets k and the
number of redundant packets n-k are determined so as to
satisfy the formula (3).
[0120]
15 In the reception device 103 (FEC unit 204 (Fig. 7))
in Fig. 1, it is necessary to set a reception buffer time
to be equal to or longer than the time from when a head
packet of the FEC block is arrived at the reception
device 103 till when a tailing packet is arrived (so-
20 called "redundant encoding block reception waiting time")
in order to recover a lost packet by the FEC redundant
decoding process.
[0121]
The redundant encoding block reception waiting time
25 corresponding to the FEC block set according to the
transmission quality request specified by the user and
the like is referred to as "redundant encoding block
reception waiting request time".
[0122]
30 [An ARQ process]
In an ARQ process in the reception device 103 of
Fig. 1, the reception unit 201 (Fig. 7) detects a lost
packet using a sequence number of the RTP packet, the ARQ
unit 206 generates a retransmission request message of
5 the lost packet, and the RTCP unit 207 transmits the
retransmission request message to the transmission device
101 to perform the retransmission request.
[0123]
Note that, when the ARQ unit 206 of the reception
10 device 103 performs the retransmission request of the
packet lost, and the reception unit 201 does not receive
a retransmission packet after a reciprocating
transmission time (ARQ retransmission packet waiting
time) elapses, the retransmission request may again be
15 performed. Further, until it is determined that arrival
of the retransmission packet misses the reception buffer
time of the packet, the ARQ unit 206 may repeat such a
retransmission request.
[0124]
20 In the ARQ process in the transmission device 101,
when the RTCP unit 137 (Fig. 2) receives the
retransmission request message, the ARQ unit 138
generates an RTP packet (retransmission packet) to be
retransmitted, supplies the retransmission packet to the
25 smoothing unit 134, and causes the smoothing unit 134 to
retransmit the retransmission packet.
[0125]
The recovery performance in the ARQ process depends
on an ARQ retransmission packet waiting time, which is a
30 time for waiting a retransmission packet by a request of
the ARQ unit 206 (Fig. 7) in the reception device 103.
The longer the ARQ retransmission packet waiting time is,
the further improved the recovery performance is.
However, it is necessary to have the reception buffer
time equal to or longer than the ARQ retransmission
5 packet waiting request time. Therefore, there is a
concern of increasing a delay.
[0126]
This "ARQ retransmission packet waiting request
time" is determined by the transmission quality request
10 specified by the user and the like.
[0127]
[A network jitter handling process]
The reception buffer 202 (Fig. 7) of the reception
device 103 is also provided with a network jitter
15 handling process mechanism. The reception buffer 202
sets a time equal to or longer than a "network jitter
handling buffer request time" determined by the
transmission quality request specified by the user and
the like as the reception buffer time. In this way, the
20 synchronization process of a packet subjected to a jitter
equal to or shorter than the "network jitter handling
buffer request time" becomes possible.
[0128]
[A whole data transmission system]
25 Next, an example of a whole flow of a data
transmission process executed in the transmission system
100 will be described with reference to a flowchart in
Fig. 9.
[0129]
30 Before starting data transmission, the RTCP unit
207 of each reception unit 113 communicates with the
transmission device 101 corresponding thereto, and
measures a network condition at step S121. Meanwhile,
the RTCP unit 137 of each transmission device 101
measures the network condition at step S101.
5 [0130]
That is, a condition in relation to communication
of the network 102 (network condition information) is
measured by transference/acceptance of a packet firstly
performed between the RTCP unit 137 and the RTCP unit 207.
10 [0131]
Before starting transmission of encoded data, the
RTCP unit 137 transmits dummy data used for network
condition preliminary measurement. The dummy data is
transmitted to the RTCP unit 207 via the network 102.
15 The RTCP unit 207 receives the dummy data, and performs
measurement (preliminary measurement) from information at
the time of transmission specified in the packet and a
condition at the time of reception.
101321
20 Upon obtaining network condition information, the
reception buffer time setting unit 208 performs a
reception buffer time determination process, performs
setting in the reception unit 113, and performs
notification in relation to the reception buffer time to
25 the transmission device 101 at step S122.
