Bitstream syntax for multi-process audio decoding
An audio decoder provides a combination of decoding components including components implementing base band decoding, spectral peak decoding, frequency extension decoding and channel extension decoding techniques. The audio decoder decodes a compressed bitstream structured by a bitstream syntax scheme to permit the various decoding components to extract the appropriate parameters for their respective decoding technique.
1. A method of decoding a compressed audio bitstream containing syntax elements conforming to a bitstream syntax, the bitstream syntax defining a base coding layer and a frequency extension coding layer for coding a portion of audio content using a frequency extension coding, the method comprising:
reading the base coding layer and frequency extension coding layer of the compressed audio bitstream;
parsing a plurality of syntax elements from the frequency extension coding layer specifying parameters used in the frequency extension coding, wherein the parameters comprise parameters specifying frequency extension coding using a different transform window size than a base coding layer; and
processing coded audio content of the frequency extension coding layer to reconstruct the portion of audio content and forming an audio signal based on the reconstructed portion of audio content; and
outputting the audio signal.
2. The method of claim 1 wherein the parameters comprise parameters identifying tiles coded using frequency extension coding with a different transform window size than a based coding layer.
3. The method of claim 1 wherein the parameters comprise dynamic band configuration parameters specifying spectral band locations where frequency extension coding is applied.
4. The method of claim 1 wherein said dynamic band configuration parameters specify start and end positions of spectral bands coded using vector quantization techniques.
5. The method of claim 1 wherein the parameters comprise displacement vector search range, step size for displacement vector quantization, scale factor and codeword modifications.
6. The method of claim 1 , wherein processing the coded audio content of the frequency extension coding layer comprises applying an inverse vector quantization process to produce decoded spectral coefficients, and inverse transforming the decoded spectral coefficients to reconstruct the portion of audio content in the output audio signal.
7. The method of claim 1 , further comprising playing the output audio signal.
8. An audio decoder situated to receive a compressed audio bitstream containing syntax elements conforming to a bitstream syntax, the bitstream syntax defining a case coding layer and a frequency extension coding layer for coding a portion of audio content using a frequency extension coding, the audio decoder comprising:
a processor that reads the base coding layer and the frequency extension coding layer of the compressed audio bitstream, parses a plurality of syntax elements from the frequency extension coding layer specifying parameters used in the frequency extension coding, wherein the parameters comprise parameters specifying frequency extension coding using a different transform window size than a base coding layer, and processes the coded audio content of the frequency extension coding layer to reconstruct the portion of audio content in an output audio signal.
9. The audio decoder of claim 8 wherein the parameters comprise parameters identifying tiles coded using frequency extension coding with a different transform window size than a base coding layer.
10. The audio decoder of claim 8 wherein the parameters comprise dynamic band configuration parameters specifying spectral band locations where frequency extension coding is applied.
11. The audio decoder of claim 8 wherein said dynamic band configuration parameters specify start and end positions of spectral bands coded using vector quantization techniques.
12. The audio decoder of claim 8 wherein the parameters comprise displacement vector search range, step size for displacement vector quantization, scale factor and codeword modifications.
13. The audio decoder of claim 8 , wherein the coded audio content of the frequency extension coding layer is processed by applying an inverse vector quantization process to produce decoded spectral coefficients, and the decoded spectral coefficients are inverse transformed to reconstruct the portion of audio content in the output audio signal.
14. At least one computer-readable storage device having stored thereon computer-executable instructions for a method of decoding a compressed audio bitstream containing syntax elements conforming to a bitstream syntax, the bitstream syntax defining a base coding layer and a frequency extension coding layer for coding a portion of audio content using a frequency extension coding, the method comprising:
reading the base coding layer and frequency extension coding layer of the compressed audio bitstream;
parsing a plurality of syntax elements from the frequency extension coding layer specifying parameters used in the frequency extension coding, wherein the parameters comprise parameters specifying frequency extension coding using a different transform window size than a base coding layer;
processing coded audio content of the frequency extension coding layer to reconstruct the portion of audio content in an output audio signal;
playing the output audio signal.
15. The at least one computer-readable storage device of claim 14 , wherein the parameters comprise parameters identifying tiles coded using frequency extension coding with a different transform window size than a base coding layer.
16. The at least one computer-readable storage device of claim 14 , wherein the parameters comprise dynamic band configuration parameters specifying spectral band locations where frequency extension coding is applied.
17. The at least one computer-readable storage device of claim 14 , wherein said dynamic band configuration parameters specify start and end positions of spectral bands coded using vector quantization techniques.
18. The at least one computer-readable storage device of claim 14 , wherein the parameters comprise displacement vector search range, step size for displacement vector quantization, scale factor and codeword modifications.
19. The at least one computer-readable storage device of claim 14 , wherein processing the coded audio content of the frequency extension coding layer comprises applying an inverse vector quantization process to produce decoded spectral coefficients, and inverse transforming the decoded spectral coefficients to reconstruct the portion of audio content in the output audio signal.
20. The at least one computer-readable storage device of claim 14 , wherein the bitstream syntax further defines a channel extension coding layer for coding a portion of audio content using a channel extension coding, the method further comprising:
parsing a plurality of syntax elements from the channel extension coding layer specifying parameters used in die channel extension coding; and
processing coded audio content of the channel extension coding layer to reconstruct the portion of audio content in the output audio signal.