Local picture identifier and computation of co-located information

• US 8,189,666 B2
• Filed: 02/02/2009
• Issued: 05/29/2012
• Est. Priority Date: 02/02/2009
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Wu, Yongjun, Thumpudi, Naveen, Gan, Kim-chyan
• Primary Examiner(s): SIMITOSKI, MICHAEL J
• Application Number:
  US12/364,325
• Publication Number:
  US 20100195721A1
• Time in Patent Office: 1,212 Days
• Field of Search: 375/240.12
• US Class Current: 375/240.12
• CPC Class Codes: H04N 19/102 characterised by the element, parameter or selection affected or controlled by the adaptive coding
• CPC Class Codes: H04N 19/159 Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• 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 19/46 Embedding additional information in the video signal during the compression process H04N19/517, H04N19/68, H04N19/70 take precedence
• CPC Class Codes: H04N 19/513 Processing of motion vectors
• 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

Abstract

Video decoding innovations for using local picture identifiers and computing co-located information are described. In one aspect, a decoder identifies reference pictures in a reference picture list of a temporal direct prediction mode macroblock that match reference pictures used by a co-located macroblock using local picture identifiers. In another aspect, a decoder determines whether reference pictures used by blocks are the same by comparing local picture identifiers during calculation of boundary strength. In yet another aspect, a decoder determines a picture type of a picture and based on the picture type selectively skips or simplifies computation of co-located information for use in reconstructing direct prediction mode macroblocks outside the picture.

Claims

1. A computer-implemented method for transforming encoded video information using a video decoder, the method comprising:

receiving encoded video information in a bitstream; and

during decoding the encoded video information, wherein the decoding uses plural reference pictures identified with local picture identifiers;

identifying a temporal direct prediction mode macroblock, wherein the temporal direct prediction mode macroblock is associated with a reference picture list of one or more of the plural reference pictures;

identifying a co-located macroblock of the temporal direct prediction mode macroblock, wherein the co-located macroblock uses one or more reference pictures of the plural reference pictures;

identifying one or more reference pictures in the reference picture list that match the one or more reference pictures used by the co-located macroblock, wherein the identifying the one or more reference pictures in the reference picture list uses local picture identifiers; and

using the identified one or more reference pictures in reconstruction of the temporal direct prediction mode macroblock;

wherein the local picture identifiers are assigned to picture structures when allocated, and wherein the decoder reuses the local picture identifiers during the decoding based on availability of the local picture identifiers.

2. The method of claim 1 wherein the local picture identifiers are 8-bit local picture identifiers, and wherein the decoder sets the local picture identifiers independent of picture order count.

3. The method of claim 1 wherein the local picture identifiers are 5-bit local picture identifiers.

4. The method of claim 1 wherein the local picture identifiers are greater than or equal to 5-bits, and less than or equal to 32-bits, and wherein the decoder selectively reuses the local picture identifiers during decoding based on which of the local picture identifiers are in use, thereby controlling bit depth of the local picture identifiers and speeding up the identification of the one or more reference pictures in the reference picture list.

5. The method of claim 1 wherein the temporal direct prediction mode macroblock is in a B slice of the bitstream, and wherein the reference picture list is associated with the B slice.

6. The method of claim 1 further comprising, during decoding the encoded video information:

creating a table, wherein the table stores reference picture list index values of the reference picture list, and wherein the stored reference picture list index values are indexed in the table by the local picture identifiers;

wherein the identifying the one or more reference pictures in the reference picture list is performed by looking up one or more local picture identifiers of the one or more reference pictures used by the co-located macroblock in the table and retrieving one or more corresponding reference picture list index values, wherein the retrieved reference picture list index values identify the one or more reference pictures in the reference picture list that match the one or more reference pictures used by the co-located macroblock.

7. The method of claim 1 wherein the local picture identifiers are 8-bit local picture identifiers, and wherein an invalid picture identifier is assigned an 8-bit value of 255.

