Method and apparatus for conveying compressed video data over a noisy communication channel

• US 5,289,276 A
• Filed: 06/19/1992
• Issued: 02/22/1994
• Est. Priority Date: 06/19/1992
• Status: Expired due to Term

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Siracusa, Robert J., Zdepski, Joel W.
• Primary Examiner(s): Powell, Mark R.
• Assistant Examiner(s): Metjahic, Safet
• Application Number:
  US07/901,045
• Time in Patent Office: 613 Days
• Field of Search: 358/141, 358/167, 358/133, 358/135, 358/136, 358/12, 358/13, 375/58, 371/69.1, 370/99, 370/110.1
• US Class Current: 348/469
• CPC Class Codes: H04N 19/00 Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
• CPC Class Codes: H04N 19/39 involving multiple description coding [MDC], i.e. with separate layers being structured as independently decodable descriptions of input picture data
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/70 characterised by syntax aspects related to video coding, e.g. related to compression standards
• CPC Class Codes: H04N 19/89 involving methods or arrangements for detection of transmission errors at the decoder
• CPC Class Codes: H04N 21/236 Assembling of a multiplex stream, e.g. transport stream, by combining a video stream with other content or additional data, e.g. inserting a URL [Uniform Resource Locator] into a video stream, multiplexing software data into a video stream; Remultiplexing of multiplex streams; Insertion of stuffing bits into the multiplex stream, e.g. to obtain a constant bit-rate; Assembling of a packetised elementary stream multiplexing of data packets for data networks, e.g. RTP/UDP H04L65/00
• CPC Class Codes: H04N 21/434 Disassembling of a multiplex stream, e.g. demultiplexing audio and video streams, extraction of additional data from a video stream; Remultiplexing of multiplex streams; Extraction or processing of SI; Disassembling of packetised elementary stream demultiplexing of data packets for data networks, e.g. RTP/UDP H04L65/00

Abstract

A digital compressed video signal transmission system includes a transport processor for segmenting compressed data into transport cells for transmission. Particular portions of the compressed data are formatted into further transport cells, which further transport cells are interspersed with normally occurring transport cells. The further transport cells include redundant video signal data which may be utilized to resynchronize a compressed video signal decoder after loss or corruption of transmitted data.

Claims

1. In a digital video transmission system for transmitting a hierarchically layered compressed video signal wherein respective layers of compressed signal include headers containing data descriptive of said respective layers, apparatus for segmenting said hierarchically layered compressed video signal into transport cells, respective transport cells containing a first predetermined number, N, of data bits divided between a transport cell header including a second predetermined number, K, of data bits and an information packet of N-K data bits, said transport cell headers data bits containing information for identifying data bits of corresponding information packets, said apparatus comprising:

a source of hierarchically layered compressed video signal (HLCVS);

means responsive to header data of said HLCVS for generating, at least in part, said transport cell headers;

means responsive to said HLCVS for dividing said HLCVS, including headers, into information packets of no greater than N-K data bits;

means responsive to header data of said HLCVS for generating redundant information packets of no greater than N-K data bits including only predetermined types of header data of said HLCVS;

means for concatenating transport cell headers and corresponding information packets to form transport cells; and

means for interspersing transport cells including information packets of HLCVS data with transport cells including redundant information packets to form a sequence wherein a first number of redundant information packets included in first video frames is greater than a second number (including zero) of redundant information packets in second video frames.

2. In a digital video transmission system for transmitting a hierarchically layered compressed video signal wherein respective layers of compressed signal include headers containing data descriptive of said respective layers, apparatus for segmenting said hierarchically layered compressed video signal into transport cells, respective transport cells containing a first predetermined number, N, of data bits divided between a transport cell header including a second predetermined number, K, of data bits and an information packet of N-K data bits, said transport cell headers data bits containing information for identifying data bits of corresponding information packets, said apparatus comprising:

a source of hierarchically layered compressed video signal (HLCVS);

means responsive to header data of said HLCVS for generating, at least in part, said transport cell headers;

means responsive to said HLCVS for dividing said HLCVS, including headers, into information packets of no greater than N-K data bits;

means responsive to header data of said HLCVS for generating redundant information packets of no greater than N-K data bits including only predetermined types of header data of said HLCVS;

means for concatenating transport cell headers and corresponding information packets to form transport cells and redundant transport cells; and

means for interspersing transport cells with redundant transport cells, and for cyclically reducing the frequency of occurrence of redundant transport cells interspersed between transport cells.

