System and method for providing error resilience, random access and rate control in scalable video communications

• US 8,693,538 B2
• Filed: 03/05/2007
• Issued: 04/08/2014
• Est. Priority Date: 03/03/2006
• Status: Active Grant

• Current Assignee: Vidyo Incorporated (Enghouse Systems Limited)
• Original Assignee: Vidyo Incorporated (Enghouse Systems Limited)
• Inventors: Eleftheriadis, Alexandros, Hong, Danny, Shapiro, Ofer, Wiegand, Thomas
• Primary Examiner(s): HOLDER, BRADLEY W
• Application Number:
  US11/682,263
• Publication Number:
  US 20070230566A1
• Time in Patent Office: 2,591 Days
• Field of Search: 375/240.12, 375/240, 375/240.01
• US Class Current: 375/240.12
• CPC Class Codes: H04N 19/29 involving scalability at the object level, e.g. video object layer [VOL]
• CPC Class Codes: H04N 19/30 using hierarchical techniques, e.g. scalability H04N19/63 takes precedence
• CPC Class Codes: H04N 19/31 in the temporal domain
• CPC Class Codes: H04N 19/33 in the spatial domain
• CPC Class Codes: H04N 19/36 Scalability techniques involving formatting the layers as a function of picture distortion after decoding, e.g. signal-to-noise [SNR] scalability
• CPC Class Codes: H04N 19/44 Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder
• CPC Class Codes: H04N 19/593 involving spatial prediction techniques
• CPC Class Codes: H04N 19/65 using error resilience
• CPC Class Codes: H04N 19/89 involving methods or arrangements for detection of transmission errors at the decoder
• CPC Class Codes: H04N 19/895 in combination with error concealment
• CPC Class Codes: H04N 7/15 Conference systems

Abstract

Systems and methods for error resilient transmission, rate control, and random access in video communication systems that use scalable video coding are provided. Error resilience is obtained by using information from low resolution layers to conceal or compensate loss of high resolution layer information. The same mechanism is used for rate control by selectively eliminating high resolution layer information from transmitted signals, which elimination can be compensated at the receiver using information from low resolution layers. Further, random access or switching between low and high resolutions is also achieved by using information from low resolution layers to compensate for high resolution spatial layer packets that may have not been received prior to the switching time.

Claims

1. A digital video decoding system, the system comprising:

a decoder (including a combination of hardware and software) configured to decode a received digital video signal, which is coded in a scalable video coding format supporting temporal scalability and at least one of spatial and quality scalability,

wherein the scalable video coding format for spatial scalability includes a base spatial and at least one spatial enhancement layer, for quality scalability includes a base quality layer and at least one quality enhancement layer, and for temporal scalability includes a base temporal layer and at least one temporal enhancement layer, wherein the base temporal layers and enhancement temporal layers are interlinked by a threaded picture prediction structure for at least one of the spatial or quality scalability layers,

wherein, for decoding a picture at a target spatial or quality layer higher than the corresponding base layer, the decoder is configured to use coded information from a spatial or quality layer of said picture lower than the target layer in the threaded prediction structure when a portion of the target layer'"'"'s coded information is lost or not available,

wherein the digital video decoding system is disposed in a receiving endpoint, the system further comprising;

a linking communication network;

a conferencing server linked to the receiving endpoint and at least one transmitting endpoint by at least one communication channel each over the communication network, and

at least one endpoint that transmits the coded digital video that is coded in the scalable video coding format,

wherein the conferencing server is configured to selectively eliminate portions of input video signals received from transmitting endpoints that correspond to layers higher than the base spatial or quality layer, prior to creating an output video signal that is forwarded to the receiving endpoint,

wherein the conferencing server linked to the receiving endpoint and at least one transmitting endpoint is one of;

a Transcoding Multipoint Control Unit using cascaded decoding and encoding;

a Switching Multipoint Control Unit by selecting which input to transmit as output;

a Scalable Video Communication Server using selective multiplexing; and

a Compositing Scalable Video Communication Server using selective multiplexing and bitstream-level compositing.

