Method and apparatus for improved multimedia decoder
View Patent ↗Embodiments include systems and methods of improving processing in a decoder in a multimedia transmission system. Multimedia data may include one or more of motion video, audio, still images, or any other suitable type of audio-visual data. One embodiment includes a system and method of parsing fixed and variable length codes from a bit-wise stream of multi-media data by maintaining and reading the data in a processor aligned (e.g., word aligned) way. Another embodiment includes a system and method of decoding variable length codes, particular as received from such a variable length code using multiple levels of decoding tables to speed up decoder table lookup.
1. A method of processing received encoded multimedia data, the method comprising:
determining a number of bits available in a first buffer of encoded multimedia data from a received bitstream;
if reading a fixed length codeword, reading processor-aligned data from the bitstream into the first buffer, wherein the fixed length codeword comprises the determined available bits and bits associated with a portion of the processor-aligned data; and
if reading a variable length codeword, reading processor-unaligned data from the bitstream into the first buffer, wherein the variable length codeword comprises at least some of the available bits.
2. The method of claim 1 , further comprising:
if reading the fixed length codeword, copying the determined available bits into a second buffer prior to reading the processor-aligned data and then copying bits associated with the portion of the processor-aligned data from the first buffer to the second buffer.
3. The method of claim 1 , wherein reading processor unaligned data comprises reading 16 bits and reading processor-aligned data comprises reading 32 bits.
4. The method of claim 1 , further comprising:
decoding the variable length codeword;
updating the number of bits available in the first buffer based at least in part on the length of the decoded variable length codeword; and
adjusting the content of the first buffer to align data in the bitstream.
5. The method of claim 4 , wherein decoding the variable length codeword comprises:
identifying first decoding data in a first data structure based at least in part on data in the first buffer; and
determining whether the first decoding data is indicative of a second data structure comprising decoding data.
6. The method of claim 4 , wherein adjusting the content of the first buffer to align data in the bitstream comprises reading processor-unaligned data from the bitstream.
7. The method of claim 4 , wherein adjusting the content of the first buffer to align data in the bitstream comprises returning the processor-unaligned data to the bitstream.
8. The method of claim 1 , wherein reading processor-aligned data from the bitstream of encoded multimedia data comprises reordering bytes of data within a word.
9. The method of claim 8 , wherein reordering bytes of data within a word comprises reordering data from a big-endian format into a little-endian format.
10. A computer readable medium for embodying a method for processing multimedia data, the method comprising:
determining a number of bits available in a first buffer of encoded multimedia data from a received bitstream;
if reading a fixed length codeword, reading processor-aligned data from the bitstream into the first buffer, wherein the fixed length codeword comprises the determined available bits and bits associated with a portion of the processor-aligned data; and
if reading a variable length codeword, reading processor-unaligned data from the bitstream into the first buffer, wherein the variable length codeword comprises at least some of the available bits.
11. The computer readable medium of claim 10 , the method further comprising:
decoding the variable length codeword;
updating the number of bits available in the first buffer based at least in part on the length of the decoded variable length codeword; and
adjusting the content of the first buffer to align data in the bitstream.
12. The computer readable medium of claim 11 , wherein decoding the variable length codeword comprises:
identifying first decoding data in a first data structure based at least in part on data in the first buffer; and
determining whether the first decoding data is indicative of a second data structure comprising decoding data.
13. An apparatus for processing received encoded multimedia data, the apparatus comprising:
means for determining a number of bits available in a first buffer of encoded multimedia data from a received bitstream; and
means for reading a codeword, wherein if reading a fixed length codeword, said means for reading reads processor-aligned data from the bitstream into the first buffer, wherein the fixed codeword comprises the determined available bits and bits associated with a portion of the processor-aligned data, and wherein if reading a variable length codeword, said means for reading reads processor-unaligned data from the bitstream into the first buffer, wherein the variable length codeword comprises at least some of the available bits.
14. The apparatus of claim 13 , wherein said means for reading further comprising means for copying the determined available bits into a second buffer prior to reading the processor-aligned data and then copying bits associated with the portion of the processor-aligned data from the first buffer to the second buffer.
15. The apparatus of claim 13 , wherein said means for reading processor unaligned data comprises means for reading 16 bits and reading processor-aligned data comprises reading 32 bits.