8. A computing device implementing a video decoder, the computing device comprising:

a processing unit; and

memory;

wherein the computing device is configured to perform operations for decoding video, the operations comprising;

receiving encoded video information in a bitstream; and

during decoding the encoded video information, wherein the decoding uses plural reference pictures identified with local picture identifiers;

identifying a temporal direct prediction mode macroblock, wherein the temporal direct prediction mode macroblock is associated with a reference picture list of one or more of the plural reference pictures;

identifying a co-located macroblock of the temporal direct prediction mode macroblock, wherein the co-located macroblock uses one or more reference pictures of the plural reference pictures;

identifying one or more reference pictures in the reference picture list that match the one or more reference pictures used by the co-located macroblock, wherein the identifying the one or more reference pictures in the reference picture list uses local picture identifiers; and

using the identified one or more reference pictures in reconstruction of the temporal direct prediction mode macroblock;

wherein the local picture identifiers are assigned to picture structures when allocated, and wherein the decoder reuses the local picture identifiers during the decoding based on availability of the local picture identifiers.

9. The computing device of claim 8 wherein the local picture identifiers are 8-bit local picture identifiers, and wherein the decoder sets the local picture identifiers independent of picture order count.

10. The computing device of claim 8 wherein the local picture identifiers are 5-bit local picture identifiers.

11. The computing device of claim 8 wherein the local picture identifiers are greater than or equal to 5-bits, and less than or equal to 32-bits, and wherein the decoder selectively reuses the local picture identifiers during decoding based on which of the local picture identifiers are in use, thereby controlling bit depth of the local picture identifiers and speeding up the identification of the one or more reference pictures in the reference picture list.

12. The computing device of claim 8 wherein the temporal direct prediction mode macroblock is in a B slice of the bitstream, and wherein the reference picture list is associated with the B slice.

13. The computing device of claim 8, the operations further comprising, during decoding the encoded video information:

creating a table, wherein the table stores reference picture list index values of the reference picture list, and wherein the stored reference picture list index values are indexed in the table by the local picture identifiers;

wherein the identifying the one or more reference pictures in the reference picture list is performed by looking up one or more local picture identifiers of the one or more reference pictures used by the co-located macroblock in the table and retrieving one or more corresponding reference picture list index values, wherein the retrieved reference picture list index values identify the one or more reference pictures in the reference picture list that match the one or more reference pictures used by the co-located macroblock.

14. The computing device of claim 8 wherein the local picture identifiers are 8-bit local picture identifiers, and wherein an invalid picture identifier is assigned an 8-bit value of 255.

15. A computer-readable storage medium storing computer-executable instructions for causing a computer system programmed thereby to perform the method for decoding encoded video information, the method comprising:

receiving encoded video information in a bitstream; and

during decoding the encoded video information, wherein the decoding uses plural reference pictures identified with local picture identifiers;

identifying a temporal direct prediction mode macroblock, wherein the temporal direct prediction mode macroblock is associated with a reference picture list of one or more of the plural reference pictures;

identifying a co-located macroblock of the temporal direct prediction mode macroblock, wherein the co-located macroblock uses one or more reference pictures of the plural reference pictures;

identifying one or more reference pictures in the reference picture list that match the one or more reference pictures used by the co-located macroblock, wherein the identifying the one or more reference pictures in the reference picture list uses local picture identifiers; and

using the identified one or more reference pictures in reconstruction of the temporal direct prediction mode macroblock;

wherein the local picture identifiers are greater than or equal to 5-bits, and less than or equal to 32-bits, and wherein the decoder selectively reuses the local picture identifiers during decoding based on which of the local picture identifiers are in use, thereby controlling bit depth of the local picture identifiers and speeding up the identification of the one or more reference pictures in the reference picture list.

16. The computer-readable storage medium of claim 15 wherein the local picture identifiers are 8-bit local picture identifiers, and wherein the decoder sets the local picture identifiers independent of picture order count.

17. The computer-readable storage medium of claim 15 wherein the local picture identifiers are 5-bit local picture identifiers.