[0133]
The reception buffer time/processing parameter
setting unit 139 of the transmission device 101 performs
a reception buffer time/processing parameter setting
30 process, and sets various parameters upon receiving the
notification from the reception device 103 at step S102.
The transmission device 101 and the reception
device 103 perform a data transmission process in
cooperation with each other at respective steps S103 and
5 S123 in which an RTP packet of video data is transmitted
from the transmission device 101 to the reception device
103.
[0135]
[A reception buffer time determination process]
10 Next, an example of a flow of the reception buffer
time determination process executed at step S122 of Fig.
9 will be described with reference to Fig. 10.
[0136]
In the reception buffer time determination process,
15 adjustment of the reception buffer time is performed so
as to synchronize all of the reception units 113. The
synchronization here means that, when a packet including
data captured at the same time is input to all of the
reception units 113, the packet is output from the
20 reception buffer 202 at the same timing.
[0137]
To perform a synchronization output, as shown in
Fig. 11, it is necessary to perform adjustment
considering a difference between transmission delay times
25 (a difference in length between the transmission delays).
[ 0 13 8 1
The integrated reception buffer time adjustment
unit 114 obtains a maximum transmission delay time that
is the longest delay time from among transmission delays
30 of data transmission performed by the reception units 113
at step S141. This maximum transmission delay time is
obtained with the following formula (4).
[0139]
Maximum transmission delay time = MAX (a
transmission delay time 1, a transmission delay time 2,
5 --., and a transmission delay time N) 0 . - (4)
[0140]
Note that, in formula (4), MAX ( ) is a function for
calculating a maximum value.
[0141]
10 The integrated reception buffer time adjustment
unit 114 selects a reception unit to be processed from
among unprocessed reception units 113 to be used for the
data transmission at step ,5142.
[0142]
15 The reception buffer time setting unit 208 of the
selected reception unit 113 to be processed calculates
the reception buffer time using the maximum transmission
delay time, the transmission delay time of the data
transmission by this reception unit 113, and a prescribed
20 reception buffer time at step S143.
[0143]
The prescribed reception buffer time is a minimum
reception waiting time required in the encoding process
and the QoS control process, and is determined in advance.
25 The reception buffer time is a buffer time for
synchronization by absorbing a difference between the
transmission delays of the data transmission from the
transmission devices 101. The reception buffer time
includes the prescribed reception buffer time. That is,
30 the reception buffer time is obtained by adjusting the
prescribed reception buffer time (typically, by making
the prescribed reception buffer time longer) in
accordance with the length of the transmission delay of
each data transmission.
[ 0 14 4 ]
5 The reception buffer time can be calculated with
the following formula (5) .
[0145]
Reception buffer time K = Maximum transmission
delay time - Transmission delay time K + Prescribed
10 reception buffer time (5)
Note that K = 1, m e - , N
[0146]
For example, assume that a transmission device
process delay 251, which is a delay time by a process in
15 the transmission device 101, and a transmission delay 252,
which is a delay time by transmission via the network 102,
in data transmission of each transmission device 101, are
like the example shown in the upper drawing of Fig. 11.
[0147]
20 In this example, a transmission delay 252-1 of a
transmission device 101-1 is the longest. Therefore,
this transmission delay 252-1 serves as the maximum
transmission delay time.
[0148]
25 As shown in the lower drawing of Fig. 11, a
reception buffer time 254-1 of the data transmission of
the transmission device 101-1 has an equal length to a
prescribed reception buffer time 253. Meanwhile, a
difference in length of the transmission delays is added
30 to the prescribed reception buffer time 253 in the
reception buffer time 254 of the data transmission of
other transmission device 101.
[0149]
Therefore, the sum of the transmission device
processed delay, the transmission delay, and the
5 reception buffer time is common in each data transmission.
Therefore, the delay time in the whole data transmission
is not increased.
[0150]
As described above, by setting the reception buffer
10 time as longer as possible and adjusting the setting of a
parameter of the encoding process, the QoS control
process, and the like in accordance with the length of
the reception buffer time, the transmission device 101
and the reception device 103 are capable of performing
15 the parameter setting so as to improve the image quality
and the transmission quality without increasing the delay
time of the whole data transmission.
