Method and an apparatus for mixing compressed video

• US 20030123537A1
• Filed: 12/04/2002
• Published: 07/03/2003
• Est. Priority Date: 12/04/2001
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Polycom Incorporated (Plantronics, Inc.)
• Inventors: Elbaz, Moshe, Yona, Ilan
• Granted Patent: US 7,245,660 B2
• Time in Patent Office: Days
• US Class Current: 375/240.01
• CPC Class Codes: H04N 19/107 between spatial and temporal predictive coding, e.g. picture refresh
• CPC Class Codes: H04N 19/174 the region being a slice, e.g. a line of blocks or a group of blocks
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/40 using video transcoding, i.e. partial or full decoding of a coded input stream followed by re-encoding of the decoded output stream
• CPC Class Codes: H04N 19/59 involving spatial sub-sampling or interpolation, e.g. alteration of picture size or resolution
• 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 7/152 Multipoint control units therefor

Abstract

A system for controlling a conference that takes input streams from a variety of sources, at least some of the streams having a relatively low-resolution, and composes the input streams into a single output stream of a relatively high-resolution. In doing the conversion the system takes intra Macro Blocks (MBs) of the input stream and produces inter output frames. As part of the conversion process, the system converts the Groups Of Blocks (GOBs) that have GOB headers into slices.

Claims

1. A method for use in composing a plurality of compressed video input streams, at least one input stream having a first resolution, into a single output stream in another resolution that is higher than the first resolution, the method comprising:

converting an input intra frame into an inter frame.

2. The method of claim 1, wherein at least one of the plurality of compressed video input streams has been compressed according to a compression standard selected from a group consisting of H.263 and MPEG 4.

3. The method of claim 1, wherein the first resolution includes at least one type of resolution selected from a group consisting of QCIF, CIF and 4CIF.

4. The method of claim 1, wherein the other resolution includes at least one type of resolution selected from a group consisting of CIF, 4CIF and 16CIF.

5. The method of claim 1 further comprising:

responding to a video update request from a receiver by transmitting an intra background frame.

6. The method of claim 1 further comprising:

converting at least one of the plurality of compressed video input streams into H.263 Annex K compression standard.

7. The method of claim 1 wherein the composing further comprises converting Groups Of Block (GOB) headers in the compressed video input streams into slice headers in the single output stream.

8. A method comprising:

composing a plurality of compressed video input streams, each stream having an input resolution, into a single output stream of an output resolution that is higher than the input resolution of the compressed video input streams, by at least

converting the plurality of compressed video input streams into high-resolution H.263 with Annex K compression standard, if the compressed video input stream is not already in a format based on the H.263 with Annex K standard;

converting Groups Of Blocks (GOBs) headers in the compressed video input streams into slice headers, if the compressed video input stream is not already in a format based on the H.263 with Annex K standard;

converting an intra frame into an inter frame; and

responding to a video update request from a receiver by transmitting an intra background frame.

9. A system comprising:

at least one parser being operative to

receive a compressed video input stream having an input resolution and being divided into Groups Of Blocks (GOBs) or slices; and

deliver a converted compressed video stream, which is a compressed video stream that has been converted into one that is divided into slices of a higher resolution than the compressed video input stream.

10. The system of claim 9, the parser also being operative to convert an intra frame associated with at least one of the one or more compressed video input streams to an output that represents an inter frame associated with the converted compressed video stream.

11. The system of claim 9, wherein the system is operative to compose a single compressed output stream from data associated with at least the converted compressed video stream, the system further comprising a packetizer operative to packetize the single compressed output stream.

12. The system of claim 9, wherein the parser is also operative to generate a recommended division point list that is associated with the one or more compressed video input streams.

13. The system of claim 9 wherein the compressed video input stream has been compressed according to a compression standard selected from a group consisting of H.263 and MPEG4.

14. The system of claim 9 wherein the one or more compressed video input streams includes frames of at least one type selected from a group consisting of QCIF, CIF and 4CIF.

15. The system of claim 9 wherein the single compressed video output stream includes frames of at least one type selected from a group consisting of CIF, 4CIF and 16CIF.

16. The system of claim 9, also being operative to convert the one or more compressed video input streams into a H.263 Annex K converted compressed video stream.

17. The system of claim 9, also being operative to convert the GOBs'"'"' headers in the one or more compressed video input streams into slice headers in the converted compressed video stream.

18. The system of claim 9, further comprising at least one packetizer, which is operative to respond to a video update request by transmitting an artificial intra background frame.

19. The system of claim 18, wherein the packatizer is operative to compose a single output stream from data associated with the one or more compressed video input streams.

20. The system of claim 19 wherein the packetizer is also operative to divide the output stream into packets based on a recommended division point list associated with the one or more compressed video input streams.

21. A system comprising:

at least one packetizer, each packetizer is operative to

respond to a video update request by transmitting an artificial intra background frame.

22. The system of claim 21 further comprising:

at least one parser, each parser being operative to

receive a compressed video input stream having an input resolution and being divided into Groups Of Blocks (GOBs) or slices;

convert the compressed video input stream into a higher resolution compressed video stream according to H.263 Annex K;

convert an intra frame associated with the compressed video input streams into an output frame that represents an inter frame;

generate a recommended division points list that is associated with the compressed video input stream; and

deliver a converted compressed video stream, which is a compressed video stream that has been converted into one that is divided into slices and has the second resolution.

23. The system of claim 22 wherein:

each packetizer is further operative to

compose the compressed video output stream and

divide the output stream into packets based on the recommended division points list associated with the compressed video input stream; and

the system is operative to packetize the single compressed video output stream while parsing the one or more compressed video input streams.

24. A system comprising:

a plurality of conference modules, each conference module including

(I) a shared memory having buffers;

(II) a plurality of input modules associated with a plurality of input streams, a plurality of parsers, a plurality of depacketizers, and a plurality of linked lists, each of the input modules having at least

(A) one of the plurality of depacketizers that depacketizes one of the plurality of input streams of a first resolution, which is divided into Groups Of Blocks (GOBs) or slices from a network,

(B) one of the plurality of parser that

(1) converts the GOBs'"'"' headers into slice headers,

(2) converts intra frames of the first resolution into inter frames of a second resolution that is higher than the first resolution,

(3) generates recommended division points,

(4) delivers a converted stream in portions to the buffers, where the converted stream is a compressed video stream of the second resolution having the inter frames of the second resolution and the slice headers, and

(5) generates at least one of the plurality of linked lists, each linked list being a list of pointers pointing to where corresponding ones of the portions are stored in the buffers;

(III) a plurality of output modules for processing the buffers designated in the plurality of linked lists, the plurality of input streams being associated with the buffers and each of a group of the plurality of output modules composing at least part of the plurality of input streams into one output stream of the second resolution, each output module having at least

(A) a background buffer for storing information associated with empty screen parts of the output stream, and

(B) a packetizer for dividing the output stream into packets and sending the packets via the network to endpoints; and

(IV) a conference manager that

(A) communicates with a host regarding how to layout a conference, and

(B) assigns the group of input modules to the output module.