2. The system of claim 1 wherein an encoder (including a combination of hardware and software) of the at least one transmitting endpoint is configured to encode transmitted media as frames in a threaded coding structure having a number of different temporal levels, wherein a subset of the frames (“

R”

) is particularly selected for reliable transport and includes at least the frames of the lowest temporal layer in the threaded coding structure so that the decoder can decode at least a portion of received media based on a reliably received frame of the type R after packet loss or error and thereafter is synchronized with the encoder, and wherein the conferencing server selectively eliminates portions of the input video signals received from transmitting endpoints that correspond to layers higher than the base spatial or quality layer in non-R frames only, prior to creating the output video signal that is forwarded to the receiving endpoint.

3. The system of claim 1, wherein the conferencing server is further configured to control the transmission rate of the output video signal that is forwarded to the receiving endpoint so that the retained portions of the input video signals received from transmitting endpoints that correspond to layers higher than the base spatial or quality layer do not adversely affect the smoothness of an output bit rate.

4. The system of claim 1, wherein the selective elimination by the conferencing server is performed according to desired output bit rate requirements.

5. The system of claim 1, wherein the decoder is configured to display decoded output pictures at a desired spatial resolution that falls in between an immediately lower and an immediately higher spatial layer provided by the coded video signal.

6. The system of claim 1, wherein the decoder is further configured to operate a decoding loop of the immediately higher spatial layer at a desired spatial resolution by scaling all coded data of the immediately higher spatial layer to the desired spatial resolution, and wherein resultant drift is eliminated by using at least one of:

periodic intra pictures;

periodic use of intra base layer mode; and

full resolution decoding of at least the lowest temporal layer of the immediately higher spatial layer.

7. The system of claim 1, wherein the scalable video coding format includes at least one of:

periodic intra pictures,

periodic intra macroblocks, and

threaded picture prediction,

in order to avoid drift when the target layer'"'"'s coded information that is lost or is not available corresponds to the base temporal layer.

8. The system of claim 1, where the scalable video coding format is based on hybrid coding, the format comprising H.264, VC-1 or AVS standards, wherein the coded information from a spatial or quality layer lower than the target layer used by the decoder when some or all of the target layer'"'"'s coded information is lost or is not available comprises at least one of:

motion vector data, appropriately scaled for the target layer'"'"'s resolution;

coded prediction error difference, upsampled to the target layer'"'"'s resolution; and

intra data, upsampled to the target layer'"'"'s resolution,

and wherein the decoder is further configured to use the target layer'"'"'s decoded pictures as references in the decoding process in order to construct the decoded output pictures, rather than the lower layer decoded reference pictures.

9. The system of claim 1, wherein the decoder is further configured to operate at least one decoding loop for spatial or quality layers higher than the target spatial or quality layer for at least the base temporal layer, so that when the decoder switches target layers it can immediately display decoded pictures at the new target layer resolution.

10. A method for decoding a digital video signal,

the method comprising:

receiving the digital video signal at a decoder (including a combination of hardware and software);

the digital video signal being coded in a scalable video coding format supporting temporal scalability and at least one of spatial and quality scalability, wherein the scalable video coding format for spatial scalability includes a base spatial and at least one spatial enhancement layer, for quality scalability includes a base quality layer and at least one quality enhancement layer, and for temporal scalability includes a base temporal layer and at least one temporal enhancement layer, wherein the base temporal layers and enhancement temporal layers are interlinked by a threaded picture prediction structure for at least one of the spatial or quality scalability layers; and

decoding a picture at a target spatial or quality layer higher than the corresponding base layer using coded information from a spatial or quality layer of said picture lower than the target layer in the threaded prediction structure when a portion of the target layer'"'"'s coded information is lost or not available;

wherein the decoder is disposed in a receiving endpoint in a linking communication network,

wherein a conferencing server is linked to the receiving endpoint and at least one transmitting endpoint by at least one communication channel each over the communication network, and

wherein the at least one transmitting endpoint transmits the coded digital video that is coded in the scalable video coding format;

the method further comprising;

at the conferencing server, selectively eliminating portions of input video signals received from transmitting endpoints that correspond to layers higher than the base spatial or quality layer, prior to creating an output video signal that is forwarded to the receiving endpoint.

wherein the conferencing server linked to the receiving endpoint and at least one transmitting endpoint is one of;

a Transcoding Multipoint Control Unit using cascaded decoding and encoding;

a Switching Multipoint Control Unit by selecting which input to transmit as output;

a Scalable Video Communication Server using selective multiplexing; and

a Compositing Scalable Video Communication Server using selective multiplexing and bitstream-level compositing.

