METHOD AND APPARATUS FOR HIGHLY SCALABLE INTRAFRAME VIDEO CODING

• US 20090175333A1
• Filed: 01/09/2008
• Published: 07/09/2009
• Est. Priority Date: 01/09/2008
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: HSIANG, SHIH-TA
• Granted Patent: US 8,126,054 B2
• Time in Patent Office: Days
• US Class Current: 375/240.120
• CPC Class Codes: H04N 19/33 in the spatial domain
• 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 19/63 using sub-band based transform, e.g. wavelets
• CPC Class Codes: H04N 19/635 characterised by filter definition or implementation details

Abstract

An apparatus and method is provided for highly scalable intraframe video coding. The conventional macroblock DCT tools are integrated with the subband filter banks for the improved efficiency of scalable compression. The enhancement layers are represented in a subband domain and coded by an inter-layer frame texture coder utilizing inter-layer prediction signal formed by the decoded previous layer. Each quality enhancement layer is additionally scalable in resolution.

Claims

1. A quality scalable video encoding method for compressing a source video frame, comprising:

generating a base quality layer bitstream by encoding the source video frame at a specified lowest quality level or encoding bitrate;

generating a set of enhancement layer bitstreams by encoding the source video frame at a set of the increasing quality levels or encoding bitrates, the encoding including;

decomposing the source video frame by subband analysis filter banks into a subband representation of the source video frame;

forming an inter-layer prediction signal which is a representation of a recovered video frame of the next lower quality layer; and

generating the enhancement layer bitstream by encoding the subband representation by an inter-layer frame texture encoder that further utilizes the inter-layer prediction signal to remove inter-layer redundancy; and

composing a scalable bitstream from the base quality layer bitstream and the set of enhancement layer bitstreams using a bitstream multiplexer.

2. The method according to claim 1, wherein the inter-layer frame texture encoder comprises a block transform encoder.

3. The method according to claim 2, wherein the subband representation is sequentially partitioned into a plurality of block subband representations for non-overlapped blocks, further comprising encoding the block subband representation for each non-overlapped block by the inter-layer frame texture encoder and encoding the block subband representation further comprises:

forming a spatial prediction signal from recovered neighboring subband coefficients;

selecting a prediction signal between the inter-layer prediction signal and the spatial prediction signal for each block adaptively; and

encoding, by the transform block encoder, a prediction error signal that is a difference of the block subband representation and the selected prediction signal for each block.

4. The method according to claim 3, wherein the inter-layer frame texture encoder comprises an enhancement-layer intraframe encoder conforming to the scalable video coding extension to the MPEG-4 Part 10 AVC/H.264 standard but without a clipping operation performed on the decoded signal.

5. The method according to claim 1, wherein the inter-layer frame texture encoder comprises an intra-layer frame texture encoder that encodes a residual signal that is a difference between the subband representation and the inter-layer prediction signal.

6. The method according to claim 1, wherein the enhancement-layer bitstreams contain a syntax element indicating the number of the decomposition levels of each enhancement layer.

7. The method according to claim 1, wherein the base quality layer further comprises one or more than one scalable layers for representing the source video frame at the reduced or same resolution.

8. The method according to claim 7, wherein the first scalable layer of the base quality layer is compatible with one of the standards MPEG-1, MPEG-2, MPEG-4, and H.264/AVC.

9. The method according to claim 3, wherein blocks of the subband coefficients are further grouped according to a slice group map, as defined in H.264/AVC, that further conforms to the subband partition or resolution scale of the subband representation and different groups of coefficient blocks are encoded into different bitstream packets.

10. A quality scalable video decoding method for decompressing a coded video frame into a decoded video frame, comprising:

extracting the packets containing the related coded coefficients to a requested resolution and/or quality level from a scalable bitstream using a bitstream parser;

recovering a base quality version of the decoded video frame from the extracted packets of the base quality layer bitstream;

recovering a set of decoded subband representations of increasing quality level, wherein each decoded subband representation in the set is recovered by decoding the extracted packets of the corresponding one of the set of enhancement layer bitstreams, comprising for each enhancement layer bitstream

forming an inter-layer prediction signal which is a representation of a recovered video frame of the next lower quality layer, and

recovering the subband representation by decoding the extracted packets of the corresponding enhancement layer by an inter-layer frame texture decoder that further utilizes the inter-layer prediction signal to remove inter-layer redundancy;

synthesizing the decoded video frame from the decoded subband representation at the final enhancement layer using subband synthesis filter banks; and

performing a clipping operation on the synthesized video frame according to the pixel value range.

