CLIAMS:We claim:
1. A method for enabling a user to access at least one video from a Digital Video Recording (DVR) network, the method comprising of
checking at least one event occurring in a video stream by a DVR management module, on the user sending a request to the DVR management module and the request comprises of the at least one event;
calculating a start time and a stop time for the at least one event in the video stream by the DVR management module;
obtaining at least one video clip from the video stream by the DVR management module based on the start time and the stop time;
creating a playlist by the DVR management module, wherein the playlist comprises of at least one video clip related to at least one event;
sending the playlist and associated information by the DVR management module to a user device; and
streaming the playlist to the user device, based on inputs from the user.
2. The method, as claimed in claim 1, wherein the method further comprises of
generating an event by an event generator;
sending the generated event and event type by the event generator to the DVR management module; and
saving the generated event, the event type and time stamp associated with the event in a database by the DVR management module.
3. The method, as claimed in claim 1, wherein the request from the user comprises of a time duration during which the at least one event occurred.
4. The method, as claimed in claim 1, wherein obtaining at least one video clip from the video stream by the DVR management module based on the start time and the stop time comprises of
querying for recorded file names for a camera associated with the DVR network corresponding to the start time and the stop time;
calculating stream times by the DVR management module based on the file names; and
adding an entry to the playlist by the DVR management module.
5. The method, as claimed in claim 1, wherein streaming the playlist to the user device further comprises of
reading and parsing the playlist and the associated information by the user device;
creating a timeline by the user device based on the associated information;
sending a request for file headers corresponding to the first entry in the playlist by the user device to a DVR system; wherein the request comprises of Byte range headers;
sending a request for the video file corresponding to the start time and the stop time to the DVR system by the user device, on the user device receiving the file headers from the DVR system;
playing the video file by the user device, on the user device receiving the video file from the DVR system.
6. The method, as claimed in claim 5, wherein streaming the playlist to the user device further comprises of
checking if filename of a next entry in the playlist is same as filename of previous entry by the user device, on the user device detecting at least one other entry in the playlist; and
sending only byte range request to the DVR system by the user device, if filename of a next entry in the playlist is same as filename of previous entry by the user device.
7. A system for enabling a user to access at least one video from a Digital Video Recording (DVR) network, the system comprising of a DVR management module, at least one user device and a DVR system, wherein
the DVR management module is configured for
checking at least one event occurring in a video stream, on the user sending a request to the DVR management module and the request comprises of the at least one event;
calculating a start time and a stop time for the at least one event in the video stream;
obtaining at least one video clip from the video stream based on the start time and the stop time;
creating a playlist, wherein the playlist comprises of at least one video clip related to at least one event;
sending the playlist and associated information to the user device; and
the user device configured for
streaming the playlist, based on inputs from the user.
8. The system, as claimed in claim 7, wherein the system further comprises of at least one event generator, wherein
the at least one event generator is configured for
generating an event; and
sending the generated event and event type to the DVR management module; and
the DVR management module is further configured for
saving the generated event, the event type and time stamp associated with the event in a database.
9. The system, as claimed in claim 7, wherein the DVR management module is further configured for obtaining at least one video clip from the video stream based on the start time and the stop time by
querying for recorded file names for a camera associated with the DVR network corresponding to the start time and the stop time;
calculating stream times based on the file names; and
adding an entry to the playlist.
10. The system, as claimed in claim 7, wherein the user device is configured for streaming the playlist to the user device by
reading and parsing the playlist and the associated information;
creating a timeline based on the associated information;
sending a request for file headers corresponding to the first entry in the playlist to the DVR system; wherein the request comprises of Byte range headers;
sending a request for the video file corresponding to the start time and the stop time to the DVR system, on the user device receiving the file headers from the DVR system;
playing the video file, on the user device receiving the video file from the DVR system.
11. The system, as claimed in claim 10, wherein the user device is configured for streaming the playlist to the user device by
checking if filename of a next entry in the playlist is same as filename of previous entry, on the user device detecting at least one other entry in the playlist; and
sending only byte range request to the DVR system, if filename of a next entry in the playlist is same as filename of previous entry by the user device.
12. A Digital Video Recording (DVR) management module in a DVR network, the DVR management module configured for
checking at least one event occurring in a video stream, on a user sending a request to the DVR management module and the request comprises of the at least one event;
calculating a start time and a stop time for the at least one event in the video stream;
obtaining at least one video clip from the video stream based on the start time and the stop time;
creating a playlist, wherein the playlist comprises of at least one video clip related to at least one event; and
sending the playlist and associated information to the user device.
13. The DVR management module, as claimed in claim 12, wherein the DVR management module is further configured for
saving a generated event, an event type and a time stamp associated with the event in a database, on receiving the generated event and the event type from an event generator.
14. The DVR management module, as claimed in claim 12, wherein the DVR management module is further configured for obtaining at least one video clip from the video stream based on the start time and the stop time by
querying for recorded file names for a camera associated with the DVR network corresponding to the start time and the stop time;
calculating stream times based on the file names; and
adding an entry to the playlist.
15. A user device for enabling a user to access at least one video from a Digital Video Recording (DVR) network, the user device is configured for
enabling the user to send a request to the DVR management module, wherein the request comprises of at least one event;
reading and parsing a playlist and associated information received from the DVR management module;
creating a timeline based on the associated information;
sending a request for file headers corresponding to the first entry in the playlist to a DVR system; wherein the request comprises of Byte range headers;
sending a request for the video file corresponding to the start time and the stop time to the DVR system, on the user device receiving the file headers from the DVR system; and
playing the video file, on the user device receiving the video file from the DVR system.
16. The user device, as claimed in claim 15, wherein the user device is configured for streaming the playlist to the user device by
checking if filename of a next entry in the playlist is same as filename of previous entry, on the user device detecting at least one other entry in the playlist; and
sending only byte range request to the DVR system, if filename of a next entry in the playlist is same as filename of previous entry by the user device.