3. In a digital video transmission system for transmitting a hierarchically layered compressed video signal wherein respective layers of compressed signal include headers containing data descriptive of said respective layers, apparatus for segmenting said hierarchically layered compressed video signal into transport cells, respective transport cells containing a first predetermined number, N, of data bits divided between a transport cell header including a second predetermined number, K, of data bits and an information packet of N-K data bits, said transport cell headers data bits containing information for identifying data bits of corresponding information packets, said apparatus comprising:

a source of hierarchically layered compressed video signal (HLCVS) which conforms to MPEG standards;

means responsive to header data of said HLCVS for generating, at least in part, said transport cell headers;

means responsive to said HLCVS for dividing said HLCVS, including headers, into information packets of no greater than N-K data bits;

means responsive to header data of said HLCVS for generating redundant information packets of no greater than N-K data bits including only redundant information packets of sequence header data, and redundant information packets of group of pictures (GOP) header and redundant information packets of picture (PICT) header data;

means for concatenating transport cell headers and corresponding information packets to form transport cells and redundant transport cells; and

means for interspersing transport cells with redundant transport cells.

4. The apparatus set forth in claim 3 wherein said means for interspersing repeats in succession, a predetermined number of transport cells including redundant information packets of sequence header data.

5. The apparatus set forth in claim 4 wherein said means for interspersing includes means for cyclically reducing the frequency of transport cells (including redundant information packets) interspersed between transport cells including information packets of HLCVS data.

6. The apparatus set forth in claim 3 wherein said HLCVS includes frames, I, of video data compressed according to intraframe compression techniques, and frames (P, B) of video data compressed according to interframe compression techniques, and said means for interspersing transport cells intersperses transport cells including redundant information packets of sequence header data and redundant information packets of GOP and PICT header data with transport cells having information packets of MPEG (I) frame data;

and intersperses transport cells including redundant information packets of only GOP/PICT header data with transport cells having information packets of MPEG (B, P) frame data.

7. The apparatus set forth in claim 3 wherein said means for generating redundant information packets includes:

memory means for storing header data occurring in said HLCVS; and

said means for generating, generates redundant information packets from header data stored in said memory means, and appends thereto, if said header data occupies less than N-K data bits, currently occurring HLCVS data to a total of N-K data bits.

8. In a digital video transmission system for transmitting a hierarchically layered compressed video signal wherein respective layers of compressed signal include headers containing data descriptive of said respective layers, apparatus for segmenting said hierarchically layered compressed video signal into transport cells, respective transport cells containing a first predetermined number, N, of data bits divided between a transport cell header including a second predetermined number, K, of data bits and an information packet of N-K data bits, said transport cell headers data bits containing information for identifying data bits of corresponding information packets, said apparatus comprising:

means for segmenting said compressed video signal into fixed length packets and forming respective packets into transport cells; and

generating redundant packets with predetermined portions of only headers of said compressed video signal and forming respective redundant packets into further transport cells, and interspersing said further transport cells with said transport cells such that said further cells occur with declining frequency according to a predetermined pattern.

9. In a digital video transmission system for transmitting a hierarchically layered compressed video signal said compressed video signal being compressed on a field/frame basis according to at least two types of compression coding intraframe and interframe and wherein respective layers of compressed signal include headers containing data descriptive of said respective layers, apparatus for segmenting said hierarchically layered compressed video signal into transport cells, respective transport cells containing a first predetermined number, N, of data bits divided between a transport cell header including a second predetermined number, K, of data bits and an information packet of N-K data bits, said transport cell headers data bits containing information for identifying data bits of corresponding information packets, said apparatus comprising:

means for segmenting said compressed video signal into fixed length packets and forming respective packets into transport cells; and

generating redundant packets with predetermined portions of headers of said compressed video signal and forming respective redundant packets into further transport cells, and interspersing said further transport cells with said transport cells with declining frequency and such that said further transport cells are interspersed with said transport cells of intraframe compressed video signal differently than said further transport cells are interspersed with said transport cells of interframe compressed video signal.