[0151]
Referring back to Fig. 10, when the reception
20 buffer time is calculated as described above, the
reception buffer time setting unit 208 sets various delay
times and waiting times such as a variable compression
encoding delay time, a redundant encoding block reception
waiting time, an ARQ retransmission packet waiting time,
25 and a network jitter handling buffer time from the
reception buffer time at step S144.
[0152]
Setting values in each process in a certain
transmission device 101-K (K = 1, ..., N) and a reception
30 unit 113-K corresponding thereto: a "variable compression
encoding delay time Kt', a "redundant encoding block
reception waiting time K", an "ARQ retransmission packet
waiting time K", and a "network jitter handling buffer
time K" are calculated from a 'reception buffer time K"
are calculated with the following formula (6).
5 [0153]
Variable compression encoding delay time K
= Redundant encoding block reception waiting time K
= ARQ retransmission packet waiting time K
= Network jitter handling buffer time K
10 = Reception buffer time K
(6) Note that K = 1, .-a, N
[0154]
As described above, when each time is set, the
reception buffer time setting unit 208 sets the " ARQ
15 retransmission packet waiting time" to the ARQ unit 206
at step S145, and allows the ARQ unit 206 to use it to
determine whether a retransmission request is performed.
[0155]
Also, the reception buffer time setting unit 208
20 sets the "network jitter handling buffer time" to the
reception buffer 202 at step S146.
[0156]
At step ,5147, the reception buffer time setting
unit 208 notifies the "variable compression encoding
25 delay time" and a "redundant encoding block waiting time"
to the transmission device 101 corresponding to the
reception unit 113 to be processed as an RTCP message via
the RTCP unit 207, for example.
[0157]
30 At step S148, the integrated reception buffer time
adjustment unit 114 determines whether all of the
reception units 113 have been processed. When it is
determined that an unprocessed reception unit 113 exists
among the reception units 113 to be used for data
transmission, the integrated reception buffer time
5 adjustment unit 114 returns the process to step S142,
selects a new reception unit to be processed, and repeats
the subsequent process for the new reception unit to be
processed.
[0158]
10 Also, at step S148, when it is determined that all
of the reception units 113 have been processed, the
reception buffer time determination process is terminated
and the process is returned to step S122 of Fig. 9, and
the subsequent process is performed.
15 [0159]
[A reception buffer time/processing parameter setting
process]
Next, the reception buffer time/processing
parameter setting process executed at step S102 of Fig. 9
20 will be described with reference to a flowchart of Fig.
12.
[0160]
When the reception buffer time/processing parameter
setting process is initiated, the reception buffer
25 time/processing parameter setting unit 139 acquires the
"variable compression encoding delay time" and the
"redundant encoding block waiting time" included in the
RTCP message supplied from the reception device 103 via
the RTCP unit 137 at step S161.
30 [0161]
At step S162, the reception buffer time/processing
parameter setting unit 139 sets the "variable compression
encoding delay time" to the encoding unit 131. At step
S163, the reception buffer time/processing parameter
setting unit 139 sets the "redundant encoding block
5 waiting time" to the FEC unit 132.
[0162]
The rate control unit 141 sets a rate control
parameter using the supplied "variable compression
encoding delay time" at step S164. For example, the rate
10 control unit 141 sets the encoder assumed buffer size B
(byte) so as to satisfy the following formula (7). Note
that, in the formula (7), "Bt codec (- sec)" represents the
variable compression encoding delay time. Also, "R
(bps)" represents a packet rate.
15 [0163]
Bt- c odec = B x 8/R .-- (7)
[0164]
The FEC unit 132 sets an FEC block parameter using
the "redundant encoding block reception waiting time" at
20 step S165. The "redundant encoding block waiting time"
is a maximum value of a time it takes to perform
smoothing-transmission of all of the packets included in
the FEC block. The FEC unit 132 adjusts the number of
original data packets of each FEC block such that this
25 time is equal to or shorter than the "redundant encoding
block waiting time". Further, the FEC unit 132 sets, for
example, the number of redundant packets n-k so as to
satisfy the above-described formula (3).