16. The apparatus of claim 13 , further comprising:
means for decoding the variable length codeword;
means for updating the number of bits available in the first buffer based at least in part on the length of the decoded variable length codeword; and
means for adjusting the content of the first buffer to align data in the bitstream.
17. The apparatus of claim 16 , wherein said means for decoding the variable length codeword comprises:
means for identifying first decoding data in a first data structure based at least in part on data in the first buffer; and
means for determining whether the first decoding data is indicative of a second data structure comprising decoding data.
18. The apparatus of claim 16 , wherein said means for adjusting the content of the first buffer to align data in the bitstream comprises means for reading processor-unaligned data from the bitstream.
19. The apparatus of claim 16 , wherein said means for adjusting the content of the first buffer to align data in the bitstream comprises means for returning the processor-unaligned data to the bitstream.
20. An apparatus for processing multimedia data, comprising:
a determiner configured to determine a number of bits available in a first buffer of encoded multimedia data from a received bitstream; and
a reader configured to, if reading a fixed length codeword, read processor-aligned data from the bitstream into the first buffer, wherein the fixed length codeword comprises the determined available bits and bits associated with a portion of the processor-aligned data, and, if reading a variable length codeword, read processor-unaligned data from the bitstream into the first buffer, wherein the variable length codeword comprises at least some of the available bits.
21. The apparatus of claim 20 , further comprising:
a copier configured to, if reading the fixed length codeword, copy the determined available bits into a second buffer prior to reading the processor-aligned data and then copying bits associated with the portion of the processor-aligned data from the first buffer to the second buffer.
22. The apparatus of claim 20 , wherein the reader is configured to read processor unaligned data comprising 16 bits of data and the reader is configured to read processor-aligned data comprising 32 bits of data.
23. The apparatus of claim 20 , further comprising:
a codeword decoder configured to decode the variable length codeword;
an updater configured to update the number of bits available in the first buffer based at least in part on the length of the decoded variable length codeword; and
an adjuster configured to adjust the content of the first buffer to align data in the bitstream.
24. The apparatus of claim 20 , further comprising:
an identifier configured to identify first decoding data in a first data structure based at least in part on data in the first buffer; and
a second determiner configured to determine whether the first decoding data is indicative of a second data structure comprising decoding data.
25. The apparatus of claim 24 , wherein the adjuster is configured to adjust the content of the first buffer to align data in the bitstream by at least in part reading processor-unaligned data from the bitstream.
26. The apparatus of claim 24 , wherein as part of adjusting the content of the first buffer to align data in the bitstream, the adjuster is further configure to return the processor-unaligned data to the bitstream.
27. The apparatus of claim 20 , wherein as part of reading processor-aligned data from the bitstream of encoded multimedia data, the reader is further configured to reorder bytes of data within a word.
28. A processor for processing multimedia data, the processor being configured to:
determine a number of bits available in a first buffer of encoded multimedia data from a received bitstream;
if reading a fixed length codeword, read processor-aligned data from the bitstream into the first buffer, wherein the fixed length codeword comprises the determined available bits and bits associated with a portion of the processor-aligned data; and
if reading a variable length codeword, read processor-unaligned data from the bitstream into the first buffer, wherein the variable length codeword comprises at least some of the available bits.
29. The processor of claim 28 , wherein said processor is further configured to, if reading the fixed length codeword, copy the determined available bits into a second buffer prior to reading the processor-aligned data and then copying bits associated with the portion of the processor-aligned data from the first buffer to the second buffer.
30. The processor of claim 28 , wherein the processor is further configured to:
identify first decoding data in a first data structure based at least in part on data in the first buffer; and
determine whether the first decoding data is indicative of a second data structure comprising decoding data.
31. The processor of claim 30 , wherein the processor is configured to adjust the content of the first buffer to align data in the bitstream by at least in part reading processor-unaligned data from the bitstream.
32. The processor of claim 30 , wherein as part of adjusting the content of the first buffer to align data in the bitstream, the processor is further configured to return the processor-unaligned data to the bitstream.
33. The processor of claim 28 , wherein as part of reading processor-aligned data from the bitstream of encoded multimedia data, the processor is further configured to reorder bytes of data within a word.