11. The method of claim 10, further comprising, at an encoder (including a combination of hardware and software) of the at least one transmitting endpoint, encoding transmitted media as frames in a threaded coding structure having a number of different temporal levels, wherein a subset of the frames (“

R”

) is particularly selected for reliable transport and includes at least the frames of the lowest temporal layer in the threaded coding structure so that the decoder can decode at least a portion of received media based on a reliably received frame of the type R after packet loss or error and thereafter is synchronized with the encoder, and wherein the conferencing server selectively eliminates portions of the input video signals received from transmitting endpoints that correspond to layers higher than the base spatial or quality layer in non-R frames only, prior to creating the output video signal that is forwarded to the receiving endpoint.

12. The method of claim 10, further comprising, at the conferencing server controlling the transmission rate of the output video signal that is forwarded to the receiving endpoint so that the retained portions of the input video signals received from transmitting endpoints that correspond to layers higher than the base spatial or quality layer do not adversely affect the smoothness of an output bit rate.

13. The method of claim 10, wherein the selective elimination by the conferencing server is performed according to desired output bit rate requirements.

14. The method of claim 10, further comprising, at the decoder, displaying decoded output pictures at a desired spatial resolution that falls in between an immediately lower and an immediately higher spatial layer provided by the coded video signal.

15. The method of claim 10, further comprising, at the decoder, operating a decoding loop of the immediately higher spatial layer at a desired spatial resolution by scaling all coded data of the immediately higher spatial layer to the desired spatial resolution, and wherein resultant drift is eliminated by using at least one of:

periodic intra pictures;

periodic use of intra base layer mode; and

full resolution decoding of at least the lowest temporal layer of the immediately higher spatial layer.

16. The method of claim 10, wherein the scalable video coding format includes at least one of:

periodic intra pictures,

periodic intra macroblocks, and

threaded picture prediction,

in order to avoid drift when the target layer'"'"'s coded information that is lost or is not available corresponds to the base temporal layer.

17. The method of claim 10, where the scalable video coding format is based on hybrid coding, the format comprising H.264, VC-1 or AVS standards, wherein the coded information from a spatial or quality layer lower than the target layer used by the decoder when some or all of the target layer'"'"'s coded information is lost or is not available comprises at least one of:

motion vector data, appropriately scaled for the target layer'"'"'s resolution;

coded prediction error difference, upsampled to the target layer'"'"'s resolution; and

intra data, upsampled to the target layer'"'"'s resolution,

the method further comprising, at the decoder using the target layer'"'"'s decoded pictures as references in the decoding process in order to construct decoded output pictures, rather that the lower layer decoded reference pictures.

18. The method of claim 10 further comprising, at the decoder operating at least one decoding loop for spatial or quality layers higher than the target spatial or quality layer for at least the base temporal layer, so that when the decoder switches target layers it can immediately display decoded pictures at the new target layer resolution.

19. A non-transitory computer readable medium comprising a set of executable instructions to direct a processor to decode a digital video signal, by:

receiving the digital video signal at a decoder (including a combination of hardware and software);

the digital video signal being coded in a scalable video coding format supporting temporal scalability and at least one of spatial and quality scalability, wherein the scalable video coding format for spatial scalability includes a base spatial and at least one spatial enhancement layer, for quality scalability includes a base quality layer and at least one quality enhancement layer, and for temporal scalability includes a base temporal layer and at least one temporal enhancement layer, wherein the base temporal layers and enhancement temporal layers are interlinked by a threaded picture prediction structure for at least one of the spatial or quality scalability layers; and

decoding a picture at a target spatial or quality layer higher than the corresponding base layer using coded information from a spatial or quality layer of said picture lower than the target layer in the threaded prediction structure when a portion of the target layer'"'"'s coded information is lost or not available;

wherein the decoder is disposed in a receiving endpoint in a linking communication network,

wherein a conferencing server is linked to the receiving endpoint and at least one transmitting endpoint by at least one communication channel each over the communication network, and

wherein the at least one transmitting endpoint transmits the coded digital video that is coded in the scalable video coding format;

at the conferencing server, selectively eliminating portions of input video signals received from transmitting endpoints that correspond to layers higher than the base spatial or quality layer, prior to creating an output video signal that is forwarded to the receiving endpoint.

