DESCRIPTION
DISPLAY CONTROL APPARATUS, DISPLAY CONTROL METHOD, AND
PROGRAM
5 TECHNICAL FIELD
[ OOOl]
The present disclosure relates to a display control
apparatus, a display control method and a program and,
more particularly, relates to a display control apparatus,
10 a display control method and a program which can suppress,
for example, distortion of an image caused when, for
example, an image transmitted from a data transmission
channel such as a network is displayed with a little
delay.
BACKGROUND ART
[0002]
In recent years, for example, telesurgeries of
performing operations of patients by operating robot arms
20 at a remote place are performed. Upon this telesurgery,
a surgeon operates the robot arms looking at movies
obtained by capturing images of the operation, and the
movies are desirably transmitted with a little delay (in
substantially real time) equal to or less than several
25 frames (or several fields) .
Hence, a coding technique of transforming several
lines of each picture configuring a movie into block data
and coding (compressing) each block data by wavelet
30 transform has been proposed (see, for example, Patent
Document 1) .
According to this coding technique, a transmission
apparatus starts coding without waiting to receive all
inputs of each block data in a picture and transmits
5 resulting coded data, and a reception apparatus starts
decoding (stretching) before receiving all items of the
coded data from the transmission apparatus.
[0005]
Hence, the reception apparatus can decode the coded
10 data and place the picture in a displayable state by a
predetermined display timing at which the picture needs
to be displayed. Consequently, the reception apparatus
can display the picture on a monitor in synchronization
with the display timing.
15
CITATION LIST
PATENT DOCUMENT
[0006]
Patent Document 1: Japanese Patent Application Laid-Open
20 No. 2007-311924
SUMMARY OF THE INVENTION
PROBLEMS TO BE SOLVED BY THE INVENTION
[0007]
25 However, even when the above coding technique is
applied, if, for example, congestion occurs in a data
transmission channel such as a network, the transmission
apparatus is likely to be incapable of transmitting
movies with a little delay equal to or less than several
30 frames.
[0008]
In this case, the reception apparatus cannot place
a picture in a displayable state by the predetermined'
display timing. The picture which is not placed in a
displayable state by the display timing is, for example,
5 skipped without being displayed on the monitor, and,
therefore, for example, distortion of the image to be
displayed on the monitor is likely to occur.
[0009]
The present disclosure'has been made in light of
10 the above circumstances, and is directed to suppress, for
example, distortion of an image caused when an image
transmitted from a data transmission channel is displayed
with a little delay.
15 SOLUTION TO PROBLEMS
[OOlO]
A display control apparatus according to an aspect
of the present disclosure includes: a measurement unit
which measures a write preparation time required to start
20 writing a received image in a hold unit which temporarily
holds the image; a write control unit which controls the
writing of the image according to whether or not the
write preparation time is a threshold time or more which
represents a write preparation time at which the writing
25 of the image is finished at a display end time at which
the image is displayed in synchronization with a display
timing at which the image needs to be displayed; and a
display control unit which displays the image written in
the hold unit under control of the write control unit in
30 synchronization with the display timing by a write time
at which the image is displayable in synchronization with
the display timing.
[OOll]
When the write preparation time is the threshold
time or more, the write control unit can start the
5 writing of the image after the display timing passes by
delaying the writing of the image started when the write
preparation time passes.
[0012]
A calculation unit which calculates a maximum value
10 of a buffer capacity used to delay the writing of the
image in the write control unit can be further provided.
[0013]
When writing of a first image which needs to be
displayed at a first display timing is started after the
15 first display timing passes, the display control unit can
display a second image which has been written in the hold
unit under control of the write control unit and which is
different from the first image, in synchronization with
the first display timing.
20 [0014]
When the writing of the first image is started
after the first display timing passes, the display
control unit can display the second image, writing of
which is started after a second display timing which
25 comes earlier than the first display timing passes, in
synchronization with the first display timing.
[0015]
When the write preparation time is less than the
threshold time, the write control unit can start writing
30 the image after the write preparation time passes.
[0016]
When the writing of the first image which needs to
be displayed at a first display timing is started after
the writing preparation time passes, the display control
unit can finish writing part of the first image by a
5 write time at which the first image is displayable in
synchronization with the first display timing, and, when
writing of the rest of the first image is not finished,
can display the part of the first image written in the
hold unit, in synchronization with the first display
10 timing.
[0017]
When writing of a second image which needs to be
displayed at a second display timing which comes after
the first display timing is started after the second
15 display timing passes, the display control unit displays
the part of the first image and, in addition, the first
image the rest of which has been written, in
synchronization with the second display timing.
20 Another measurement unit which measures a write
time required to write an image; and a threshold
calculation unit which calculates the threshold time
based on a distribution of the write preparation time and
a distribution of the write time can be further provided,
25 and the write control unit controls the writing of the
image according to whether or not the write preparation
time is the calculated threshold time or more.
[0019]
A display control method according to an aspect of
30 the present disclosure is performed by a display control
apparatus which displays a received image, and the method
includes: a measurement step of measuring a write
preparation time required to start writing a received
image in a hold unit which temporarily holds the image; a
write control step of controlling the writing of the
5 image according to whether or not the write preparation
time is a threshold time or more which represents a write
preparation time at which the writing of the image is
finished at a display end time at which the image is
displayed in synchronization with a display timing at
10 which the image needs to be displayed; and a display
control step of displaying the image written in the hold
unit under control of the write control unit in
synchronization with the display timing by a write time
at which the image is displayable in synchronization with
15 the display timing.
[0020]
A program according to an aspect of the present
disclosure causes a computer to function as: a
measurement unit which measures a write preparation time
20 required to start writing a received image in a hold unit
which temporarily holds the image; a write control unit
which controls the writing of the image according to
whether or not the write preparation time is a threshold
time or more which represents a write preparation time at
25 which the writing of the image is finished at a display
end time at which the image is displayed in
synchronization with a display timing at which the image
needs to be displayed; and a display control unit which
displays the image written in the hold unit under control
30 of the write control unit in synchronization with the
display timing by a write time at which the image is
displayable in synchronization with the display timing.
[0021]
According to an aspect of the present disclosure, a
write preparation time required to start writing a
5 received image in a hold unit which temporarily holds the
image is measured, the writing of the image is controlled
according to whether or not the write preparation time is
a threshold time or more which represents a write
preparation time at which the writing of the image is
10 finished at a display end time at which the image is
displayed in synchronization with a display timing at
which the image needs to be displayed, and the image
written in the hold unit under control of the write
control unit is displayed in synchronization with the
15 display timing by a write time at which the image can be
displayed in synchronization with the display timing.
EFFECTS OF THE INVENTION
[0022]
20 The present disclosure can suppress, for example,
distortion of an image caused when an image transmitted
from a data transmission channel is displayed with a
little delay.
25 BRIEF DESCRIPTION OF DRAWINGS
[0023]
Fig. 1 is a block diagram illustrating a
configuration example of a transmission/reception system
according to the present disclosure.
30 Fig. 2 is a view illustrating an example where an
image is displayed in synchronization with a display
timing.
Fig. 3 is a view illustrating an example of a
measurement method of measuring write information of a
field image.
5 Fig. 4 is a view illustrating an example of a
distribution of write preparation times.
Fig. 5 is a view illustrating an example of a
distribution of buffer write times.
Fig. 6 is a first view illustrating an example of a
10 calculation method of calculating a threshold to be
compared with the write preparation time and a delay
buffer maximum time.
Fig. 7 is a second view illustrating an example of
the calculation method of calculating the threshold to be
15 compared with the write preparation time and the delay
buffer maximum time.
