Method for communicating audiovisual programs over a communications network

• US 5,874,986 A
• Filed: 06/26/1996
• Issued: 02/23/1999
• Est. Priority Date: 06/26/1996
• Status: Expired due to Term

• Current Assignee: AT&T Corporation (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Simon, Steven David, Gibbon, David Crawford, Shahraray, Behzad, Markowitz, Robert Edward
• Primary Examiner(s): Chin, Tommy P.
• Assistant Examiner(s): Philippe, Gims S.
• Application Number:
  US08/670,924
• Time in Patent Office: 972 Days
• Field of Search: 348/13, 348/719, 348/10, 348/7, 348/12, 348/460, 340/825.31, 364/514 R, 364/514, 370/62, 370/335, 395/157, 395/600, 385/341, 455/4.2
• US Class Current: 725/134
• CPC Class Codes: H04N 21/23406 involving management of server-side video buffer
• CPC Class Codes: H04N 21/234381 by altering the temporal resolution, e.g. decreasing the frame rate by frame skipping
• CPC Class Codes: H04N 21/2368 Multiplexing of audio and video streams
• CPC Class Codes: H04N 21/4312 involving specific graphical features, e.g. screen layout, special fonts or colors, blinking icons, highlights or animations
• CPC Class Codes: H04N 21/4314 for fitting data in a restricted space on the screen, e.g. EPG data in a rectangular grid
• CPC Class Codes: H04N 21/4341 Demultiplexing of audio and video streams
• CPC Class Codes: H04N 21/44004 involving video buffer management, e.g. video decoder buffer or video display buffer
• CPC Class Codes: H04N 21/44209 Monitoring of downstream path of the transmission network originating from a server, e.g. bandwidth variations of a wireless network arrangements for maintenance or administration in data switching networks involving bandwidth and capacity management H04L41/0896
• CPC Class Codes: H04N 21/4622 Retrieving content or additional data from different sources, e.g. from a broadcast channel and the Internet web site content organization and management for information retrieval from the Internet G06F16/958; transmission by internet of broadcast information H04H60/82; stock exchange data over packet-switching network H04L12/1804; push services including data channel over packet-switching network H04L12/1859
• CPC Class Codes: H04N 21/4782 Web browsing , e.g. WebTV
• CPC Class Codes: H04N 21/4884 for displaying subtitles
• CPC Class Codes: H04N 21/643 Communication protocols network streaming protocols, e.g. real-time transport protocol [RTP] or real-time control protocol [RTCP], H04L65/65
• CPC Class Codes: H04N 21/6543 for forcing some client operations, e.g. recording remote booting in general G06F9/4416
• CPC Class Codes: H04N 21/812 involving advertisement data advertising per se G06Q30/02
• CPC Class Codes: H04N 21/8586 by using a URL processing chained hypermedia data for information retrieval G06F16/94; information retrieval from the Internet by using URLs G06F16/955; URL in broadcast information H04H20/93; Web-based protocols H04L67/02
• CPC Class Codes: H04N 7/173 with two-way working, e.g. subscriber sending a programme selection signal

Abstract

Audiovisual programs are transmitted over a low-bandwidth network in a compressed form in which the number of video frames has been reduced by selecting "significant" frames. The user sees a series of still images accompanying an apparently full audio channel. The frames are downloaded to the user in an order designed to assure, first, that the next few frames necessary for viewing are present, but also so that the user can scroll throughout the program even as it is being downloaded. This is accomplished by first downloading the full audio for the program portion requested by the user'"'"'s viewer software, and then downloading the video frames based on requests from the viewer software, which has access to a table indicating which video frames are associated with which audio portions. The software uses the table to download frames needed immediately, as well as to download advance frames based on their significance.

Claims

1. A method for receiving an audiovisual program at a station of a communications network and playing back said program at said station, said audiovisual program having content comprising a video data stream, said video data stream being transmitted in a compressed format in which frames determined to have greater significance than other frames are retained and frames determined to have lesser significance than other frames are discarded, said program further being accompanied by a table indicating which frames are present in said compressed program and a time offset at which display of each frame is to begin, said method comprising the steps of:

establishing a pre-fetch interval;

requesting, at said station, transmission by said network of data to fill a pre-fetch queue having a duration commensurate with said pre-fetch interval;

when said pre-fetch queue is full, requesting, at said station, transmission by said network of additional data from later portions of said program.

2. The method of claim 1 wherein said step of requesting additional data comprises:

examining said table; and

selecting, for request, data referenced in said table as a function of which portion of said program said data originate in.

3. The method of claim 2 wherein said selecting step comprises:

analyzing at least one of

(a) performance of said communications network, and

(b) availability of data previously requested from different portions of said program; and

choosing data, for request, based on said analysis.

4. The method of claim 1 further comprising the steps of:

playing back contents of said pre-fetch queue; and

as said contents of said pre-fetch queue are played back, requesting, at said station, transmission by said network of data to maintain said pre-fetch queue.

5. The method of claim 4 further comprising accepting, at substantially any time, user input for selecting playback of one of said later portions of said program.

6. The method of claim 1 wherein said audiovisual program comprises at least one other data stream.

7. The method of claim 6 wherein said at least one other data stream comprises audio data.

8. The method of claim 6 wherein said at least one other data stream comprises closed-captioning data.

9. A method of communicating audiovisual programs over a communications network, and playing back said programs at a station of said network, said method comprising the steps of:

analyzing content of said audiovisual program;

compressing said audiovisual program as a function of said content to create a compressed program;

compiling a table indicating which portions of said program are present in said compressed program and transmitting said table over said network in association with said compressed program;

examining said table at said station; and

selecting at said station, for request from said network, data referenced in said table as a function of which portion of said program said data originates in.

10. The method of claim 9 wherein:

said audiovisual program comprises audio data and video data; and

said compressing step comprises compressing said video data and transmitting said audio data in a substantially real-time stream.

11. The method of claim 10 wherein said compressing step comprises compressing said video data by analyzing significance of frames, retaining frames expected to have greater significance than other frames, and discarding frames expected to have lesser significance than other frames.

12. The method of claim 11 wherein said step of analyzing significance of frames comprises examining frames for one of (a) a scene change relative to adjacent frames, (b) a fade, and (c) a change in volume level of audio associated with said frame relative to audio associated with adjacent frames.

13. The method of claim 11 further comprising:

compiling a table indicating which frames are present in said compressed program and a time offset at which display of each frame is to begin; and

transmitting said table as part of said compressed program.

14. The method of claim 13 further comprising compressing said table prior to said transmitting step.

15. The method of claim 14 wherein said table compressing step comprises transmitting portions of said table at different times.

16. The method of claim 9 further comprising transmitting a second visual program along with said audiovisual program.

17. The method of claim 16 wherein said transmitting step comprises:

compiling a table indicating which frames are present in said second visual program and a time offset at which display of each frame is to begin; and

transmitting said table as part of said second visual program.

18. The method of claim 9 wherein said selecting step comprises, at said station:

establishing a pre-fetch interval;

requesting, at said station, transmission by said network of data to fill a pre-fetch queue having a duration substantially equal to said pre-fetch interval;

when said pre-fetch queue is full, requesting, at said station, transmission by said network of additional data from later portions of said program.

19. The method of claim 18 wherein said step of requesting additional data comprises:

examining said table; and

selecting, for request, data referenced in said table as a function of which portion of said program said data originate in.

20. The method of claim 19 wherein said selecting step comprises:

analyzing at least one of

(a) performance of said communications network, and

(b) availability of data previously requested from different portions of said program; and

choosing data, for request, based on said analysis.