PICTURE CODING SUPPORTING BLOCK MERGING AND SKIP MODE

• US 20130279577A1
• Filed: 05/02/2013
• Published: 10/24/2013
• Est. Priority Date: 11/04/2010
• Status: Active Grant

• Current Assignee: GE Video Compression, LLC (General Electric Company)
• Original Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Inventors: SCHWARZ, Heiko, KIRCHHOFFER, Heiner, HELLE, Philipp, BROSS, Benjamin, MARPE, Detlev, WIEGAND, Thomas, OUDIN, Simon, STEGEMANN, Jan
• Granted Patent: US 9,924,193 B2
• Time in Patent Office: Days
• US Class Current: 375/240.12
• CPC Class Codes: H04N 19/103 Selection of coding mode or of prediction mode
• CPC Class Codes: H04N 19/13 Adaptive entropy coding, e.g. adaptive variable length coding [AVLC] or context adaptive binary arithmetic coding [CABAC]
• CPC Class Codes: H04N 19/159 Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
• CPC Class Codes: H04N 19/172 the region being a picture, frame or field
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/184 the unit being bits, e.g. of the compressed video stream
• CPC Class Codes: H04N 19/50 using predictive coding H04N19/61 takes precedence
• CPC Class Codes: H04N 19/52 by predictive encoding
• CPC Class Codes: H04N 19/70 characterised by syntax aspects related to video coding, e.g. related to compression standards

Abstract

A coding efficiency increase is achieved by using a common signalization within the bitstream with regard to activation of merging and activation of the skip mode. One possible state of one or more syntax elements within the bitstream may signalize for a current sample set of a picture that the sample set is to be merged and has no prediction residual encoded and inserted into the bitstream. A common flag may signalize whether the coding parameters associated with a current sample set are to be set according to a merge candidate or to be retrieved from the bitstream, and whether the current sample set of the picture is to be reconstructed based on a prediction signal depending on the coding parameters associated with the current sample set, without any residual data, or to be reconstructed by refining the prediction signal depending on the coding parameters associated with the current sample set by means of residual data within the bitstream.

Claims

1. An apparatus configured to decode a bitstream into which a picture is coded, the sample array of the picture being partitioned into sample sets each of which is associated with respective coding parameters, the apparatus being configured to be, for a current sample set, commonly responsive to a flag within the bitstream as to a first decision as to whether the coding parameters associated with the current sample set are to be set according to a merge candidate or to be retrieved from the bitstream, and a second decision as to whether the current sample set of the picture is to be reconstructed merely based on a prediction signal depending on the coding parameters associated with the current sample set, without any residual data, or to be reconstructed by refining the prediction signal depending on the coding parameters associated with the current sample set by means of residual data within the bitstream,

such that the apparatus

if the flag within the bitstream signals that the coding parameters associated with the current sample set are to be set according to a merge candidate,

acquires the coding parameters associated with the current sample set by setting same according to a merge candidate, and reconstructs the current sample set of the picture merely based on a prediction signal depending on the coding parameters without any residual data.

2. The apparatus according to claim 1 wherein the decoder is configured such that the apparatus

if the flag within the bitstream does not signal that the coding parameters associated with the current sample set are to be set according to a merge candidate,

is responsive to another flag within the bitstream such that the apparatus, depending on the other flag,

acquires the coding parameters associated with the current sample set by setting same according to a merge candidate, acquires residual data for the current sample set from the bitstream and reconstructs the current sample set of the picture based on the prediction signal and the residual data, or

extracts the coding parameters associated with the current sample set from the bitstream, acquires residual data for the current sample set from the bitstream and reconstructs the current sample set of the picture based on the prediction signal and the residual data.

3. The apparatus according to claim 1 wherein the decoder is configured such that the apparatus

if the flag within the bitstream signals that the coding parameters associated with the current sample set are to be set according to a merge candidate,

applies a predetermined one among supported partitioning patterns for the current current sample set, and

if the flag within the bitstream does not signal that the coding parameters associated with the current sample set are to be set according to a merge candidate,

is responsive to partitioning information within the bitstream signaling one of the supported partitioning patterns for the current sample set.