Fig. 8 is a view illustrating an example where
start of writing is delayed.
Fig. 9 is a view illustrating an example of a delay
20 buffer maximum time.
Fig. 10 is a view illustrating an example where a
field image written by delaying start of writing is
displayed.
Fig. 11 is a view illustrating an example where
25 writing is started after a write preparation time passes.
Fig. 12 is a view illustrating an example where a
write time comes at or after a display time when writing
is started after a write preparation time passes.
Fig. 13 is a view illustrating an example where
30 whether or not a write time comes at or after a display
time is monitored when writing is started after a write
preparation time passes.
Fig. 14 is a first view illustrating an example
where a transmission time changes.
Fig. 15 is a second view illustrating an example
5 where a transmission time changes.
Fig. 16 is a flowchart for explaining display
control processing.
Fig. 17 is a flowchart for explaining threshold
calculation processing.
10 Fig. 18 is a view illustrating an example of a
measurement method of measuring write information of a
progressive image.
Fig. 19 is a block diagram illustrating a
configuration example of a computer.
MODE FOR CARRYING OUT THE INVENTION
[0024]
Hereinafter, an embodiment according to the present
disclosure (referred to as "the present embodiment"
20 below) will be described. In addition, the present
embodiment will be described in the following order.
1. Present Embodiment (an example where, for example,
distortion of an image is suppressed by adjusting a write
timing of an image in a display buffer)
25 2. Modified Example
[0025]
<1. Present Embodiment>
[Configuration Example of Transmission/Reception System]
Fig. 1 illustrates an example of a
30 transmission/reception system according to the present
disclosure.
This transmission/reception system includes a
transmission apparatus 21, a reception apparatus 22 and a
network 23 such as Internet.
5 [0027]
In addition, for example, in this
transmission/reception system, the reception apparatus 22
adjusts a timing to write an image in a display buffer 65
which will be described below to display the image with a
10 little delay without causing, for example, distortion of
the image transmitted from the transmission apparatus 21.
[0028]
[Configuration Example of Transmission Apparatus 211
The transmission apparatus 21 includes a capture
15 unit 41, a coding unit 42, a packet configuration unit 43,
an RTP (real-time transport protocol) transmission unit
44, an operation unit 45 and a control unit 46.
[0029]
The capture unit 41 acquires (captures) image data
20 (corresponding to video IN) input from an outside, and
supplies the image data to the coding unit 42.
[0030]
The coding unit 42 performs coding processing of
coding the image data from the capture unit 41, and
25 supplies the coded data resulting from the coding
processing, to the packet configuration unit 43.
[0031]
In addition, for the coding processing, it is
possible to adopt wavelet coding processing of coding
30 image data using, for example, wavelet transform and
compressing the image data.
[0032]
The packet configuration unit 43 packetizes
(transforms) the coded data from the coding unit 42 to a
plurality of RTP packets, and outputs the RTP packets to
5 the RTP transmission unit 44. In addition, the RTP
packet refers to a packet in a format supporting RTP
disclosed in IETF RFC3550.
[0033]
The RTP transmission unit 44 adds, for example,
10 transmission times at which the RTP packets are
transmitted to the reception apparatus 22, to the RTP
packets from the packet configuration unit 43 as time
stamps according to RTP. Further, the RTP transmission
unit 44 transmits the RTP packets to which the time
15 stamps are added, to the reception apparatus 22 through
the network 23.
[0034]
The operation unit 45 is, for example, an operation
button operated by a user, and supplies an operation
20 signal matching a user operation to the control unit 46.
[0035]
The control unit 46 controls each of the capture
unit 41, the coding unit 42, the packet configuration
unit 43 and the RTP transmission unit 44 based on, for
25 example, an operation signal from the operation unit 45.
[0036]
[Configuration Example of Reception Apparatus 221
The reception apparatus 22 includes an RTP
reception unit 61, a packet assemble unit 62, a decoding
30 unit 63, a write control unit 64 with a built-in delay
buffer 64a, a display buffer 65, a display control unit
66, a display unit 67, a write information measurement
unit 68, a write information storage unit 69, a threshold
calculation unit 70, an operation unit 71 and a control
unit 72.
5 [0037]
The RTP reception unit 61 receives the RTP packets
transmitted from the RTP transmission unit 44 through the
network 23, and supplies the RTP packets to the packet
assemble unit 62.
10 [0038]
The packet assemble unit 62 generates decoding
target coded data by assembling the RTP packets from the
RTP reception unit 61, and supplies the coded data to the
decoding unit 63.
15 [0039]
The decoding unit 63 applies decoding processing
supporting the coding processing performed in the coding
unit 42, to the coded data from the packet assemble unit
62, and supplies the resulting image data to the write
20 control unit 64. Meanwhile, for decoding processing,
decoding processing of decoding and stretching data by,
for example, inverse transform of wavelet transform is
adopted.
[0040]
25 The write control unit 64 supplies the image data
from the decoding unit 63 to the display buffer 65 to
store (write in). That is, the write control unit 64
controls writing of image data in the display buffer 65
according to information from the write information
30 measurement unit 68. Further, the write control unit 64
supplies a write start time Ts at which writing in the
display buffer 65 is started and a write end time Te at
which writing is finished, to the write information
measurement unit 68 per image data.
[0041]
5 The display buffer 65 temporarily holds the image
data from the write control unit 64.
[0042]
The display control unit 66 reads the image data
from the display buffer 65. Further, the display control
10 unit 66 causes the display unit 67 to display the image
data read from the display buffer 65 in synchronization
with a predetermined display timing Vblank.
[0043]
Next, Fig. 2 illustrates an example where the
15 display control unit 66 causes each image to be displayed
at the predetermined display timing Vblank.
[0044]
In addition, image data n is image data which is
captured n-th by the capture unit 41 of the transmission
20 apparatus 21. The image data n is configured by an oddnumbered
field image nodd configured by odd-numbered lines
of each line configuring the image data n, and an evennumbered
field image neven configured by the even-numbered
lines of each line configuring the image data n.
25 [0045]
Further, in Fig. 2, a horizontal axis indicates the
time, and a vertical axis indicates a line number of a
line to be displayed at a corresponding time. Meanwhile,
the image data n is configured by, for example, 1080
30 lines, and the odd-numbered field image nodd and the evennumbered
field image neVen are each configured by 540
lines.
[0046]
The display timing Vblank (nodd) indicates the time
at which display of the odd-numbered field image nodd is
5 started. Further, the display timing Vblank (n,,,,)
indicates the time at which display of the even-numbered
field image n,,,, is started.
[0047]
The display control unit 66 reads the odd-numbered
10 field image nodd from the display buffer 65 in
synchronization with the display timing Vblank (nodd), and
causes the display unit 67 to display the odd-numbered
field image nodd. Further, the display control unit 66
reads the even-numbered field image n,,,, from the display
15 buffer 65 in synchronization with the display timing
Vblank (n,,,,), and causes the display unit 67 to display
the even-numbered field image n,,,, .
[0048]
The display unit 67 displays each image data n
20 according to, for example, an interlace system. That is,
for example, the display unit 67 alternately displays the
odd-numbered field image n,dd and the even-numbered field
image n,,,, under control of the display control unit 66.
In addition, the display unit 67 may be a component of
25 the reception apparatus 22 as illustrated in Fig. 1, or
may be independently provided without being included as
the component of the reception apparatus 22. In this
case, the display control unit 66 in the reception
apparatus 22 and the display unit 67 provided outside the
30 reception apparatus 22 are connected through, for example,
a cable.