Dated: 10th May 2013 Signature:
Vikram Pratap Singh Thakur (Patent Agent)
,TagSPECI:FORM 2
The Patent Act 1970
(39 of 1970)
&
The Patent Rules, 2005

COMPLETE SPECIFICATION
(SEE SECTION 10 AND RULE 13)

TITLE OF THE INVENTION

“A method and system for generating custom event based streams from a video recording system”
APPLICANTS:

Name : HCL Technologies Limited

Nationality : Indian

Address : HCL Technologies Ltd., 50-53 Greams
Road,Chennai – 600006, Tamil Nadu, India

The following specification particularly describes and ascertains the nature of this invention and the manner in which it is to be performed:-

FIELD OF INVENTION
[001] This invention relates to video monitoring systems and more particularly to event monitoring in video streams recorded by video monitoring systems.

BACKGROUND OF INVENTION
[002] Currently, video surveillance systems (hereinafter referred to as Digital Video Recorder (DVR) systems) have become widespread in use. Such systems may be found in public areas such as streets, parks and sensitive location or in private areas such as buildings where sensitive information/property may be present.
[003] The DVR systems may perform recording in a continuous manner and store the video stream in a suitable location, such as a memory located in a central location. However, this results in large amounts of data being generated, which in turn leads to problems with storing such large amounts of data. Also, it may not feasible to view the entire footage generated by the DVR systems to isolate a single event.
[004] To overcome this issue, DVR systems initiate recording only on a specified event being detected in the view of the video system have been used. However, such systems require modifications to existing equipment by installing video cameras and/or backend equipment which have this functionality enabled. This entails a further cost to the installer of the DVR systems.
OBJECT OF INVENTION
[005] The principal object of this invention is to propose a method and system to enable user(s) to remotely view event based video streams, even if there is only regular recordings happening on a recording system and no event based recordings.

STATEMENT OF INVENTION
[006] Accordingly the invention provides a a system for enabling a user to access at least one video from a Digital Video Recording (DVR) network, the system comprising of a DVR management module, at least one user device and a DVR system, wherein the DVR management module is configured for checking at least one event occurring in a video stream, on the user sending a request to the DVR management module and the request comprises of the at least one event; calculating a start time and a stop time for the at least one event in the video stream; obtaining at least one video clip from the video stream based on the start time and the stop time; creating a playlist, wherein the playlist comprises of at least one video clip related to at least one event; sending the playlist and associated information to the user device; and the user device configured for streaming the playlist, based on inputs from the user.
[007] There is also provided a method for enabling a user to access at least one video from a Digital Video Recording (DVR) network, the method comprising of checking at least one event occurring in a video stream by a DVR management module, on the user sending a request to the DVR management module and the request comprises of the at least one event; calculating a start time and a stop time for the at least one event in the video stream by the DVR management module; obtaining at least one video clip from the video stream by the DVR management module based on the start time and the stop time; creating a playlist by the DVR management module, wherein the playlist comprises of at least one video clip related to at least one event; sending the playlist and associated information by the DVR management module to a user device; and streaming the playlist to the user device, based on inputs from the user.
[008] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.
BRIEF DESCRIPTION OF FIGURES
[009] This invention is illustrated in the accompanying drawings, through out which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:
[0010] FIG. 1 depicts a Digital Video Recording (DVR) system connected to a user and a DVR management module, according to embodiments as disclosed herein;
[0011] FIG. 2 depicts a DVR management module, according to embodiments as disclosed herein;
[0012] FIG. 3 depicts a playlist structure, when the videos do not overlap, according to embodiments as disclosed herein;
[0013] FIG. 4 depicts a playlist structure, when the videos overlap, according to embodiments as disclosed herein;
[0014] FIG. 5 is a flowchart illustrating the process of recording events, according to embodiments as disclosed herein; and
[0015] FIGs. 6a, 6b, 6c and 6d are flowcharts illustrating the process of a user accessing video files related to specific events and viewing the video files as a playlist, according to embodiments as disclosed herein.