4. The apparatus according to claim 3, wherein the predetermined one among the supported partitioning patterns is a non-partitioning mode and the decoder is configured such that the apparatus

if the flag within the bitstream signals that the coding parameters associated with the current sample set are to be set according to a merge candidate,

acquires coding parameters associated with the current sample set by setting same according to a merge candidate, and reconstructs the current sample set of the picture merely based on a prediction signal depending on the coding parameters without any residual data, and

if the flag within the bitstream does not signal that the coding parameters associated with the current sample set are to be set according to a merge candidate,

is responsive to partitioning information within the bitstream signaling one of the supported partitioning patterns for the current sample set,

acquires residual data for the current sample set from the bitstream,

for each sample subset of the signaled supported partitioning pattern of the current sample set, is responsive to another flag within the bitstream such that the decoder, depending on the other flag,

acquires coding parameters associated with the respective sample subset by setting same according to a merge candidate, or

extracts the coding parameters associated with the respective sample subset from the bitstream;

and

reconstructs the current sample set of the picture based on a prediction signal depending on the coding parameters of each sample subset and the residual data.

5. The apparatus according to claim 4, wherein the apparatus is configured to

if the signaled supported partitioning patterns specifies a subdivision of the current sample set into two or more sample subsets,

remove

for all sample subsets except a first sample subset of the sample subsets in a coding order,

from a set of merge candidates for the respective sample subset,

merge candidates comprising coding parameters which are the same as coding parameters associated with any of the sample subsets, which would, when being merged with the respective sample subset result in one of the supported partitioning patterns.

6. An apparatus for decoding a bitstream comprising a picture encoded therein, comprising

a subdivider configured to subdivide the picture into sample sets of samples;

a merger configured to merge the sample sets into groups of one or more sample sets each;

a decoder configured to decode the picture using coding parameters varying across the picture in units of the groups of sample sets, wherein the decoder is configured to decode the picture by predicting the picture, decoding a prediction residual for predetermined sample sets and combining the prediction residual and a prediction resulting from predicting the picture, for the predetermined sample sets;

an extractor configured to extract the prediction residual and the coding parameters from the bitstream, along with one or more syntax elements for each of at least a subset of the sample sets, signaling as to whether the respective sample set is to be merged into one of the groups along with another sample set or not, wherein the merger is configured to perform the merging responsive to the one or more syntax elements,

wherein one of the possible states of the one or more syntax elements signalizes that the respective sample set is to be merged into one of the groups along with another sample set and has no prediction residual encoded and inserted into the bitstream.

7. The apparatus according to claim 6, wherein the extractor is also configured to extract subdivision information from the bitstream, and the subdivider is configured to subdivide the picture into sample sets responsive to the subdivision information.

8. The apparatus according to claim 6, wherein the extractor and the merger are configured to sequentially step through the sample sets according to a sample set scan order, and to, for a current sample set,

extract a first binary syntax element from the bitstream;

if the first binary syntax element assumes a first binary state, merge the current sample set into one of the groups by inferring the coding parameters for the current sample set to be equal to the coding parameter associated with this group, skip the extraction of the prediction residual for the current sample set and step to the next sample set in sample set scan order;

if the first binary syntax element assumes a second binary state, extract a second syntax element from the bitstream; and

depending on the second syntax element, merge the current sample set into one of the groups by inferring the coding parameters for the current sample set to be equal to the coding parameters associated with this group or perform the extraction of the coding parameters for the current sample set, with extracting at least one further syntax element concerning the prediction residual for the current sample set.

9. The apparatus according to claim 6, wherein the one or more syntax elements for each of at least a subset of the sample sets also signals with which of a set of predetermined candidate sample sets neighboring the respective sample set, the respective sample set is to be merged, if the respective sample set is to be merged into any one of the disjoint sets along with another sample set.