[0049]
The write information measurement unit 68 measures
write information of the even-numbered field image neven
written in the display buffer 65. In addition, the write
5 information measurement unit 68 may measure write
information of the odd-numbered field image nodd written
in the display buffer 65 instead of the write information
of the even-numbered field image neven or together with
the write information of the even-numbered field image
10 neven
[0050]
Further, when, for example, the display unit 67
displays each image data n according to the progressive
system, the write information measurement unit 68 regards
15 each image data n as a progressive image and measures
write information of this progressive image. This will
be described below with reference to Fig. 18.
[0051]
Hereinafter, the write information measurement unit
20 68 measures write information of each field image (the
odd-numbered field image nodd and the even-numbered field
image neven) written in the display buffer 65.
[0052]
As write information of the even-numbered field
25 image neven written in the display buffer 65, the write
information measurement unit 68 measures, for example, a
write preparation time Xneve, required by a time at which
writing of the even-numbered field image neven is started
and a buffer write time Pneven required to write the even-
30 numbered field image neven.
[0053]
Next, Fig. 3 illustrates an example where the write
information measurement unit 68 measures the write
preparation time XneVen and the buffer write time Pneve, of
the even-numbered field image neVe.n
5 [0054]
Meanwhile, in Fig. 3, the write start time Ts
indicates a time at which writing of the even-numbered
field image neven in the display buffer 65 is started.
Further, the write end time Te indicates a time at which
10 writing of the even-numbered field image neven in the
display buffer 65 is finished.
[0055]
In addition, the write information measurement unit
68 receives a supply of the write start time Ts and the
15 write end time Te of the even-numbered field image neven
from the write control unit 64.
[0056]
As illustrated in Fig. 3, the write information
measurement unit 68 measures the write preparation time
20 Xneven (= Vblank (n-leven)- Ts) based on the write start
time Ts from the write control unit 64 and the
predetermined display timing Vblank (n-leven.)
[0057]
Further, as illustrated in Fig. 3, for example, the
25 write information measurement unit 68 measures the buffer
write time Pneven (= Te - Ts) based on the write start
time Ts and the write end time Te from the write control
unit 64.
100581
30 The write information measurement unit 68 also
measures a write preparation time XnOdd and a buffer write
time Pnodd of the odd-numbered field image nodd in the same
manner for the odd-numbered field image nodd.
[0059]
The write information measurement unit 68 supplies
5 the write preparation time Xneven and the buffer write
time Pneven measured per even-numbered field image neven,
and the write preparation time Xnodd and the buffer write
time Pnodd measured per odd-numbered field image nodd to
the write information storage unit 69 to store.
10 [0060]
Hereinafter, when an even-numbered field image neven
and an even-numbered field image neven do not need to be
distinguished, the even-numbered field image is simply
referred to as a "field image mu.
15 [0061]
In addition, m indicates the field image m is
displayed m-th. That is, the even-numbered field image
neven is an image which is displayed 2n-th, and the oddfield
image nodd is an image which is displayed 2n-1-th.
20 When 2n = m is true, the even-numbered field image neven
is an image which is displayed m-th, and the odd-numbered
field image nodd is an image which is displayed m-1-th.
[0062]
Hence, when m is even, the field image m is an
25 even-numbered field image which is displayed m-th, and,
when m is odd, the field image m is an odd-numbered field
image which is displayed m-th.
[0063]
Further, the write preparation time Xnodd or Xneven
30 of the field image m will be referred to as a "write
preparation time Xm", and the buffer write time hOdord
SP32 6800WOOO
Pn,,,, of the field image m will be referred to as the
buffer write time Pm.
[0064]
The write information storage unit 69 stores the
write preparation time Xrn and the buffer write time Pm
from the write information measurement unit 68 as write
information.
[0065]
The threshold calculation unit 70 performs
threshold calculation processing of calculating a
threshold time Sth and a delay buffer maximum time (YZth)
which will be described below, based on the write
information stored in the write information storage unit
69. In addition, this threshold calculation processing
will be described in detail with reference to Figs. 4 to
7.
[0066]
The threshold calculation unit 70 supplies the
threshold time Sth and the delay buffer maximum time (YZth)
calculated by threshold calculation processing, to
the write information measurement unit 68.
[0067]
The operation unit 71 is, for example, an operation
button operated by a user, and supplies an operation
signal matching a user operation to the control unit 72.
[0068]
The control unit 72 controls each of the RTP
reception unit 61, the packet assemble unit 62, the
decoding unit 63, the write control unit 64, the display
control unit 66, the write information measurement unit
68 and the threshold calculation unit 70 based on, for
example, an operation signal from the operation unit 71.
[0069]
[Details of Threshold Calculation Processing]
Next, the threshold calculation processing
5 performed by the threshold calculation unit 70 will be
described with reference to Figs. 4 to 7.
[0070]
Fig. 4 illustrates an example of a distribution of
the write preparation times Xm stored in the write
10 information storage unit 69.
[0071]
In Fig. 4, a horizontal axis indicates the write
preparation time Xm, and a vertical axis indicates the
frequency of the write preparation time Xm.
15 [0072]
The threshold calculation unit 70 generates X
distribution information indicating the distribution of
the write preparation times Xm as illustrated in Fig. 4
based on the write preparation time Xm stored in the
20 write information storage unit 69.
[0073]
Further, the threshold calculation unit 70
calculates a threshold Xth for distinguishing between the
write preparation times Xm of top a (for example, a =
25 95) percent in case that the write preparation times Xm
are arranged in an ascending order and the write
preparation times Xm of the rest of bottom (100 - a)
percent based on X distribution information of the write
preparation times Xm.
30 [0074]
Meanwhile, this threshold Xth takes a value which
is equal to or more than a maximum value of the write
preparation times Xm of top a (for example, a = 95)
percent in case that the write preparation times Xm are
arranged in the ascending order, and which is less than a
5 minimum value of the write preparation times Xm of bottom
(100 - a) percent. In addition, the value of a is
determined in advance according to a user operation.
[0075]
Next, Fig. 5 illustrates an example of a
10 distribution of buffer write times Pm stored in the write
information storage unit 69.
[0076]
In Fig. 5, a horizontal axis indicates the buffer
write time Pm, and a vertical axis indicates the
15 frequency of the buffer write time Pm.
[0077]
The threshold calculation unit 70 generates P
distribution information indicating the distribution of
the buffer write times Pm as illustrated in Fig. 5 based
20 on a plurality of buffer write times Pm stored in the
write information storage unit 69.
[0078]
Further, the threshold calculation unit 70
calculates a threshold Pth for distinguishing between the
25 buffer write times Pm of top a percent in case that the
buffer write times Pm are arranged in an ascending order
and the buffer write times Pm of the rest of bottom (100
- a) percent based on P distribution information of the
buffer write times Pm.
30 [0079]
Meanwhile, this threshold Pth takes a value which
is equal to or more than a maximum value of the buffer
write times Pm of top a percent in case that the buffer
write times Pm are arranged in the ascending order, and
which is less than a minimum value of the buffer write
5 times Pm of bottom (100 - a) percent.
[0080]
Next, Fig. 6 illustrates an example where the
threshold calculation unit 70 calculates the threshold
time Sth and the delay buffer maximum time (Y-Zth) .based
10 on the calculated threshold Xth and threshold Pth.
[ 00811
As illustrated in Fig. 6, the threshold calculation
unit 70 calculates the threshold Zth according to
equation 1 based on the threshold Xth, the threshold Pth
15 and the predetermined display interval Vblank Interval.
Zth = (3/2) x Vblank Interval - (Xth + Pth) (1)
[ 0 0 8 2 1
In addition, in Fig. 6, an expected write time 1/60
is a write time of the field image m which is expected
20 when, for example, writing of data is not delayed in the
write control unit 64.