[0165]
30 When the process at step S165 ends, the reception
buffer time/processing parameter setting unit 139
terminates the reception buffer time/processing parameter
setting process, returns the process to step SlOl of Fig.
7, and performs the process at step S102.
[0166]
5 As described above, by performing various setting,
the transmission device 101 and the reception device 103
are capable of securing each delay time and waiting time
as long as possible to the extent not to increase a delay,
whereby the spare time can be used for the improvement of
10 the image quality and the transmission quality.
[0167]
To be more specific, the transmission device 101 is
capable of setting the "variable compression encoding
delay time" of the encoding unit 131 to the extent not to
15 increase a delay, and is capable of setting a larger
encoder assumed buffer size B (byte). Also, the
transmission device 101 is capable of setting the
"redundant encoding block waiting time" of the FEC unit
132 to the extent not to increase a delay, and is capable
20 of setting a larger FEC block and larger redundancy.
[0168]
The reception device 103 is capable of setting a
longer "ARQ retransmission packet waiting time" of the
ARQ unit 206 to the extent not to increase a delay. Also,
25 the reception device 103 is capable of setting a longer
"network jitter handling buffer time" of the reception
buffer 202 to the extent not to increase a delay.
[0169]
As described above, the transmission device 101 and
30 the reception device 103 are capable of reducing a waste
of a delay time by utilizing the spare time of each
process and using it for the improvement of the image
quality and the transmission quality. That is, the
transmission device 101 and the reception device 103 are
capable of suppressing deterioration of the content
5 quality by the above-described various processes in
relation to the data transmission.
[0170]
<2. Second embodiment>
[A configuration of a transmission system]
10 Note that, although it has been described that the
adjustment of the reception buffer time is performed only
according to the network condition, it is not limited to
the above description. For example, it may 'be configured
to cause a user and the like to input a request about the
15 image quality or the transmission quality and to adjust
the reception buffer time based on the input.
[0171]
Also, the reception buffer time may be renewed
during the data transmission.
20 LO1721
Fig. 13 is a block diagram showing a configuration
example of the transmission system of that case.
[0173]
Although a transmission system 300 shown in Fig. 13
25 has basically a similar system to the transmission system
100 of Fig. 1, the transmission system 300 includes a
reception device 303 instead of the reception device 103.
The reception device 303 is basically a similar device to
the reception device 103, but includes an input unit 311
30 and an output unit 312 in addition to a configuration of
the reception device 103.
LO1741
The input unit 311 is configured from an arbitrary
input device such as a keyboard, a mouse, a touch panel,
and a switch, an external input terminal, and the like,
5 receives an image quality request and a transmission
quality request from outside of the reception device 303
such as a user, and supplies it to an integrated
reception buffer time adjustment unit 114.
[0175]
10 The output unit 312 is configured from an arbitrary
output device such as a monitor and a speaker, an
external output terminal, and the like, and displays a
GUI image supplied from the integrated reception buffer
time adjustment unit 114 and outputs a sound to output an
15 input announcement and an input result of the image
quality request and the transmission quality request.
LO1761
Fig. 14 is a diagram showing a display example of a
request reception screen, which is a GUI receiving the
20 image quality request, the transmission quality request,
and the like. As shown in Fig. 14, a request reception
screen 321 includes a display unit 322 and a request unit
323. An item that can be input by the user is shown on
the request unit 323. A result of information input by
25 the user is shown on the display unit 322.
[0177]
It is shown that, in the request unit 323, for
example, an "image quality request" and a "transmission
quality request" can be input as a "user request". For
30 example, in a case where the image quality is specified,
the user selects the "image quality request" and inputs
quality to be requested (for example, a PSR value and the
like). Also, for example, in a case where the
transmission quality is specified, the user selects the
"transmission quality request" and inputs quality to be
5 requested (for example, a packet loss rate after QoS
control, and the like) .
[0178]
Note that the user can specify a reception buffer
time on the request unit 323. For example, the user
10 selects a "reception buffer time" and inputs a time to
request, so that an allowable longest time as the
"reception buffer time" can be set.