10. The apparatus according to claim 6, wherein the extractor is also configured to extract subdivision information from the bitstream, and the subdivider is configured to hierarchically subdivide the picture into sample sets responsive to the subdivision information, and the extractor is configured to sequentially step through child sample sets of a parent sample set, comprised by the sample sets into which the picture is sub-divided, and, for a current child sample set,

extract a first binary syntax element from the bitstream;

if the first binary syntax element assumes a first binary state, merge the current child sample set into one of the disjoint sets by inferring the coding parameters for the current child sample set to be equal to the coding parameters associated with this disjoint set, skip the extraction of the prediction residual for the current child sample set and step to the next child sample sets;

if the first binary syntax element assumes a second binary state, extract a second syntax element from the bitstream; and

depending on the second syntax element, merge the current child sample set into one of the groups by inferring the coding parameters for the current child sample set to be equal to the coding parameters associated with this group or perform the extraction of the coding parameters for the current child sample set, with extracting at least one further syntax element concerning the prediction residual for the current child sample set, and then stepping to the next child sample sets,

with, for the next child sample sets, skipping extraction of the first binary syntax element if the first binary syntax element of the current child sample set assumes the first binary state and starting with extracting the second syntax element instead, and extracting the first binary syntax element if the first binary syntax element of the current child sample set assumes the second binary state.

11. The apparatus according to claim 10, wherein the first and second binary syntax elements are coded using context-adaptive variable length coding or context- adaptive (binary) arithmetic coding and the contexts for coding the syntax elements are derived based on the values for these syntax elements in already coded blocks.

12. An apparatus for encoding a picture into a bitstream, the sample array of the picture being partitioned into sample sets each of which is associated with respective coding parameters, the apparatus being configured to encode, for a current sample set, a flag into the bitstream commonly signaling as to whether the coding parameters associated with the current sample set are to be set according to a merge candidate or to be retrieved from the bitstream, and as to whether the current sample set of the picture is to be reconstructed merely based on a prediction signal depending on the coding parameters associated with the current sample set, without any residual data, or to be reconstructed by refining the prediction signal depending on the coding parameters associated with the current sample set by means of residual data within the bitstream,

such that the apparatus

if the flag within the bitstream signals that the coding parameters associated with the current sample set are to be set according to a merge candidate,

the coding parameters associated with the current sample set are to be set according to a merge candidate, and the current sample set of the picture is to be reconstructed merely based on a prediction signal depending on the coding parameters without any residual data.

13. An apparatus for encoding a picture comprising a subdivider configured to subdivide the picture into sample sets of samples;

a merger configured to merge the sample sets into groups of one or more sample sets each;

an encoder configured to encode the picture using coding parameters varying across the picture in units of the groups of sample sets, wherein the encoder is configured to encode the picture by predicting the picture and encoding a prediction residual for predetermined sample sets;

a stream generator configured to insert the prediction residual and the coding parameters into a bitstream, along with one or more syntax elements for each of at least a subset of the sample sets, signaling as to whether the respective sample set is merged into one of the groups along with another sample set or not,

wherein one of the possible states of the one or more syntax elements signalizes that the respective sample set is to be merged into one of the groups along with another sample set and has no prediction residual encoded and inserted into the bitstream.

14. A method for decoding a bitstream into which a picture is coded, the sample array of the picture being partitioned into sample sets each of which is associated with respective coding parameters, the method comprising, for a current sample set, commonly reacting to a flag within the bitstream as to a first decision as to whether the coding parameters associated with the current sample set are to be set according to a merge candidate or to be retrieved from the bitstream, and a second decision as to whether the current sample set of the picture is to be reconstructed merely based on a prediction signal depending on the coding parameters associated with the current sample set, without any residual data, or to be reconstructed by refining the prediction signal depending on the coding parameters associated with the current sample set by means of residual data within the bitstream,

such that

if the flag within the bitstream signals that the coding parameters associated with the current sample set are to be set according to a merge candidate, the coding parameters associated with the current sample set are acquired by setting same according to a merge candidate, and the current sample set of the picture are reconstructed merely based on a prediction signal depending on the coding parameters without any residual data.