[0083]
This expected write time 1/60 is determined
according to, for example, the time required to display
25 the field image m. In this case, the display unit 67
displays the field image m in the display time 1/60.
Hence, for example, the expected write time is also 1/60
likewise. In addition, when the display unit 67 displays
the field image m in a display time l/a, for example, an
30 expected write time is l/a.
[0084]
Further, as illustrated in Fig. 6, the threshold
calculation unit 70 calculates the threshold time Sth
according to following equation (2) based on the
threshold Zth and the threshold Xth.
5 Sth = Xth + Zth (2 1
[0085]
Meanwhile, the threshold time Sth refers to a write
preparation time at which writing of the field image m
performed using the threshold Pth for the write time is
10 finished at a display end time at which the field image m
is displayed in synchronization with a display timing at
which the field image m needs to be displayed.
[0086]
More specifically, in Fig. 6, for example, the
15 threshold time Sth refers to a write preparation time at
which writing of the even-numbered field image n,,,,
performed using the threshold Pth for the write time is
finished at a display end time at which the even-numbered
field image n,,,, is displayed in synchronization with the
20 display timing Vblank (n,,,,) .
[0087]
Further, for example, the threshold calculation
unit 70 calculates a required time Y of the field image m
based on the threshold Xth and the display interval
25 Vblank Interval.
[0088]
Meanwhile, the required time Y is statistically a
time required from the write start time Ts to a display
timing (in case of Fig. 6, the display timing Vblank
30 (neven)).
[0089]
That is, as illustrated in Fig. 6, for example, the
threshold calculation unit 70 calculates the required
time Y according to following equation (3) based on the
display interval Vblank Interval of the display timing
5 Vblank (n-l,,,,) and the display timing (n,,,,) and the
threshold Xth.
Y = Vblank Interval - Xth (3)
[0090]
Further, as illustrated in Fig. 6, the threshold.
10 calculation unit 70 calculates the delay buffer maximum
time (Y-Zth) based on the calculated required time Y and
threshold Zth.
[0091]
In addition, although a case has been described
15 with reference to Fig. 6 where Zth 2 0 is true, when Zth
< 0 is true as illustrated in Fig. 7, the threshold time
Sth and the delay buffer maximum time (Y-Zth) are
calculated in the same manner.
[0092]
20 The threshold calculation unit 70 supplies the
calculated threshold time Sth and delay buffer maximum
time (Y-Zth) to the write information measurement unit 68.
[0093]
The write information measurement unit 68 decides
25 whether or not the write preparation time Xm of the field
image m is the threshold time Sth from the threshold
calculation unit 70 or more according to following
equation (4), and supplies the decision result to the
write control unit 64.
30 Xm 1 Sth (4)
[0094]
The write control unit 64 controls writing of the
field image m in the display buffer 65 according to the
decision result from the write information measurement
unit 68.
5 [0095]
[Details of Write Control performed by Write Control Unit
64 I
Next, details of processing of controlling writing
of the field image m in the write control unit 64
10 according to a decision result from the write information
measurement unit 68 will be described with reference to
Figs. 8 to 13.
[0096]
Cases will be more specifically described with
15 reference to Figs. 8 to 13 where the field image m is the
even-numbered field image n,,,,, and the write preparation
time Xm is the write preparation time Xn,,,,. In addition,
the same applies to cases where the field image m is the
odd-numbered field image nodd and the write preparation
20 period Xm is the write preparation time Xnodd, and
therefore these cases will not be described.
[ 0 0 97 ]
Fig. 8 illustrates an example where the write
control unit 64 controls writing when equation (4) is
25 satisfied.
[0098]
In addition, in Fig. 8, a line segment 81
represents a write time required to start writing the
even-numbered field image n,,,, in the display buffer 65
30 after the write preparation time Xn,,,, passes.
[0099]
Meanwhile, although the write time represented by
the line segment 81 actually changes according to, for
example, a time required for transfer or a time required
for decoding, the write time is statistically found based
5 on the write preparation time Xrn and an allowable delay
time Pm. That is, for example, the write time 81
indicates an upper limit of the write time of the field
image m received at the probability of the a percent.
[OlOO]
10 Further, in Fig. 8, a line segment 82 represents a
display time required to display the even-numbered field
image neven in synchronization with the display timing
Vblank (neven)a t which the even-numbered field image neven
needs to be displayed.
15 [OlOl]
Furthermore, in Fig. 8, a line segment 83
represents a write time required to start writing the
even-numbered field image neven by providing delay of a
delay time B from a time when the write preparation time
[0102]
Meanwhile, the write time represented by the line
segment 83 is an expected write time 1/60. This is
because, in the write time represented by the line
25 segment 83, the even-number field image neven written in
the display buffer 65 is not transferred from the
transmission apparatus 21, and decoded and written in the
display buffer 65, but is the even-numbered field image
neven held in the delay buffer 64a.
30 [0103]
In Fig. 8, Xneven 1 Xth + Zth (= Sth) is true, and
equation (4) is satisfied. A case will be described
where, after the write preparation time Xneven passes,
writing of the even-numbered field image neve, in the
display buffer 65 is started.
5 [0104]
In this case, the line segment 81 and the line
segment 82 intersect as illustrated in Fig. 8, for
example, lines (i2L) subsequent to a line number L among
of lines (i) of a line number i in the even-numbered
10 field image neve, is written in the display buffer 65 at
or after the display time of the lines (i2L).
[0105]
In addition, the line (i=L) is a line written in
the display buffer 65 when the line segment 81 and the
15 line segment 82 intersect.
[0106]
Hence, in Fig. 8, the lines (i2L) subsequent to,
for example, the line number L cannot be displayed at a
display time represented by the line segment 82.
20 [0107]
Consequently, when obtaining the decision result
that equation (4) is satisfied from the write information
measurement unit 68, the write control unit 64 causes the
built-in delay buffer 64a to hold the even-numbered field
25 image neven from the decoding unit 63 until the display
timing Vblank (neven)p asses.
[0108]
Further, the write control unit 64 starts writing
the even-numbered field image neven held in the delay
30 buffer 64a, in the display buffer 65 after the display
timing Vblank (neve,) passes.
[0109]
That is, as illustrated in Fig. 8, for example, the
write control unit 64 starts writing the even-numbered
field image n,,,, by providing delay of a delay buffer
5 time B from a time when the write preparation time Xn,,,,
passes.
[OllO]
In addition, the write control unit 64 delays start
of writing by the delay time B by, for example, using the
10 built-in delay buffer 64a. Further, as illustrated in
Fig. 9, a delay buffer maximum time Bmax which is a
maximum time of the delay buffer time B is a delay buffer
time B in case that Xn,,,, = Xth + Zth (= Sth) is true,
and is (Y-Zth).
15 [Olll]
This delay buffer maximum time Bmax (= Y - Zth) is
calculated by the threshold calculation unit 70, and is
supplied to the write control unit 64 through the write
information measurement unit 68.
20 [0112]
Consequently, the write control unit 64 can
calculate a maximum buffer capacity which is required to
delay writing and a remaining buffer capacity which is
not required to delay writing, based on the delay buffer
25 maximum time Bmax to be supplied.
[0113]
Hence, the write control unit 64 can secure the
maximum buffer capacity which is required to delay start
of writing, and use the remaining buffer capacity for
30 another processing.
[0114]
Further, when, for example, an odd-numbered field
image n+lodd is not displayed at a next display timing
Vblank (n+lOdd),t he even-numbered field image n,,,,
written at the write time indicated by the line segment
5 83 is displayed at the display timing Vblank (n+lodd).