11. The method according to claim 10, wherein the inter-layer frame texture decoder comprises a block transform decoder.

12. The method according to claim 11, wherein the decoded subband representation is sequentially partitioned into a plurality of decoded block subbands for non-overlapped blocks, further comprising generating the decoded block subband representation for each non-overlapped block by the inter-layer frame texture decoder and generating the decoded block subband representation further comprises:

forming a spatial prediction signal from recovered neighboring subband coefficients;

selecting a prediction signal between the inter-layer prediction signal and the spatial prediction signal for each block adaptively; and

decoding, by the transform block decoder, a prediction error signal that is a difference of the decoded block subband representation and the selected prediction signal for each block.

13. The method according to claim 12, wherein the set of enhancement layer bitstreams is compatible with the scalable video coding extension to the MPEG-4 Part 10 AVC/H.264 standard.

14. The method according to claim 12, wherein the inter-layer frame texture decoder comprises an enhancement layer intra-frame decoder described in one of the standards MPEG-4 Part 10 AVC/H.264, MPEG-2, MPEG-4, and the version.2 of H.263 but without a clipping operation performed on the decoded signal in the intra-frame decoder.

15. The method according to claim 12, wherein the method further comprises a bitstream parser that generates an output bitstream by removing the packets of high frequency subbands unrelated to the requested resolution for decoded video from the input scalable bitstream comprising packets for representing coded subband coefficients grouped according to a sliced group map, as defined in H.264/AVC, that further conforms to the subband partition or resolution scale of the subband representation.

16. A bitstream parser that accepts a scalable bitstream as input and generates an output bitstream by removing the packets of high frequency subbands unrelated to the requested resolution for decoded video, wherein the input scalable bitstream includes packets for representing coded subband coefficients grouped according to a sliced group map, as defined in H.264/AVC, that further conforms to the subband partition or resolution scale of the subband representation.

17. A quality scalable encoding system for compressing a source video frame, comprising:

a base quality layer encoder for generating a base quality layer bitstream by encoding the source video frame at a specified lowest quality level or encoding bitrate;

an enhancement layer encoder for generating a set of enhancement layer bitstreams at a set of the increasing quality level or encoding bitrate, the enhancement layer encoder comprising

subband analysis filter banks for decomposing the source video frame by subband analysis filter banks into a subband representation of the source video frame, and

an inter-layer frame texture encoder for generating the enhancement layer bitstream by encoding the subband representation utilizing an inter-layer prediction signal, the inter-layer frame texture encoder further comprising an inter-layer predictor for forming the inter-layer prediction signal which is a representation of a recovered video frame of the next lower quality layer; and

a bitstream multiplexer for composing a scalable bitstream from the base quality layer bitstream and enhancement layer bitstreams.

18. The system according to claim 17, wherein the inter-layer frame texture encoder comprises a block transform encoder.

19. An quality scalable decoding system for decompressing a coded video frame from a scalable bitstream, comprising:

a bitstream parser for extracting packets related to a requested resolution and/or quality level from a scalable bit stream using a bitstream parser

a base layer decoder for decoding a base quality version of the extracted packets of the base quality layer bitstream;

an enhancement layer decoder for recovering a set of decoded subband representations of increasing quality level, wherein each decoded subband representation in the set is recovered by decoding the extracted packets of the corresponding one of the set of enhancement layer bitstreams, the enhancement layer decoder comprising an inter-layer frame texture decoder for decoding a subband representation utilizing an inter-layer prediction signal, the inter-layer frame texture decoder further comprising an inter-layer predictor for forming an inter-layer prediction signal which is a representation of a recovered video frame of the next lower quality layer;

synthesis filter banks for synthesizing the decoded frame from the decoded subband representation at the final enhancement layer; and

a delimiter that performs a clipping operation on the synthesized video frame according to the pixel value range

20. The system according to claim 19, wherein the inter-layer frame texture decoder comprises a block transform decoder.