[0179]
Various types of information that reflect the
15 information input to the request unit 323 are displayed
on the display unit 322.
[0180]
For example, a "transmission delay" as a "network
condition" is displayed on the display unit 322 for each
20 transmission device. Obviously, information other than
the above may be displayed.
[0181]
Also, for example, as a "process request time", a
"variable compression encoding delay request time", a
25 "redundant encoding block reception request waiting time",
an "ARQ retransmission packet waiting request time", and
a "network jitter handling buffer request time", and the
like are displayed on the display unit 322.
[0182]
30 Further, for example, a "recommended reception
buffer time" recommended as the reception buffer time is
displayed on the display unit 322 for each transmission
device.
[ 0 18 3 ]
The user can more easily set the image quality
5 request, the transmission quality request, the reception
buffer time, and the like by inputting a request based on
such a GUI.
[0184]
[A whole data transmission process]
10 An example of a flow of a data transmission process
of the above case will be described with reference to a
flowchart of Fig. 15.
[0185]
In this case, as shown in Fig. 15, the reception
15 device 303 firstly controls the input unit 311 and the
output unit 312 to receive the image quality request and
the transmission quality request at step S321. The image
quality request is a request for the image quality of a
decoded image (an image of video data output from the
20 reception device 303). The transmission quality request
is a request for the packet loss rate and the like of a
network 102. The reception device 303 uses the received
image quality request and the transmission quality
request for setting various parameters.
25 101861
Subsequent processes are similar to the case
described with reference to the flowchart of Fig. 9.
That is, each process from steps S301 to S303 of Fig. 15
corresponds to each process from steps SlOl to S103 of
30 Fig. 9, and each process from steps S322 to S324 of Fig.
15 corresponds to each process from steps S121 to S123 of
Fig. 9.
[0187]
Note that, at step S323 of Fig. 15, a reception
buffer time determination process is performed using a
5 request received at step S321. Also, at steps S303 and
S324 of Fig. 15, a reception buffer dynamic change
transmission process is performed in which the reception
buffer time is renewed while the data transmission is
performed.
10 [0188]
[A reception buffer time determination process]
Next, an example of a flow of a reception buffer
time determination process executed in step ,5323 of Fig.
15 will be described with reference to flowcharts of Figs.
15 16 and 17.
[0189]
In this case, basically, each process is also
performed in a similar manner to the case described with
reference to the flowchart of Fig. 10. Note that, in
20 this case, the integrated reception buffer time
adjustment unit 114 obtains a provisional reception
buffer time (provisional reception buffer time) of each
reception unit 113 instead of using the prescribed
reception buffer time before obtaining a maximum
25 transmission delay time.
[0190]
That is, the integrated reception buffer time
adjustment unit 114 selects a reception unit 113 to be
processed at step S341 and calculates the "variable
30 compression encoding delay request time", the "redundant
encoding block reception waiting request time", the "ARQ
retransmission packet waiting request time", and the
"network jitter handling buffer request time" using the
image quality request and the transmission quality
request with respect to data transmission of the
5 reception unit 113 to be processed at step S342.
[0191]
At step S343, the integrated reception buffer time
adjustment unit 114 sets a maximum value of the
calculated "variable compression encoding delay request
10 time", "redundant encoding block reception waiting
request time", "ARQ retransmission packet waiting request
time", and "network jitter handling buffer request time"
as the provisional reception buffer time.
[0192]
15 The integrated reception buffer time adjustment
unit 114 determines whether all of the reception units
113 to be used for the data transmission have been
processed at step S344, and repeats the processes from
steps 5341 to S344 until all of the reception units 113
20 are processed.
[0193]
When the provisional reception buffer times of all
of the reception units 113 have been set, the integrated
reception buffer time adjustment unit 114 proceeds with
25 the process to step S345 and obtains a maximum
transmission delay time in a similar manner to the case
of step S141 of Fig. 10.
[0194]
That is, in this case, the reception buffer times
30 of the reception units 113 calculated without considering
the transmission delays are not a common prescribed
reception buffer time and are individually set
provisional reception buffer times, and there is a
possibility that the lengths thereof are different from
each other.