[0115]
For example, when a line segment 81' representing a
write time of the odd-numbered field image n+lodd and a
line segment 82' representing a display time of the odd-
10 numbered field image n+lodd intersect in the odd-numbered
field image n+lodd as illustrated in Fig. 10, the write
control unit 64 writes the odd-numbered field image n+lodd
at a write time represented by a line segment 83' by
delaying start of writing.
15 [0116]
In this case, similar to the case described with
reference to Fig. 8, the odd-numbered field image n+lodd
is not displayed at the display time indicated by the
line segment 82'. Consequently, the even-numbered field
20 image n, which has already been written at the write
time represented by the line segment 83 is displayed at
the display time represented by the line segment 82'.
[0117]
In addition, when, for example, the even-numbered
25 field image n,,,, is displayed in synchronization with the
display timing Vblank (n,,,,), and the odd-numbered field
image n+lodd is not displayed at the display timing Vblank
(n+lOdd),i t is possible to display the odd-numbered field
image n,,,, held in the display buffer 65 at the display
30 timing Vblank (n+lodd.)
[0118]
Further, when a field image which needs to be
displayed at the display timing Vblank (n+lodd) and, in
addition, a display timing (for example, the display
timing Vblank (ntl,,,,)) subsequent to the display timing
5 Vblank (n+lodd) is not displayed, the even-numbered field
image n,,,, may be displayed at this display timing.
[0119]
Next, Fig. 11 illustrates an example where the
write control unit 64 controls writing when equation (4)
10 is not satisfied.
[0120]
In Fig. 11, Xn,,,, < Xth + Zth (= Sth) is true and,
when equation (4) is not satisfied, the line segment 81
and the line segment 82 do not statistically intersect.
15 In this case, the line (i) of the line number i is
written in the display buffer 65 before the display time
of the line (i).
[0121]
Hence, when obtaining the decision result that
20 equation (4) is not satisfied from the write information
measurement unit 68, the write control unit 64 starts
writing of the even-numbered field image n,,,, in the
display buffer 65 when the write preparation time Xn,,,,
passes.
25 [0122]
Further, the display control unit 66 causes the
display unit 67 to display the even-numbered field image
n,,,, written in the display buffer 65 in synchronization
with the display timing Vblank (n,,,,) .
30 [0123]
In addition, when equation (4) is satisfied, the
line segment 81 and the line segment 82 do not
statistically intersect as described above. However, as
illustrated in Fig. 12, the line segment 81 and the line
segment 82 actually intersect in some cases.
5 [0124]
In this case, for example, lines (i2L) subsequent
to the line number L among the lines (i) of the line
number i is written in the display buffer 65 at or after
the display time of the lines (i2L).
10 [0125]
Hence, in a case illustrated in Fig. 12, for
example, the lines (i2L) subsequent to the line number L
cannot be displayed at a display time at which the lines
(i2L) need to be displayed.
15 [0126]
Hence, when equation (4) is not satisfied, whether
or not a write time of the line (i) comes at or after the
display time of the line (i) is desirably monitored.
[0127]
20 Next, Fig. 13 illustrates an example of a method of
monitoring in the write information measurement unit 68
whether or not the write time of the line (i) comes at or
after the display time of the line (i) when equation (4)
is not satisfied.
25 [0128]
To prevent the write time of the line (i) from
coming at or after the display time of the line (i), a
write time Ti of the line (i) needs to come earlier than
a display time Ti' of the line (i) as shown in following
30 equation (5).
Ti < Ti' (5
[0129]
In addition, the display time Ti' can be
represented by following equation (6).
Ti' = i x Vblank Interval/(2 x I) (6)
5 [0130]
Meanwhile, Vblank Interval/2 indicates a display
time required to display the entire field image m (the
even-numbered field image n,,,, in case of Fig. 13).
Further, the total number of lines I indicates the total
10 number of lines of the field image m (I = 540 in case of
Fig. 13). Hence, Vblank Interval/2 x 1/I (= Vblank
Interval/(2 x I)) represents the display time required to
display one line of the field image m. Therefore, i x
Vblank Interval/(2 x I) = Ti' indicates the display time
15 required to display the number of lines i.
[0131]
In addition, when the write time Ti comes earlier
than a time t3 which is the display timing Vblank (n,,,,),
that is, when Ti < t3 is true as illustrated in Fig. 13,
20 equation (5) is satisfied at all times. Consequently, it
is not necessary to decide whether or not equation (5) is
satisfied until the start time t3 arrives.
[0132]
In Fig. 13, the lines (1) to (L) written at write
25 times T1 to Ti=L which satisfy equation (5) are displayed
on the display unit 67 at display times TI1 to Ti=L' in
synchronization with the display timing Vblank (n,,,,).
[0133]
Further, display times Ti=L+l' to have already
30 passed at write times Ti=L+l to Ti=54o1 and therefore the
rest of lines (L+1) to (540) lines written at write times
to Ti=540 which do not satisfy equation (5) are not
displayed on the display unit 67 in synchronization with
the display timing Vblank (n,,,,) .
[0134]
5 Meanwhile, after the write time TizS40 passes, the
display buffer 65 holds the 1 to L lines and the lines
(L+1) to (540) lines, that is, the entire even-numbered
field image n,,,,.
[ 0 13 5 ]
10 Hence, similar to the above case of Fig. 10, when,
for example, the odd-numbered field image n+lodd is not
displayed at the display timing Vblank (n+lodd)n ext to
the display timing Vblank (n,,,,) , the even-numbered field
image n,,,, held in the display buffer 65 is displayed at
15 this display timing Vblank (n+lodd).
[0136]
In addition, write information obtained when
writing is performed at the write time indicated by the
line segment 83 as illustrated in Fig. 8 is desirably not
20 used to calculate, for example, the threshold time Sth
without being stored in the write information storage
unit 69.
[0137]
Meanwhile, the threshold calculation unit 70
25 updates the threshold time Sth and the delay buffer
maximum time (Y-Zth) by appropriately performing the
threshold calculation processing. This is because a
transmission time changes according to, for example, a
congestion situation of the network 23. That is,
30 depending on a change in the transmission time, the write
preparation time Xm and the buffer write time Pm used to
calculate the threshold time Sth and the delay buffer
maximum time (Y-Zth) also change.
[0138]
Next, Figs. 14 and 15 illustrate examples of how a
5 transmission time changes according to, for example, a
congestion situation of the network 23.
[0139]
In Figs. 14 and 15, a vertical axis indicates a
packet number indicating each RTP packet of the image
10 data n. Further, a horizontal axis indicates times
required for "capture processing" performed by the
capture unit 41, "coding" processing performed by the
coding unit 42, "packet configuration" processing
performed by the packet configuration unit 43, "transfer"
15 processing of RTP packets performed between the RTP
transmission unit 44 and the RTP reception unit 61
through the network 23, "packet assembly" processing
performed by the packet assemble unit 62 and "decoding"
processing performed by the decoding unit 63 with respect
20 to data configuring the image data n.
[0140]
As illustrated in Figs. 14 and 15, the time
required for the "transfer" processing becomes
significantly different depending on a situation of the
25 network 23. That is, when congestion of the network 23
is relatively a little, the time required for the
"transfer" processing" is short as illustrated in Fig. 14,
and, when congestion of the network 23 is relatively
significant, the time required for the "transfer"
30 processing is long as illustrated in Fig. 15.
[0141]
Hence, when the time required for the "transfer"
processing and, moreover, the transmission time change
depending on, for example, the congestion situation of
the network 23, the write preparation time Xm and the
5 buffer write time Pm also change, and therefore the
threshold calculation unit 70 needs to appropriately
perform threshold calculation processing.