10. In a digital video transmission system for transmitting in transport cells, hierarchically layered compressed video signal including video header data related to video frames, said transport cells being interspersed with further transport cells including redundant data corresponding to predetermined portions of said video header data, said transport and further transport cells including transport cell headers and information packets, receiver apparatus comprising:

means for receiving transmitted said transport cells and said further transport cells, and separating said transport cell headers and information packets;

means responsive to transport cell header data for determining the occurrence of transport cells which include said video header data being lost or corrupted during transmission, and responsive to determining such occurrence, discarding subsequently occurring non-corrupted transport cells until the occurrence of one of said further transport cells, and

decompression means responsive to said information packets for generating decompressed video signal.

11. The receiver set forth in claim 10 further including means for substituting data from said further transport cells for data in said transport cells on the occurrence of lost or corrupted transport cells.

12. The receiver set forth in claim 10 further including means for discarding said redundant data in said further transport cells if no determination is made that transport cells preceding said further transport cells have been lost or corrupted.

13. The receiver set forth in claim 10 wherein said transport cell headers include indicia indicating whether corresponding transmitted transport cells include compressed video signal or said redundant data, and said receiver includes means responsive to said indicia for determining whether respective transport cells include compressed video signal or redundant data.

14. In a digital video transmission system for transmitting a hierarchically layered compressed video signal, said compressed video signal including frames of compressed video data compressed by intraframe processing and frames of compressed video data compressed by interframe processing, and wherein respective layers of compressed signal include video headers descriptive of said respective layers, apparatus for segmenting said compressed video signal into transport cells, respective transport cells containing a transport cell header and a payload packet containing a portion of said compressed video signal, said apparatus comprising:

a source of hierarchically layered compressed video signal (HLCVS);

means responsive to said HLCVS for dividing said HLCVS, into payload packets;

means responsive to said HLCVS for generating redundant payload packets including predetermined types of said hierarchically layered compressed video signal;

means, responsive to header data of said HLCVS, for generating, at least in part, said transport cell headers, respective cell headers including a data field which indicates whether a transport payload is compressed video signal or a redundant payload packet;

means for concatenating transport cell headers and corresponding payload or redundant payload packets to form transport cells; and

means for interspersing transport cells including payload packets with transport cells including redundant payload packets, said means interspersing a greater number of transport cells containing redundant payload packets with frames of compressed video data compressed by intraframe processing than frames of compressed video data compressed by interframe processing.

15. In a digital video transmission system for transmitting a hierarchically layered compressed video signal, said compressed video signal occuring in groups of frames, and wherein respective layers of compressed signal include video headers descriptive of said respective layers, apparatus for segmenting said compressed video signal into transport cells, respective transport cells containing a transport cell header and a payload packet containing a portion of said compressed video signal, said apparatus comprising:

a source of hierarchically layered compressed video signal (HLCVS);

means responsive to said HLCVS for dividing said HLCVS, into payload packets;

means responsive to said HLCVS for generating redundant payload packets including predetermined types of said hierarchically layered compressed video signal;

means, responsive to header data of said HLCVS, for generating, at least in part, said transport cell headers, respective cell headers including a data field which indicates whether a transport payload is compressed video signal or a redundant payload packet;

means for concatenating transport cell headers and corresponding payload or redundant payload packets to form transport cells; and

means for interspersing transport cells including payload packets with transport cells including redundant payload packets, said means interspersing a greater number of transport cells containing redundant payload packets with transport cells containing payload packets near the beginning of a group of frames than near the end of a group of frames.