15. A method for decoding a bitstream comprising a picture encoded therein, the method comprising

subdividing the picture into sample sets of samples;

merging the sample sets into groups of one or more sample sets each;

decoding the picture using coding parameters varying across the picture in units of the groups of sample sets, wherein the decoder is configured to decode the picture by predicting the picture, decoding a prediction residual for predetermined sample sets and combining the prediction residual and a prediction resulting from predicting the picture, for the predetermined sample sets;

extracting the prediction residual and the coding parameters from the bitstream, along with one or more syntax elements for each of at least a subset of the sample sets, signaling as to whether the respective sample set is to be merged into one of the groups along with another sample set or not, wherein the merger is configured to perform the merging responsive to the one or more yntax elements,

wherein one of the possible states of the one or more syntax elements signalizes that the respective sample set is to be merged into one of the groups along with another sample set and has no prediction residual encoded and inserted into the bitstream.

16. A method for encoding a picture into a bitstream, the sample array of the picture being partitioned into sample sets each of which is associated with respective coding parameters, the method comprising encoding, for a current sample set, a flag into the bitstream commonly signaling as to whether the coding parameters associated with the current sample set are to be set according to a merge candidate or to be retrieved from the bitstream, and as to whether the current sample set of the picture is to be reconstructed merely based on a prediction signal depending on the coding parameters associated with the current sample set, without any residual data, or to be reconstructed by refining the prediction signal depending on the coding parameters associated with the current sample set by means of residual data within the bitstream,

such that

if the flag within the bitstream signals that the coding parameters associated with the current sample set are to be set according to a merge candidate,

the coding parameters associated with the current sample set are to be set according to a merge candidate, and the current sample set of the picture is to be reconstructed merely based on a prediction signal depending on the coding parameters without any residual data.

17. A method for encoding a picture comprising

subdividing the picture into sample sets of samples;

merging the sample sets into groups of one or more sample sets each;

encoding the picture using coding parameters varying across the picture in units of the groups of sample sets, wherein the encoder is configured to encode the picture by predicting the picture and encoding a prediction residual for predetermined sample sets;

inserting the prediction residual and the coding parameters into a bitstream, along with one or more syntax elements for each of at least a subset of the sample sets, signaling as to whether the respective sample set is merged into one of the groups along with another sample set or not,

wherein one of the possible states of the one or more syntax elements signalizes that the respective sample set is to be merged into one of the groups along with another sample set and has no prediction residual encoded and inserted into the bitstream.

18. A computer program comprising a program code for performing, when running on a computer, a method for decoding a bitstream into which a picture is coded, the sample array of the picture being partitioned into sample sets each of which is associated with respective coding parameters, the method comprising, for a current sample set, commonly reacting to a flag within the bitstream as to a first decision as to whether the coding parameters associated with the current sample set are to be set according to a merge candidate or to be retrieved from the bitstream, and a second decision as to whether the current sample set of the picture is to be reconstructed merely based on a prediction signal depending on the coding parameters associated with the current sample set, without any residual data, or to be reconstructed by refining the prediction signal depending on the coding parameters associated with the current sample set by means of residual data within the bitstream, such that if the flag within the bitstream signals that the coding parameters associated with the current sample set are to be set according to a merge candidate, the coding parameters associated with the current sample set are acquired by setting same according to a merge candidate, and the current sample set of the picture are reconstructed merely based on a prediction signal depending on the coding parameters without any residual data.

19. A computer program comprising a program code for performing, when running on a computer, a method for encoding a picture comprising:

subdividing the picture into sample sets of samples;

merging the sample sets into groups of one or more sample sets each;

encoding the picture using coding parameters varying across the picture in units of the groups of sample sets, wherein the encoder is configured to encode the picture by predicting the picture and encoding a prediction residual for predetermined sample sets;

inserting the prediction residual and the coding parameters into a bitstream, along with one or more syntax elements for each of at least a subset of the sample sets, signaling as to whether the respective sample set is merged into one of the groups along with another sample set or not, wherein one of the possible states of the one or more syntax elements signalizes that the respective sample set is to be merged into one of the groups along with another sample set and has no prediction residual encoded and inserted into the bitstream.