[0142]
[Explanation of Operation of Reception Apparatus 221
10 Next, display control processing performed by the
reception apparatus 22 will be described with reference
to the flowchart in Fig. 16.
[0143]
In step S21, the RTP reception unit 61 receives RTP
15 packets transmitted from the RTP transmission unit 44
through the network 23, and supplies the RTP packets to
the packet assemble unit 62.
[0144]
In step S22, the packet assemble unit 62 generates
20 decoding target coded data by assembling the RTP packets
from the RTP reception unit 61, and supplies the coded
data to the decoding unit 63.
101451
In step S23, the decoding unit 63 applies decoding
25 processing supporting coding processing performed in the
coding unit 42, to the coded data from the packet
assemble unit 62, and supplies the resulting image data
to the write control unit 64. Meanwhile, for decoding
processing, decoding processing of decoding and
30 stretching data by, for example, inverse transform of
wavelet transform is adopted.
101461
The write control unit 64 supplies a write start
time Ts at which writing in the display buffer 65 is
started and a write end time Te at which writing is
5 finished, to the write information measurement unit 68
per field image m configuring the image data from the
decoding unit 63. Meanwhile, the field image m is one of
an odd-numbered field image and an even-numbered field
image, and is an image which is displayed m-th.
10 [0147]
In addition, the write control unit 64 supplies the
field image m configuring the image data from the
decoding unit 63 to the display buffer 65 to store (write
in) in step S27, S30 or S34 described below.
[0148]
In step 524, the write information measurement unit
68 measures the write preparation time Xm of the field
image m based on the write start time Ts from the write
control unit 64 and the predetermined display timing
Vblank, and supplies the write preparation time Xm to the
write information storage unit 69 to store.
[0149]
In step S25, the write information measurement unit
68 measures the buffer write time Pm of the field image m
25 based on the disclosure time Ts and the end time Te from
the write control unit 64, and supplies the buffer write
time Pm to the write information storage unit 69 to store.
[0150]
In step S26, the write information measurement unit
30 68 decides whether or not the write preparation time Xrn
measured by processing in step S24 is the threshold time
Sth or more calculated by processing in step S36
immediately before according to equation (4). In
addition, when the processing in step S36 is not yet
performed, for example, the threshold time Sth takes a
5 predetermined value.
[0151]
In step S26, when deciding that the write
preparation time Xrn is the threshold time Sth or more,
the write information measurement unit 68 supplies the
10 decision result to the write control unit 64, and
processing proceeds to step S27.
[0152]
Further, in step S27, when obtaining the decision
result that the write preparation time Xm is the
15 threshold time Sth or more from the write information
measurement unit 68, the write control unit 64 delays
start of writing of the field image m in the display
buffer 65 by using the built-in delay buffer 64a.
[0153]
20 More specifically, when, for example, the field
image m is the even-numbered image n,,,,, the write
control unit 64 delays start of writing of the evennumbered
field image n,,,, in the display buffer 65
subsequent to the display timing Vblank (n,,,,) as
25 described with reference Fig. 8.
[0154]
In step S28, if a field image m-1 has already been
written in the display buffer 65 in previous step S27 or
step S34 described below, the display control unit 66
30 reads the field image m-1 from the display buffer 65 and
displays the field image m-1 instead of the field image m.
More specifically, when, for example, the field
image m is the even-numbered field image n,,,, and the
field image m-1 is the odd-numbered field image nodd, the
5 display control unit 66 causes the display unit 67 to
display the odd-numbered field image nodd which has
already been written in the display buffer 65 in
synchronization with the display timing Vblank (n,,,,).
[0156]
10 In step 529, the write control unit 64 calculates a
buffer capacity which is not used in the delay buffer 64a
based on the delay buffer maximum time (Y-Zth) which has
been calculated in step S36 immediately before.
[0157]
Further, the write control unit 64 uses for another
processing the buffer capacity which is not used in the
delay buffer 64a. By this means, it is possible to
efficiently use the buffer capacity which is not used in
the delay buffer 64a.
20 [0158]
Meanwhile, in step S26, when deciding that the
write preparation time Xm is not (is less than) the
threshold time Sth or more, the write information
measurement unit 68 supplies the decision result to the
25 write control unit 64 and processing proceeds to step S30
[0159]
In step S30, when obtaining the decision result
that the write preparation time Xm is less than the
threshold time Sth from the write information measurement
30 unit 68, the write control unit 64 starts writing the
field image m in the display buffer 65 when the write
preparation time Xrn passes.
[0160]
Further, in step S31, the display control unit 66
makes the field image m written in the display buffer 65
5 be displayed.
[0161]
More specifically, for example, when the field
image m is the even-numbered field image n,,,,, the
display control unit 66 causes the even-numbered field
10 image n,,,,, written in the display buffer 65, to be
displayed in synchronization with the display timing
Vblank (n,,,,) .
[0162]
In step S32, in parallel to processing in step S30
15 and step ,531, the write information measurement unit 68
decides whether or not the write time of each line (i) of
the field image m arrives at or after the display time of
the line (i), based on whether or not equation (5) is
satisfied.
20 [0163]
In step S32, when the write information measurement
unit 68 does not decide that the write time of each line
(i) of the field image m arrives at or after the display
time of the line (i) until the processing in step S30 and
25 step S31 are finished, processing proceeds to step S35.
101641
Further, in step S32, when the write information
measurement unit 68 does not decide that the write time
of each line (i) of the field image m arrives at or after
30 the display time of the line (i) until the processing in
step S30 and step S31 are finished, processing proceeds
to step S33.
[0165]
In step S33, the display control unit 66 skips
displaying the rest of portions of the field image m
5 which is written in the display buffer 65 at the write
time which does not satisfy equation (5), and processing
proceeds to step S34.
[0166]
In addition, part of the field image m which is
10 written at the write time which satisfies equation (5) is
displayed by processing in step S31.
[0167]
In step S34, the display control unit 66 causes the
write control unit 64 to write the rest of portions of
15 the field image m in the display buffer 65 at the write
time which does not satisfy equation (5). By this means,
part and the rest of the field image m, that is, the
entire field image m, is written in the display buffer 65.
101681
20 In step S35, the threshold calculation unit 70
decides whether or not a clock time clocked by a built-in
clock unit (not illustrated) passes a predetermined time,
and, when deciding that the clock time does not pass the
predetermined time, returns processing to step S21, and
25 the same processing is performed subsequently.
[0169]
Further, in step S35, when it is decided that the
clock time passes the predetermined time, processing
proceeds to step S36, and the threshold calculation unit
30 70 performs threshold calculation processing of
calculating the threshold time Sth and the delay buffer
maximum time (Y-Zth) based on the write preparation time
Xm and the buffer write time Pm stored in the write
information storage unit 69. Furthermore, the threshold
calculation unit 70 supplies the calculated threshold
5 time Sth and delay buffer maximum time (Y-Zth) to the
write information measurement unit 68.
[0170]
In step S36, the threshold calculation unit 70
performs the threshold calculation processing, and then
10 deletes the write preparation time Xm and the buffer
write time Pm stored in the write information storage
unit 69. Further, the threshold calculation unit 70
resets clocking of the built-in clock unit, starts
clocking again and returns processing to step S21, and
15 the same processing is performed subsequently.
[0171]
[Details of Threshold Calculation Processing]
Next, details of the threshold calculation
processing in step S36 in Fig. 16 will be described with
20 reference to a flowchart in Fig. 17.
101721
In step S41, the threshold calculation unit 70
reads the write preparation times Xm from the write
information storage unit 69, and calculates X
25 distribution information representing a distribution of
the read write preparation times Xm.