5 [0195]
However, in this case, a calculation method of the
reception buffer time is basically similar to the case of
Fig. 10, and each process of steps S351 to S357 of Fig.
17 is performed in a similar manner to each process of
10 steps S142 to S148 of Fig. 10 except that a maximum value
(maximum transmission delay time) of the provisional
reception buffer time is applied instead of the
prescribed reception buffer time.
[0196]
15 Further, a reception buffer time/processing
parameter setting process by each transmission device 101
is performed in a similar manner to the case described
with reference to the flowchart of Fig. 12.
[0197]
20 As described above, when the image quality request
and the transmission quality request are received from
the user and the reception buffer time is determined
according to the request, similar to the first embodiment,
a spare time of each process is efficiently used for the
25 improvement of the image quality and the transmission
quality, whereby a waste of a delay time can be reduced.
That is, deterioration of content quality can be
suppressed.
[0198]
30 [A reception buffer dynamic change transmission process]
Next, an example of a flow of the reception buffer
dynamic change transmission process performed by the
transmission device 101 and the reception device 303 will
be described with reference to a flowchart of Fig. 18.
[0199]
5 At step S371, each part of the transmission device
101 performs data transmission in a given time. In
response to this process, each part of the reception
device 303 performs data transmission in a given time at
step S391.
10 [0200]
An RTCP unit 207 of the reception device 303
performs data transmission/reception with an RTCP unit
137, measures a network condition, and renews network
condition information at step S392. In response to this
15 process, the RTCP unit 137 of the transmission device 101
measures the network condition and renews the network
condition information at step S372.
[0201]
At step S393, a reception buffer time setting unit
20 208 of the reception device 303 performs the reception
buffer time determination process based on the renewed
network condition information and renews the "variable
compression encoding delay request time", the "redundant
encoding block reception waiting request time", the "ARQ
25 retransmission packet waiting request time", the "network
jitter handling buffer request time" and the like. The
setting of the "variable compression encoding delay time",
the "redundant encoding block reception waiting time",
the 'ARQ retransmission packet waiting time", the
30 "network jitter handling buffer time", and the like are
renewed in accordance with the renewed various request
times using the formulas (4) and (5) .
This reception buffer time determination process is
performed in a similar manner to the case of Figs. 16 and
In response to this process, a reception buffer
time/processing parameter setting unit 139 of the
transmission device 101 performs the reception buffer
10 time/processing parameter setting process at step S373.
This process is performed in a similar manner to the case
of Fig. 12.
[0204]
In a case after the start of encoded data
15 transmission, the reception buffer time/processing
parameter setting unit 139 determines the number of
original data packets k and the number of redundant
packets n-k using a packet loss rate p included in the
network condition information measured by the RTCP unit
20 137 using the encoded data transmission so as to satisfy
the formula (3) .
[0205]
At step S374, the transmission device 101
determines whether the transmission is terminated, and
25 when it is determined that the transmission is terminated,
the transmission device 101 returns the process to step
S371 and causes the subsequent processes to be executed.
Also, at step S374, when it is determined that the
transmission is terminated, the reception buffer dynamic
30 change transmission process by the transmission device
101 is terminated.
[0206]
Also, at step S394, the reception device 303
determines whether the transmission is terminated, and
when it is determined that the transmission is terminated,
5 the reception device 303 returns the process to step S391
and causes the subsequent processes to be executed. Also,
at step S394, when it is determined that the transmission
is terminated, the reception buffer dynamic change
transmission process by the reception device 303 is
10 terminated.
[0207]
As described above, the transmission device 101 and
the reception device 303 are capable of efficiently
setting the image quality and the transmission quality in
15 accordance with an actual condition, whereby the waste of
the delay time can be further reduced by setting the
parameters and the like in accordance with not only the
requests from the user and the like but also the network
condition. That is, the transmission device 101 and the
20 reception device 303 are capable of suppressing the
deterioration of the content quality.