DETAILED DESCRIPTION OF INVENTION
[0016] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[0017] The embodiments herein propose a method and system to enable user(s) to remotely view event based video streams, even if there are only regular recordings happening on a recording system and no event based recordings. Referring now to the drawings, and more particularly to FIGS. 1 through 6, where similar reference characters denote corresponding features consistently throughout the figures, there are shown preferred embodiments.
[0018] FIG. 1 depicts a Digital Video Recording (DVR) system connected to a user and a DVR management module, according to embodiments as disclosed herein. The figure depicts a DVR system 102 connected to a DVR management module 101. The DVR management module 101 is connected to a user using a suitable means, such as the World Wide Web (WWW) and so on. The user may access the web server using a suitable device such as a computer, a laptop, a mobile device (such as a mobile phone, a tablet, a Personal Digital Assistant (PDA) and so on) or any other device which can enable the user to access the WWW. The user may use the user device to request for video files related to a specific event. The user device may also be used to configure options such as type of event, time duration of each file, camera identification, pre-record time for the event type, post-record time for the event type and so on. The user may view streams of video on the user device, wherein the streams may be based on a playlist.
[0019] The DVR system 102 comprises of at least one video camera and associated modules, such as a server to enable the user to access the recorded video, a storage means to store the video files and so on. The DVR system 102 records videos in a format suitable for streaming (such as HTTP (Hypertext Transfer Protocol), RTSP (Real Time Streaming Protocol) and so on) over an IP (Internet Protocol) based network, such as MP4 (MPEG (Moving Picture Experts Group -14), FLV (Flash Video) or another suitable file format. In an embodiment herein, the recorded video file may have a file header at the beginning of the file, as it is required for pseudo-streaming. The DVR system 102 comprises a means for enabling an external system (such as the DVR management module 101) for syncing time with the DVR system 102. The DVR system 102 may enable syncing using a suitable means such as an API (Application Programming Interface), NTP (Network Time Protocol) or any other equivalent means. The DVR system 102 is further enabled to return file name of a recorded file to the DVR management module 101 for a particular time stamp and file creation time and file duration, on receiving a request from the DVR management module 101. The DVR system 102 enables the user to download a portion of a recorded file, using a suitable means such as Byte-Range requests.
[0020] The DVR management module 101 is connected to a plurality of event generators. The event generator is configured for generating events. The event generator may be any sensor based system (e.g. Motion detection, light sensor, temperature sensor) which would generate events as per sensor configuration; a software generating events, or even manually generated events. In an embodiment herein, the event generator sends the event with event type. In another embodiment herein, the event generator generates events based on offline analysis of videos. The event could be sent over a physical port or over a network so that the DVR management module 101 may receive the events. The DVR management module 101 captures received events and saves the events along with type of event and time stamp for the same in a suitable location such as a database. The DVR management module 101 comprises a means to receive user inputs for viewing event based video streams. The DVR management module 101 will process those inputs to provide playlist files using which the user will stream event based videos.
[0021] On receiving a play list from the DVR management module 101, a customized client present on the user device with streaming capabilities reads and parses the playlist file as well as any associated information. The user device creates a timeline with marks representing events. The user device reads the first entry in the playlist and fetches file headers by sending a request (with Byte range headers) for file headers corresponding to that entry to the DVR system 102. Once the user device has received the file headers (with information to seek within the file), it would send a request for the video file with byte range corresponding to start time and stop time to the DVR system 102. The DVR system 102 responds with the video file corresponding to byte offset. The video file is streamed and played by the user device. Once file transfer corresponding to one event is completed, the user device reads the next event entry from the playlist. If the entry is having same filename, then the user device sends only byte–range request to be sent to the DVR system 102. If it’s a new filename, then the user device makes a second request for file download which would be sent to the DVR system 102 to fetch file headers, and the same process as disclosed above is repeated.
[0022] During streaming, when the user device would switch from one file to another file in the playlist, there may be a break in the playback. To overcome this break in the playback, the user device may do a parallel download of file headers and content of the next file in the playlist. So when the user device would switch from one file to another it would start playing video without a break. Also, the time of the start of the stream could land on a P-frame of the video file; in this case, the user device will traverse to the previous I-frame of the video and perform decoding from the previous I-frame of the video; however the user device will display content from the P-frame itself after decoding.