[0173]
In step S42, the threshold calculation unit 70
calculates the threshold Xth based on the X distribution
30 information calculated in step S41.
[0174]
In step S43, the threshold calculation unit 70
calculates the required time Y according to equation ( 3 )
based on the display interval Vblank Interval and the
threshold Xth.
5 [0175]
In step S44, the threshold calculation unit 70
reads the buffer write times Pm from the write
information storage unit 69, and calculates P
distribution information representing a distribution of
10 the read buffer write times Pm.
[0176]
In step S45, the threshold calculation unit 70
calculates the threshold Pth based on the P distribution
information calculated in step S44.
15 [0177]
In step S46, the threshold calculation unit 70
calculates the threshold Zth according to equation ( 1 )
based on the threshold Xth calculated in step S42, the
threshold Pth calculated in step S45 and the display
20 interval Vblank Interval.
[0178]
In step S47, the threshold calculation unit 70
calculates the threshold time Sth according to equation
(2) based on the threshold Xth calculated in step S42 and
25 the threshold Zth calculated in step S46.
[0179]
In step S48, the threshold calculation unit 70
calculates a delay buffer maximum time (Y-Zth) based on
the required time Y calculated in step 543 and the
30 threshold Zth calculated in step S46.
[01801
Thus, the threshold calculation processing is
finished, and then the processing is returned to step S36
in Fig. 16. Further, processing returns from step S36 to
step S21, and the same processing is performed
5 subsequently.
[0181]
As described above, according to the display
control processing, when, for example, the write
preparation time Xm = Xn,,,, of the even-numbered field
10 image n,,,, satisfied equation (4) (Xm 2 Sth) , start of
writing of the even-numbered field image n,,,, is delayed
until the display timing Vblank (n,,,,) passes.
[0182]
Further, at the display timing Vblank (n,,,,), a
15 field image (for example, the odd-numbered field image
no&) which needs to be displayed prior to the evennumbered
field image n,,,, is displayed instead of the
even-numbered field image n,,,,.
[0183]
20 Furthermore, according to the display control
processing, when, for example, the write preparation time
Xm = Xn,,,, of the even-numbered field image n,,,, does not
satisfy equation (4) (Xm 2 Sth), the even-numbered field
image n,,,, is written at the write time represented by
25 the line segment 81 which does not statistically
intersect the line segment 82.
[0184]
Still further, when equation (4) is not satisfied,
whether or not the line segment 81 intersects the line
30 segment 82 is monitored according to whether or not
equation (5) is satisfied.
[0185]
Moreover, when it is decided that the line segment
81 intersects the line segment 82, part of the evennumbered
field image n,,,, which has already been written
5 is displayed at the display timing Vblank (n,,,,) .
Moreover, by writing the rest of portions of the evennumbered
field image in the display buffer 65, the evennumbered
field image n,,,, held in the display buffer 65
can be displayed at a subsequent display timing when
10 necessary.
[0186]
Consequently, according to the above display
control processing, part of an image is skipped, so that
it is possible to prevent an accident that, for example,
15 distortion of an image occurs.
[ 0 18 7 ]
<2. Modified Example>
With the present embodiment, for example, a threshold
time Sth and a delay buffer maximum time (Y-Zth) are
20 calculated based on write information of a field image m.
[0188]
However, when, for example, a display unit 67
displays an image according to the progressive system, as
illustrated in Fig. 18, image data n is regarded as a
25 progressive image m as is, and, for example, the
threshold time Sth and the delay buffer maximum time (YZth)
are calculated based on write information of the
progressive image m.
[0189]
30 In addition, with the progressive image m, Ti1 in
equation (5) is represented by following equation (6').
Ti' = ixVblank Interval/I (6)
[0190]
Meanwhile, Vblank Interval represents a display
time required to display the entire progressive image m.
5 Further, the total number of lines I represents the total
number of lines of the progressive image m. Hence,
Vblank Interval x 1/I (= Vblank Interval/I) represents
the display time required to display one line of the
progressive image m. Hence, i x Vblank Interval/I = Ti'
10 represents the time required to display the number of
lines i in the progressive image m.
[0191]
Further, when generating X distribution information
representing a distribution of write preparation times Xm
15 illustrated in Fig. 4, a threshold calculation unit 70
generates the X distribution information assuming the
frequency of the write preparation time Xm as 1
irrespectively of a period in which the write preparation
times Xm are measured.
20 [0192]
However, when the period of measurement is more
nearer, the threshold calculation unit 70 may generate
the X distribution information such that a more frequency
is added to the write preparation time Xm. This is
25 because, when the write preparation time Xrn which is
measured more nearer more accurately represents the write
preparation time of the image to be received.
[0193]
The same also applies upon generation of P
30 distribution representing a distribution of buffer write
times Pm as illustrated in Fig. 5.
By this means, the threshold calculation unit 70
can generate the X distribution information which more
accurately reflects a write preparation time of an image
5 to be received, and can generate the P distribution
information which more accurately reflects a buffer write
time of an image to be received.
[0195]
Consequently, the threshold calculation unit 70 can
10 calculate, for example, the more adequate threshold time
Sth and delay buffer maximum time (Y-Zth) from the X
distribution information and the P distribution
information. Consequently, it is possible to prevent an
accident that, for example, distortion of an image occurs
15 when part of the image is skipped.
[0196]
In addition, the present technology can employ the
following configuration.
(1) The display control apparatus includes: a
20 measurement unit which measures a write preparation time
required to start writing a received image in a hold unit
which temporarily holds the image; a write control unit
which controls the writing of the image according to
whether or not the write preparation time is a threshold
25 time or more which represents a write preparation time at
which the writing of the image is finished at a display
end time at which the image is displayed in
synchronization with a display timing at which the image
needs to be displayed; and a display control unit which
30 displays the image written in the hold unit under control
of the write control unit in synchronization with the
display timing by a write time at which the image is
displayable in synchronization with the display timing.
(2) In the display control apparatus according to above
(I), when the write preparation time is the threshold
5 time or more, the write control unit starts the writing
of the image after the display timing passes by delaying
the writing of the image started when the write
preparation time passes.
(3) The display control apparatus according to above
10 (2) further includes a calculation unit which calculates
a maximum value of a buffer capacity used to delay the
writing of the image in the write control unit.
(4) In the display control apparatus according to above
(2) or (3), when writing of a first image which needs to
15 be displayed at a first display timing is started after
the first display timing passes, the display control unit
displays a second image which has been written in the
hold unit under control of the write control unit and
which is different from the first image, in
20 synchronization with the first display timing.
(5) In the display control apparatus according to above
(4), when the writing of the first image is started after
the first display timing passes, the display control unit
displays the second image, writing of which is started
25 after a second display timing which comes earlier than
the first display timing passes, in synchronization with
the first display timing.
(6) In the display control apparatus according to above
(2) or (3), when the write preparation time is less than
30 the threshold time, the write control unit starts writing
the image after the write preparation time passes.
(7) In the display control apparatus according to above
(6), when the writing of the first image which needs to
be displayed at a first display timing is started after
the writing preparation time passes, the display control
5 unit finishes writing part of the first image by a write
time at which the first image is displayable in
synchronization with the first display timing, and, when
writing of the rest of the first image is not finished,
displays the part of the first image written in the hold
10 unit, in synchronization with the first display timing.
(8) In the display control apparatus according to above
(7), when writing of a second image which needs to be
displayed at a second display timing which comes after
the first display timing is started after the second
15 display timing passes, the display control unit displays
the part of the first image and, in addition, the first
image the rest of which has been written, in
synchronization with the second display timing.