[0208]
As described above, in a case where a moving image
is transmitted from a plurality of transmission devices,
25 a synchronization process is performed in a reception
device, and a QoS control process such as a variable
compression encoding process, an FEC is performed, a
larger variable compression encoding request time,
redundant encoding block reception waiting time, ARQ
30 retransmission packet waiting time, and network jitter
handling buffer time can be set with respect to the data
transmission with a small transmission delay, whereby the
picture quality and the transmission quality can be
improved at a maximum.
[0209]
5 Note that, although it has been described such that
the video data to be transmitted is encoded, it is not
limited to the above embodiment and uncompressed data as
is may be transmitted.
[0210]
10 <3. Third embodiment >
[A personal computer]
The above-described series of processes may be
executed by hardware and may also be executed by software.
In this case, for example, it may be configured as a
15 personal computer shown in Fig. 19.
[0211]
In Fig. 19, a central processing unit (CPU) 401 of
a personal computer 400 executes various processes
according to a program stored in a read only memory (ROM)
20 402 or' a program loaded from a storage unit 413 to a
random access memory (RAM) 403. Data and the like
necessary for various processes executed by the CPU 401
are also properly stored in the RAM 403.
[0212]
25 The CPU 401, the ROM 402, and the RAM 403 are
mutually connected via a bus 404. An input/output
interface 410 is also connected to the bus 404.
[0213]
An input unit 411 configured from a keyboard, a
30 mouse, and the like, a display configured from a cathode
ray tube (CRT), a liquid crystal display (LCD), and the
like, an output unit 412 configured from a speaker and
the like, a storage unit 413 configured from hard disk
and the like, and a communication unit 414 configured
from a modem and the like are connected to the
5 input/output interface 410. The communication unit 414
performs a communication process via a network including
the internet.
[0214]
A drive 4'15 is also connected to the input/output
10 interface 410 as needed, a removable medium 421 such as a
magnetic disk, an optical disk, a magneto optical disk,
and a semiconductor memory is properly mounted, and a
computer program read out therefrom is installed into the
storage unit 413, as needed.
15 [0215]
When the above-described series of processes are
executed by software, a program that constitutes the
software is installed from the network or a recording
medium.
20 102161
This recording medium is, as shown in Fig. 19,
other than the main device, configured not only from the
removable medium 421 such as a magnetic disk (including a
flexible disk), an optical disk (including a compact
25 disc-read only memory (CD-ROM) and a digital versatile
disc (DVD)), a magneto optical disk (including a mini
disc (MD)), and a semiconductor memory, on which the
program is recorded and which is distributed for
delivering the program to the user, but also from the ROM
30 402 on which the program is recorded, or the hard disk
included in the storage unit 413, which is incorporated
in the main device in advance and delivered to the user.
[0217]
Note that the program executed by the computer may
be a program time-sequentially performed along the order
5 described in the present specification, or may be a
program executed in parallel or executed at a necessary
timing such as upon calling.
[0218]
Also, in the present specification, the steps
10 describing the program recorded in the recording medium
include not only the process time-sequentially performed
along the described order, but also a process executed
individually or in parallel even if it is not necessarily
time-sequentially performed.
15 [0219]
Also, in the present specification, the 'system"
represents a whole apparatus configured from a plurality
of devices (apparatuses).
[0220]
20 Also, the configuration that has been described in
the above embodiments as one device (or a processing
unit) may be divided and configured from a plurality of
devices (or processing units). On the contrary, the
configuration that has been described in the above
25 embodiments as a plurality of devices (or processing
units) may be configured from an integrated one device
(or a processing unit). Further, a configuration other
than the above-described configuration of each device (or
each processing unit) may be obviously added. Further, a
30 part of the configuration of a certain device (or a
processing unit) may be included in a configuration of
other device (or other processing unit) as long as the
configuration or the operation as the whole system is
substantially the same. That is, the embodiment of the
present invention is not limited to the above-described
5 embodiments and various modifications may be made without
departing from the scope of the present invention.
