Compact side information for parametric coding of spatial audio
View Patent ↗At an audio encoder, cue codes are generated for one or more audio channels, wherein a combined cue code (e.g., a combined inter-channel correlation (ICC) code) is generated by combining two or more estimated cue codes, each estimated cue code estimated from a group of two or more channels. At an audio decoder, E transmitted audio channel(s) are decoded to generate C playback audio channels. Received cue codes include a combined cue code (e.g., a combined ICC code). One or more transmitted channel(s) are upmixed to generate one or more upmixed channels. One or more playback channels are synthesized by applying the cue codes to the one or more upmixed channels, wherein two or more derived cue codes are derived from the combined cue code, and each derived cue code is applied to generate two or more synthesized channels.
1. A machine-implemented method for encoding audio channels, the method comprising:
the machine generating one or more cue codes for two or more audio channels, wherein:
at least one cue code is a combined cue code generated by combining two or more estimated cue codes; and
each estimated cue code is estimated from a group of two or more of the audio channels; and
the machine transmitting the one or more cue codes.
2. The method of claim 1 , further comprising transmitting E transmitted audio channel(s) corresponding to the two or more audio channels, where E≧1.
3. The method of claim 2 , wherein:
the two or more audio channels comprise C input audio channels, where C>E; and
the C input channels are downmixed to generate the E transmitted channel(s).
4. The method of claim 1 , wherein the one or more cue codes are transmitted to enable a decoder to perform synthesis processing during decoding of E transmitted channel(s) based on the combined cue code, wherein the E transmitted audio channel(s) correspond to the two or more audio channels, where E≧1.
5. The method of claim 1 , wherein the one or more cue codes comprise one or more of a combined inter-channel correlation (ICC) code, a combined inter-channel level difference (ICLD) code, and a combined inter-channel time difference (ICTD) code.
6. The method of claim 1 , wherein the combined cue code is generated as an average of the two or more estimated cue codes.
7. The method of claim 6 , wherein the combined cue code is generated as a weighted average of the two or more estimated cue codes.
8. The method of claim 7 , wherein:
each estimated cue code used to generate the combined cue code is associated with a weight factor used in generating the weighted average; and
the weight factor for each estimated cue code is based on power in the group of channels corresponding to the estimated cue code.
9. The method of claim 1 , wherein the combined cue code is a combined ICC code.
10. The method of claim 9 , wherein:
the two or more audio channels comprise a left channel, a left rear channel, a right channel, and a right rear channel;
a first estimated ICC code is generated from the left and left rear channels;
a second estimated ICC code is generated from the right and right rear channels; and
the combined ICC code is generated by combining the first and second estimated ICC codes.
11. The method of claim 1 , wherein each estimated cue code is estimated from a different group of two or more of the audio channels.
12. The method of claim 11 , wherein the combined cue code is not equivalent to any parameter stream containing the combined cue code.
13. Apparatus for encoding audio channels, the apparatus comprising:
means for generating one or more cue codes for two or more audio channels, wherein:
at least one cue code is a combined cue code generated by combining two or more estimated cue codes; and
each estimated cue code is estimated from a group of two or more of the audio channels; and
means for transmitting the one or more cue codes.
14. The apparatus of claim 13 , wherein the combined cue code is generated as a weighted average of the two or more estimated cue codes.
15. The apparatus of claim 14 , wherein:
each estimated cue code used to generate the combined cue code is associated with a weight factor used in generating the weighted average; and
the weight factor for each estimated cue code is based on power in the group of channels corresponding to the estimated cue code.
16. The apparatus of claim 13 , wherein the combined cue code is a combined ICC code.
17. Apparatus for encoding C input audio channels to generate E transmitted audio channel(s), the apparatus comprising:
a code estimator adapted to generate one or more cue codes for two or more audio channels, wherein:
at least one cue code is a combined cue code generated by combining two or more estimated cue codes; and
each estimated cue code is estimated from a group of two or more of the audio channels; and
a downmixer adapted to downmix the C input channels to generate the E transmitted channel(s), where C>E≧1, wherein the apparatus is adapted to transmit information about the cue codes to enable a decoder to perform synthesis processing during decoding of the E transmitted channel(s).
18. The apparatus of claim 17 , wherein:
the apparatus is a system selected from the group consisting of a digital video recorder, a digital audio recorder, a computer, a satellite transmitter, a cable transmitter, a terrestrial broadcast transmitter, a home entertainment system, and a movie theater system; and
the system comprises the code estimator and the downmixer.
19. The apparatus of claim 17 , wherein the combined cue code is generated as a weighted average of the two or more estimated cue codes.