(9) The display control apparatus according to above
20 (1) to (8) further includes: another measurement unit
which measures a write time required to write the image;
and a threshold calculation unit which calculates the
threshold time based on a distribution of the write
preparation time and a distribution of the write time,
25 and the write control unit controls the writing of the
image according to whether or not the write preparation
time is the calculated threshold time or more.
[0197]
By the way, the above series of processing can be
30 executed by hardware and can be executed by software.
When a series of processing are executed by software, a
program configuring this software is installed from a
program recording medium to, for example, a computer
implemented in dedicated hardware or a general-purpose
computer which can execute various functions by
5 installing various programs.
[0198]
[Configuration Example of Computer]
Fig. 19 is a block diagram illustrating a
configuration example of hardware of a computer which
10 executes the above series of processing by a program.
[0199]
A CPU (Central Processing Unit) 201 executes
various processing according to a program stored in a ROM
(Read Only Memory) 202 or a storage unit 208. In a RAM
15 (Random Access Memory) 203, for example, programs
executed by the CPU 201 and data are appropriately stored.
These CPU 201, ROM 202 and RAM 203 are mutually connected
through a bus 204.
[0200]
20 The CPU 201 is also connected with an input/output
interface 205 through the bus 204. The input/output
interface 205 is connected with an input unit 206 which
includes, for example, a keyboard, a mouse and a
microphone, and an output unit 207 which includes, for
25 example, a display and a speaker. The CPU 201 executes
various processing in response to an instruction input
from the input unit 206. Further, the CPU 201 outputs a
processing result to the output unit 207.
[0201]
30 The storage unit 208 connected to the input/output
interface 205 includes, for example, a hard disk, and
stores programs executed by the CPU 201 and various items
of data. The communication unit 209 communicates with an
external apparatus through a network such as Internet or
a local area network.
5 [0202]
Further, programs may be acquired through the
communication unit 209, and stored in the storage unit
208.
[0203]
10 When mounted with a removable medium 211 such as a
magnetic disk, an optical disk, a magnetooptical disk or
a semiconductor memory, a drive 210 connected to the
input/output interface 205 drives the removable medium
211 and acquires, for example, a program or data recorded
15 therein. The acquired program or data is transferred to
and stored in the storage unit 208 when necessary.
102041
As illustrated in Fig. 19, a recording medium which
records (stores) a program which is installed in a
20 computer and can be executed by the computer includes the
removable medium 211 which is a package medium including,
for example, a magnetic disk (including a flexible disk),
an optical disk (CD-ROM (Compact Disc-Read Only Memory)
or a DVD (Digital Versatile Disc)), a magnetooptical disk
25 (including MD (Mini-Disc)) or a semiconductor memory, or
a hard disk which configures the ROM 202 which
temporarily or permanently stores the program or the
storage unit 208. A program is recorded in a recording
medium by utilizing a wired or wireless communication
30 medium such as a local area network, Internet or digital
satellite broadcasting through the communication unit 209
which is an interface such as a router or a modem when
necessary.
[0205]
In addition, the steps for describing the above
5 series of processing in this description naturally
include processing performed in a time series along the
disclosed order and also include processing executed in
parallel or individually if not necessarily executed in a
time series.
10 [0206]
Further, the embodiment of the present disclosure
is by no means limited to the above embodiment, and can
be variously changed within a scope which does not
deviate from the spirit of the present disclosure.
15
REFERENCE SIGNS LIST
[0207]
22 Reception apparatus
61 RTP reception unit
20 62 Packet assemble unit
6 3 Decoding unit
6 4 Write control unit
64a Delay buffer
6 5 Display buffer
25 66 Display control unit
6 7 Display unit
6 8 Write information measurement unit
69 Write information storage unit
70 Threshold calculation unit
30 71 Operation unit
72 Control unit

CLAIMS
1. A display control apparatus comprising:
a measurement unit which measures a write
5 preparation time required to start writing a received
image in a hold unit which temporarily holds the image;
a write control unit which controls the writing of
the image according to whether or not the write
preparation time is a threshold time or more which
10 represents a write preparation time at which the writing
of the image is finished at a display end time at which
the image is displayed in synchronization with a display
timing at which the image needs to be displayed; and
a display control unit which displays the image
15 written in the hold unit under control of the write
control unit in synchronization with the display timing
by a write time at which the image is displayable in
synchronization with the display timing.
20 2. The display control apparatus according to claim 1,
wherein, when the write preparation time is the threshold
time or more, the write control unit starts the writing
of the image after the display timing passes by delaying
the writing of the image started when the write
25 preparation time passes.
3. The display control apparatus according to claim 2,
further comprising a calculation unit which calculates a
maximum value of a buffer capacity used to delay the
30 writing of the image in the write control unit.
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SP326800WO00
4. The display control apparatus according to claim 2,
wherein, when writing of a first image which needs to be
displayed at a first display timing is started after the
first display timing passes, the display control unit
5 displays a second image which has been written in the
hold unit under control of the write control unit and
which is different from the first image, in
synchronization with the first display timing.
10 5. The display control apparatus according to claim 4,
wherein, when the writing of the first image is started
after the first display timing passes, the display
control unit displays the second image, writing of which
is started after a second display timing which comes
15 earlier than the first display timing passes, in
synchronization with the first display timing.
6. The display control apparatus according to claim 2,
wherein, when the write preparation time is less than the
20 threshold time, the write control unit starts writing the
image after the write preparation time passes.
7. The display control apparatus according to claim 6,
wherein, when the writing of the first image which needs
25 to be displayed at a first display timing is started
after the writing preparation time passes, the display
control unit finishes writing part of the first image by
a write time at which the first image is displayable in
synchronization with the first display timing, and, when
30 writing of the rest of the first image is not finished,
displays the part of the first image written in the hold
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SP326800WO00
unit, in synchronization with the first display timing,
8. The display control apparatus according to claim 7,
wherein, when writing of a second image which needs to be
5 displayed at a second display timing which comes after
the first display timing is started after the second
display timing passes, the display control unit displays
the part of the first image and, in addition, the first
image the rest of which has been written, in
10 synchronization with the second display timing.
9. The display control apparatus according to claim 1,
further comprising:
another measurement unit which measures a write
15 time required to write the image; and
a threshold calculation unit which calculates the
threshold time based on a distribution of the write
preparation time and a distribution of the write time,
wherein the write control unit controls the writing
20 of the image according to whether or not the write
preparation time is the calculated threshold time or more.
10. A display control method to be performed by a
display control apparatus which displays a received image,
25 the method comprising:
a measurement step of measuring a write preparation
time required to start writing a received image in a hold
unit which temporarily holds the image;
a write control step of controlling the writing of
30 the image according to whether or not the write
preparation time is a threshold time or more which
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SP326800WO00
represents a write preparation time at which the writing
of the image is finished at a display end time at which
the image is displayed in synchronization with a display
timing at which the image needs to be displayed; and
5 a display control step of displaying the image
written in the hold unit under control of the write
control unit in synchronization with the display timing
by a write time at which the image is displayable in
synchronization with the display timing.
10
11. A program for causing a computer to function as:
a measurement unit which measures a write
preparation time required to start writing a received
image in a hold unit which temporarily holds the image;
15 a write control unit which controls the writing of
the image according to whether or not the write
preparation time is a threshold time or more which
represents a write preparation time at which the writing
of the image is finished at a display end time at which
20 the image is displayed in synchronization with a display
timing at which the image needs to be displayed; and
a display control unit which displays the image
written in the hold unit under control of the write
control unit in synchronization with the display timing
25 by a write time at which the image is displayable in
synchronization with the display timing.