APPARATUSES AND METHODS FOR CABAC INITIALIZATION

• US 20150063449A1
• Filed: 08/27/2013
• Published: 03/05/2015
• Est. Priority Date: 08/27/2013
• Status: Active Grant

• Current Assignee: Integrated Device Technology Incorporated (Renesas Electronics Corporation)
• Original Assignee: Magnum Semiconductor Incorporated (Renesas Electronics Corporation)
• Inventors: Pearson, Eric C., Novotny, Pavel
• Granted Patent: US 10,264,261 B2
• Time in Patent Office: Days
• US Class Current: 375/240.05
• 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 19/147 according to rate distortion criteria rate-distortion as a criterion for motion estimation H04N19/567
• 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 19/194 involving only two passes
• CPC Class Codes: H04N 19/436 using parallelised computational arrangements
• CPC Class Codes: H04N 19/91 Entropy coding, e.g. variable length coding [VLC] or arithmetic coding

Abstract

Apparatuses and methods for initializing a CABAC state are disclosed herein. An example apparatus may include an encoder configured to receive a macroblock dependent on at least one unencoded macroblock. The encoder may further be configured to receive a plurality of CABAC states and initialize CABAC in accordance with one of the plurality of CABAC states to encode the macroblock prior to the at least one unencoded macroblock being encoded.

Claims

1. An apparatus, comprising:

an encoder configured to receive a macroblock dependent on at least one unencoded macroblock, the encoder further configured to receive a plurality of CABAC states and initialize CABAC in accordance with a CABAC state of the plurality of CABAC states to encode the macroblock prior to the at least one unencoded macroblock being encoded.

2. The apparatus of claim 1, wherein the encoder is configured to operate in accordance with the H.264 encoding standard, the HEVC coding standard, or a combination thereof

3. The apparatus of claim 1, wherein the encoder is configured to operate in real-time.

4. The apparatus of claim 1, wherein the CABAC state of the plurality of CABAC states comprises a best standard initialization, a CABAC state provided during a pre-encode operation, a CABAC state for a co-located macroblock, a CABAC state for a macroblock last encoded by a same processing unit, a CABAC state of a spatially closest encoded macroblock, a CABAC state based on one or more encoded macroblocks of the picture, or a combination thereof

5. The apparatus of claim 1, wherein the macroblock comprises the first macroblock of a macroblock row.

6. The apparatus of claim 1, wherein the encoder is configured to encode a respective row of the picture.

7. The apparatus of claim 6, wherein the encoder is configured to operate in accordance with a spatial offset arrangement.

8. The apparatus of claim 1, wherein the encoder is configured to receive the CABAC state responsive, at least in part, to encoding the last macroblock of a macroblock TOW.

9. The apparatus of claim 1, wherein the at least one encoder is configured to encode the macroblock in accordance with rate-distortion optimization encoding.

10. An encoder, comprising:

a forward encoding path configured to receive a macroblock of a picture and provide a plurality of quantized coefficients based, at least in part, on the macroblock; and

a bitstream encoder coupled to the forward encoding path and configured to receive the plurality of quantized coefficients, the bitstream encoder further configured to provide a rate for encoding the plurality of quantized coefficients in accordance with a CABAC state to the forward encoding path and to initialize CABAC in accordance with the CABAC state to encode the plurality of quantized coefficients,

wherein the macroblock is dependent on at least one unencoded macroblock.

11. The encoder of claim 10, wherein the bitstream encoder is further configured to provide a rate to the forward encoding path comprises the bitstream encoder further configured to receive a plurality of CABAC states and determine a CABAC state of the plurality of CABAC states associated with a lowest RD score for encoding the macroblock.

12. The encoder of claim 11, wherein the bitstream encoder includes a CABAC states block configured to store the plurality of CABAC states and comprising a direct memory access block configured to receive the plurality of CABAC states from a memory.

13. The encoder of claim 10, wherein the macroblock comprises a first macroblock of a macroblock row.

14. The encoder of claim 10, wherein the bitstream encoder comprises:

an entropy encoder configured to receive the plurality of quantized coefficients and encode the plurality of quantized coefficients to provide the encoded bitstream; and

a rate calculation block configured to receive the plurality of quantized coefficients and the CABAC state and determine the rate for encoding the macroblock based, at least in part, on the CABAC state, the rate calculation block further configured to update the CABAC state to provide an updated CABAC state.

15. A method, comprising:

receiving a plurality of CABAC states;

determining which of the plurality of CABAC states is associated with a lowest RD score for encoding a macroblock dependent on one or more unencoded macroblocks; and

initializing CABAC according to the CABAC state of the plurality of CABAC states associated with the lowest RD score to encode the macroblock.

16. The method of claim 15, wherein the macroblock is spatially dependent, temporally dependent, or a combination thereof, on the one or more unencoded macroblocks.

17. The method of claim 15, wherein the CABAC state of the plurality of CABAC states associated with the lowest RD score comprises a best standard initialization, a CABAC state provided during a pre-encode operation, a CABAC state for a co-located macroblock, a CABAC state for a macroblock last encoded by a same processing unit, a CABAC state of a spatially closest encoded macroblock, a CABAC state based on one or more encoded macroblocks the picture, or a combination thereof.

18. The method of claim 15, wherein determining which of the plurality of CABAC states is associated with a lowest RD score for encoding a macroblock comprises determining a respective rate for each of the plurality of CABAC states and selecting a rate associated with a lowest RD score.

19. The method of claim 15, wherein initializing CABAC comprises encoding the macroblock in accordance with the H.264 standard, the HEVC standard, or a combination thereof.

20. The method of claim 15, further comprising:

performing a pre-encode operation on the macroblock to provide the CABAC state.

21. The method of claim 20, wherein performing a pre-encode operation comprises frame encoding the macroblock, field encoding the macroblock, adaptive quantization encoding the macroblock, or a combination thereof.

22. A method, comprising:

encoding a first macroblock, with a first set of processing units, to provide at least one of a plurality of CABAC states;

storing the at least one of a plurality of CABAC states in a memory;

initializing CABAC in accordance with a CABAC state of the plurality of CABAC states, with a second set of processing units, to encode the first macroblock prior to encoding a second macroblock on which encoding of the first macroblock depends.

23. The method of claim 22, wherein encoding a first macroblock comprises frame encoding each macroblock, field encoding each macroblock, adaptive quantization encoding each macroblock, or a combination thereof.

24. The method of claim 22, wherein storing the at least one of a plurality of CABAC states in a memory is responsive, at least in part, to determining that a next macroblock to be encoded is dependent on an unencoded macroblock.

25. The method of claim 22, wherein initializing CABAC in accordance with a CABAC state of the plurality of CABAC states comprises encoding the first macroblock in accordance with rate-distortion optimization encoding.