REFERENCE SIGNS LIST
[0221]
10 100 Transmission system
101 Transmission device
102 Network
103 Reception device
111 Transmission unit
15 112 Reference signal synchronization unit
113 Reception unit
114 Integrated reception buffer time adjustment unit
115 Synthesis unit
131 Encoding unit
20 132 FECunit
133 RTP unit
134 Smoothing unit
135 Reference signal synchronization unit
136 Media synchronization unit
25 137 RTCPunit
138 ARQunit
139 Reception buffer time/processing parameter setting
unit
141 Rate control unit
30 201 Reception unit
202 Reception buffer
RTP unit
FEC unit
Decoding unit
ARQ unit
RTCP unit
Reception buffer time setting unit
Media synchronization unit
Transmission system
Reception device
Input unit
Output unit

CLAIMS
1. An information processing apparatus, comprising:
an adjustment means configured to adjust, in data
5 transmission for transmitting mutually synchronized data
from a plurality of transmission devices to a reception
device, a reception buffer time that is a buffer time for
synchronizing each of the data in the reception device
and is set for each of the data transmission using a
10 difference in transmission delays that are a delay time
generated in a transmission line of each of the data
transmission; and
a setting means configured to set a parameter of a
process in relation to each of the data transmission
15 using the reception buffer time adjusted by the
adjustment means.
2. The information processing apparatus according to
claim 1,
20 wherein the adjustment means obtains a maximum
value of the transmission delays, and obtains the
reception buffer time by adding a difference between the
transmission delay of each of the data and the maximum
value to a prescribed reception buffer time that is a
25 predetermined reception buffer time.
3. The information processing apparatus according to
claim 1,
wherein the process in relation to the data
30 transmission is a QoS control process of the data
transmission, and
the setting means sets, as the parameter of the QoS
control process, a redundant encoding block reception
waiting time that is a time from when a head packet of a
redundant encoding block is received until a tailing
5 packet of the redundant encoding block is received, a
retransmission packet waiting time that is a time for
waiting a retransmission packet, and a network jitter
handling buffer time for absorbing a network jitter.
10 4. The information processing apparatus according to
claim 1,
wherein the data is encoded in a transmission
source, obtained encoded data is transmitted, and the
encoded data is decoded in a transmission destination,
15 and
the setting means sets, as the parameter of the
process, a variable compression encoding delay request
time necessary when the encoded data rate-controlled and
generated at the encoding is subjected to smoothing-
20 transmission.
5. The information processing apparatus according to
claim 1, further comprising:
a reception means configured to receive an image
25 quality request that is a request in relation to image
quality of the data and a transmission quality request
that is a request in relation to transmission quality in
the data transmission,
wherein the adjustment means adjusts the reception
30 buffer time based on the image quality request and the
transmission quality request received by the reception
means.
6. The information processing apparatus according to
claim 5,
5 wherein the adjustment means sets a provisional
reception buffer time based on the image quality request
and the transmission quality request received by the
reception means, and adjusts the reception buffer time
based on the provisional reception buffer time.
10
7. The information processing apparatus according to
claim 5, further comprising:
an output means configured to display a GUI
supporting an input of the image quality request and the
15 transmission quality request received by the reception
means.
8. An information processing method to be performed by
an information processing apparatus, comprising:
20 in data transmission for transmitting mutually
synchronized data from a plurality of transmission
devices to a reception device, adjusting, by an
adjustment means of the information processing apparatus,
a reception buffer time that is a buffer time for
25 synchronizing each of the data in the reception device
and is set for each of the data transmission using a
difference in transmission delays that are a delay time
generated in a transmission line of each of the data
transmission; and
30 setting, by a setting means of the information
processing apparatus, a parameter of a process in
relation to each of the data transmission using the
adjusted reception buffer time.
9. A program for causing a computer, which performs
5 data transmission, to function as:
an adjustment means that adjusts, in data
transmission for transmitting mutually synchronized data
from a plurality of transmission devices to a reception
device, a reception buffer time that is a buffer time for
10 synchronizing each of the data in the reception device
and is set for each of the data transmission using a
difference in transmission delays that are a delay time
generated in a transmission line of each of the data
transmission; and
15 a setting means that sets a parameter of a process
in relation to each of the data transmission using the
reception buffer time adjusted by the adjustment means.