wherein the conferencing server linked to the receiving endpoint and at least one transmitting endpoint is one of;

a Transcoding Multipoint Control Unit using cascaded decoding and encoding;

a Switching Multipoint Control Unit by selecting which input to transmit as output;

a Scalable Video Communication Server using selective multiplexing; and

a Compositing Scalable Video Communication Server using selective multiplexing and bitstream-level compositing.

20. The computer readable medium of claim 19, further comprising executable instructions to direct the processor to, at an encoder (including a combination of hardware and software) of the at least one transmitting endpoint, encode transmitted media as frames in a threaded coding structure having a number of different temporal levels, wherein a subset of the frames (“

R”

) is particularly selected for reliable transport and includes at least the frames of the lowest temporal layer in the threaded coding structure so that the decoder can decode at least a portion of received media based on a reliably received frame of the type R after packet loss or error and thereafter is synchronized with the encoder, and wherein the conferencing server selectively eliminates portions of the input video signals received from transmitting endpoints that correspond to layers higher than the base spatial or quality layer in non-R frames only, prior to creating the output video signal that is forwarded to the receiving endpoint.

21. The computer readable medium of claim 19, further comprising executable instructions to direct the processor to, at the conferencing server control the transmission rate of the output video signal that is forwarded to the receiving endpoint so that the retained portions of the input video signals received from transmitting endpoints that correspond to layers higher than the base spatial or quality layer do not adversely affect the smoothness of an output bit rate.

22. The computer readable medium of claim 19, wherein the selective elimination by the conferencing server is performed according to desired output bit rate requirements.

23. The computer readable medium of claim 19 further comprising executable instructions to direct the processor to, at the decoder, display decoded output pictures at a desired spatial resolution that falls in between an immediately lower and an immediately higher spatial layer provided by the coded video signal.

24. The computer readable medium of claim 19 further comprising executable instructions to direct the processor to, at the decoder, operate a decoding loop of the immediately higher spatial layer at a desired spatial resolution by scaling all coded data of the immediately higher spatial layer to the desired spatial resolution, and wherein resultant drift is eliminated by using at least one of:

periodic intra pictures;

periodic use of intra base layer mode; and

full resolution decoding of at least the lowest temporal layer of the immediately higher spatial layer.

25. The computer readable medium of claim 19, wherein the scalable video coding format includes at least one of:

periodic intra pictures,

periodic intra macroblocks, and

threaded picture prediction,

in order to avoid drift when the target layer'"'"'s coded information that is lost or is not available corresponds to the base temporal layer.

26. The computer readable medium of claim 19, where the scalable video coding format is based on hybrid coding, the format comprising H.264, VC-1 or AVS standards, wherein the coded information from a spatial or quality layer lower than the target layer used by the decoder when some or all of the target layer'"'"'s coded information is lost or is not available comprises at least one of:

motion vector data, appropriately scaled for the target layer'"'"'s resolution;

coded prediction error difference, upsampled to the target layer'"'"'s resolution; and

intra data, upsampled to the target layer'"'"'s resolution,

further comprising executable instructions to direct the processor to, at the decoder, use the target layer'"'"'s decoded pictures as references in the decoding process in order to construct decoded output pictures, rather that the lower layer decoded reference pictures.

27. The computer readable medium of claim 19 further comprising executable instructions to direct the processor to, at the decoder, operate at least one decoding loop for spatial or quality layers higher than the target spatial or quality layer for at least the base temporal layer, so that when the decoder switches target layers it can immediately display decoded pictures at the new target layer resolution.