[0023] FIG. 2 depicts a DVR management module, according to embodiments as disclosed herein. The DVR management module 101 comprises of an event manager 201, an event recorder 202, a database 203 and an interface 204. The interface 204 enables the DVR management module 101 to interact with the event generators, the DVR system 101 and at least one user.
[0024] On receiving an event from the event generators via the interface, the event recorder 202 saves the events along with type of event and time stamp for the same in the database 203. The event recorder 202 may store the events in the database 203 using the following format:
DateTime: Date and time of event generated.
EventType: Type of event.
[0025] On receiving a request from the user with the time duration, the event manager 201 queries the database 203 and prepares a list containing at least one event that occurred in this duration, based on the information present in the database 203. Using this list, the event manager 201 creates a playlist file which will be used by the user device to view event based streams. The playlist file will be created in following format (as depicted in figure 3):
, ,
Wherein,
Filename is the File name of recorded video from a camera which will be streamed;
StartStreamTime is the time within the file from where stream should start; and
StopStreamTime is the time within the file where stream should end.
[0026] To generate the playlist file, the event manager 201 performs the following steps:
1. Calculate the start and stop time for a video stream as:
StartTime = EventTime – Configured Pre-record time for the event type.
StopTime = EventTime + Configured Post-record time for the event type.
2. Obtain the recorded file name for camera1 corresponding to StartTime and StopTime by using the interface 204 to query the DVR system 102.
3. If both queries return the same filename,
a. Calculate stream times as
StartStreamTime = StartTime – FileCreationTime
StopStreamTime = StopTime – FileCreationTime
b. Add an entry to playlist file as:
, ,
4. If both queries return different filenames,
a. Calculate stream times as
StartStreamTime = StartTime – File1CreationTime
StopStreamTime = StopTime – File2CreationTime
b. Add entries to playlist file as
, ,
, ,
5. Perform steps 1- 4 for each event in the event list.
[0027] The event manager 201 sends the playlist file along with associated information to the user. The associated information comprises event information such as event type, timestamp and so on.
[0028] If time stamp of two events is such that a portion of pre-post video for them overlaps, then the event manager 201 detects the overlap and ensures that only unique video content is streamed for the events (as depicted in FIG. 4).
[0029] In an embodiment herein, the DVR Management module 101 may reside in the cloud and this functionality can be provided as a service to end customers by a service provider.
[0030] FIG. 5 is a flowchart illustrating the process of recording events, according to embodiments as disclosed herein. The event generator generates (501) an event and sends (502) the generated event to the DVR management module 101. The event generator sends the event along with the event type. On receiving an event from the event generators, the DVR management module 101 saves (503) the events along with type of event and time stamp for the same in the database 203. The DVR management module 101 may store the events in the database 204 using the following format:
DateTime: Date and time of event generated.
EventType: Type of event.
The various actions in method 500 may be performed in the order presented, in a different order or simultaneously. Further, in some embodiments, some actions listed in FIG. 5 may be omitted.
[0031] FIGs. 6a, 6b, 6c and 6d are flowcharts illustrating the process of a user accessing video files related to specific events and viewing the video files as a playlist, according to embodiments as disclosed herein. The user requests (601) for video files related to at least one specific event using the user device. The user may also configure options such as type of event, time duration of each file, camera identification time, pre-record time for the event type, post-record time for the event type and so on. On receiving a request from the user, the DVR management module 101 queries (602) the database 204 and prepares (603) a list containing at least one event that occurred in this duration, based on the information present in the database 204. The DVR management module 101 calculates (604) the start and stop time for a video stream as:
StartTime = EventTime – Configured Pre-record time for the event type.
StopTime = EventTime + Configured Post-record time for the event type.
[0032] The DVR management module 101 further queries (605) the DVR system 102 for recorded file name for camera1 corresponding to StartTime and StopTime by using the interface 203 to query the DVR system 102. On receiving (606) the response from the DVR system, the DVR management module 101 checks (607) if both the received filenames are the same. If both queries return the same filename, then the DVR management module 101 calculates (608) stream times as
StartStreamTime = StartTime – FileCreationTime
StopStreamTime = StopTime – FileCreationTime
[0033] And adds (609) an entry to the playlist file as:
, ,
[0034] If both queries return different file names, the DVR management module 101 calculates (610) stream times as
StartStreamTime = StartTime – File1CreationTime
StopStreamTime = StopTime – File2CreationTime
[0035] And adds (611) entries to the playlist file as
, ,
, ,
[0036] The DVR management module 101 further checks (612) if there are any events in the event list to be processed. If there is at least one event to be processed, the DVR management module 101 repeats steps 604 – 611 for each event. The DVR management module 101 creates (613) a playlist file which will be used by the user device to view event based streams. The DVR management module 101 sends (614) the playlist file along with associated information (such as event info list) to the user. On receiving a play list from the DVR management module 101, a customized client present on the user device with streaming capabilities reads and parses (615) the playlist file as well as any associated information (such as event info list). The user device creates (616) a timeline based on the event info list with marks representing events. The user device reads (617) the first entry in the playlist and sends (618) a request (with Byte range headers) for file headers corresponding to that entry to the DVR system 102. The DVR system 102, on receiving the request, sends (619) the requested file headers to the user device. Once the user device has received the file headers (with information to seek within the file), the user device sends (620) a request for the video file with byte range corresponding to start time and stop time to the DVR system 102. The DVR system 102 responds (621) with file contents corresponding to byte offset. The user device streams and plays (622) the video file. Once file transfer corresponding to one event is completed, the user device checks (623) if there are other entries present in the playlist. If there are event entries present, the user device reads (624) the next event entry from the playlist. If the entry is having (625) same filename, then the user device sends (626) only byte–range request to be sent to the DVR system 102. If it’s a new filename, then the user device repeats steps 618 onwards. The various actions in method 600 may be performed in the order presented, in a different order or simultaneously. Further, in some embodiments, some actions listed in FIGs. 6a, 6b, 6c and 6d may be omitted.
[0037] In an embodiment herein, if the user wants to view event videos from two cameras, the user sends this information in the initial request along with event type and time duration to the DVR management module 101. The DVR management module 101 creates two playlists for each camera. The DVR management module 101 returns two playlists and an event list to the user side. The user device uses two instances of the client, one each for displaying streams from each camera.
[0038] Embodiments disclosed herein use existing video recordings to allow user on demand view of pre-post event based recordings without taking extra space for recordings and extra processing for event based recording. This system utilizes already existing recordings for providing event based recording view.
[0039] Embodiments disclosed herein enable users to view event based videos (both pre and post) for any kind of events whether internal to a DVR system or from some external sources. The external event sources can be video analytics software which can detect events in the video file and generate an event.
[0040] Embodiments disclosed herein support any number of event generators, as there is no limit on number of event generators and type of events.
[0041] Embodiments disclosed herein have removed the need to have separate recordings for different event based recordings. Same recorded video could be used for viewing event based video for any type of event. This enables saving resources in terms of space and processing power.
[0042] Embodiments disclosed herein use streaming over the WWW and hence viewing of event based video is available at remote locations.
[0043] Since embodiments disclosed herein act upon previously recorded files, there is no limit of any memory buffer size on pre-record duration or post-record duration.
[0044] The embodiments disclosed herein can be implemented through at least one software program running on at least one hardware device and performing network management functions to control the network elements. The network elements shown in Figs. 1 and 2 include blocks which can be at least one of a hardware device, or a combination of hardware device and software module.
[0045] The embodiment disclosed herein describes a method and system to enable user(s) to remotely view event based video streams, even if there is only regular recordings happening on a recording system and no event based recordings. Therefore, it is understood that the scope of the protection is extended to such a program and in addition to a computer readable means having a message therein, such computer readable storage means contain program code means for implementation of one or more steps of the method, when the program runs on a server or mobile device or any suitable programmable device. The method is implemented in a preferred embodiment through or together with a software program written in e.g. Very high speed integrated circuit Hardware Description Language (VHDL) another programming language, or implemented by one or more VHDL or several software modules being executed on at least one hardware device. The hardware device can be any kind of portable device that can be programmed. The device may also include means which could be e.g. hardware means like e.g. an ASIC, or a combination of hardware and software means, e.g. an ASIC and an FPGA, or at least one microprocessor and at least one memory with software modules located therein. The method embodiments described herein could be implemented partly in hardware and partly in software. Alternatively, the invention may be implemented on different hardware devices, e.g. using a plurality of CPUs.
[0046] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.