20. The apparatus of claim 19 , wherein:
each estimated cue code used to generate the combined cue code is associated with a weight factor used in generating the weighted average; and
the weight factor for each estimated cue code is based on power in the group of channels corresponding to the estimated cue code.
21. The apparatus of claim 17 , wherein the combined cue code is a combined ICC code.
22. A computer-readable storage medium, having encoded thereon program code, wherein, when the program code is executed by a computer, the computer implements a method for encoding audio channels, the method comprising:
the computer generating one or more cue codes for two or more audio channels, wherein:
at least one cue code is a combined cue code generated by combining two or more estimated cue codes; and
each estimated cue code is estimated from a group of two or more of the audio channels; and
the computer transmitting the one or more cue codes.
23. A machine-implemented method for decoding E transmitted audio channel(s) to generate C playback audio channels, where C>E≧1, the method comprising:
the machine receiving cue codes corresponding to the E transmitted channel(s), wherein:
at least one cue code is a combined cue code generated by combining two or more estimated cue codes; and
each estimated cue code estimated from a group of two or more audio channels corresponding to the E transmitted channel(s);
the machine upmixing one or more of the E transmitted channel(s) to generate one or more upmixed channels; and
the machine synthesizing one or more of the C playback channels by applying the cue codes to the one or more upmixed channels, wherein:
two or more derived cue codes are derived from the combined cue code; and
each derived cue code is applied to generate two or more synthesized channels.
24. The method of claim 23 , wherein the cue codes comprise one or more of a combined ICC code, a combined ICLD code, and a combined ICTD code.
25. The method of claim 23 , wherein the combined cue code is an average of the two or more estimated cue codes.
26. The method of claim 25 , wherein the combined cue code is a weighted average of the two or more estimated cue codes.
27. The method of claim 26 , wherein:
each estimated cue code used to generate the combined cue code is associated with a weight factor used in generating the weighted average; and
the weight factor for each estimated cue code is based on power in the group of channels corresponding to the estimated cue code.
28. The method of claim 23 , wherein the two or more derived cue codes are derived by:
deriving a weight factor for each group of two or more channels associated with an estimated cue code; and
deriving the two or more derived cue codes as a function of the combined cue code and two or more derived weight factors.
29. The method of claim 28 , wherein each derived weight factor is derived by:
estimating power in the group of channels corresponding to an estimated cue code; and
deriving the weight factor based on the estimated powers for different groups of channels corresponding to different estimated cue codes.
30. The method of claim 23 , wherein the combined cue code is a combined ICC code.
31. The method of claim 30 , wherein:
the two or more audio channels comprise a left channel, a left rear channel, a right channel, and a right rear channel;
a first estimated ICC code is generated from the left and left rear channels;
a second estimated ICC code is generated from the right and right rear channels; and
the combined ICC code is generated by combining the first and second estimated ICC codes.
32. The method of claim 31 , wherein:
the combined ICC code is used to de-correlate synthesized left and left rear channels; and
the combined ICC code is used to de-correlate synthesized right and right rear channels.
33. Apparatus for decoding E transmitted audio channel(s) to generate C playback audio channels, where C>E≧1, the apparatus comprising:
means for receiving cue codes corresponding to the E transmitted channel(s), wherein:
at least one cue code is a combined cue code generated by combining two or more estimated cue codes; and
each estimated cue code estimated from a group of two or more audio channels corresponding to the E transmitted channel(s);
means for upmixing one or more of the E transmitted channel(s) to generate one or more upmixed channels; and
means for synthesizing one or more of the C playback channels by applying the cue codes to the one or more upmixed channels, wherein:
two or more derived cue codes are derived from the combined cue code; and
each derived cue code is applied to generate two or more synthesized channels.
34. The apparatus of claim 33 , wherein the combined cue code is a weighted average of the two or more estimated cue codes.
35. The apparatus of claim 34 , wherein:
each estimated cue code used to generate the combined cue code is associated with a weight factor used in generating the weighted average; and
the weight factor for each estimated cue code is based on power in the group of channels corresponding to the estimated cue code.
36. The apparatus of claim 33 , wherein the combined cue code is a combined ICC code.
37. Apparatus for decoding E transmitted audio channel(s) to generate C playback audio channels, where C>E≧1, the apparatus comprising:
a receiver adapted to receive cue codes corresponding to the E transmitted channel(s), wherein:
at least one cue code is a combined cue code generated by combining two or more estimated cue codes; and
each estimated cue code estimated from a group of two or more audio channels corresponding to the E transmitted channel(s);
an upmixer adapted to upmix one or more of the E transmitted channel(s) to generate one or more upmixed channels; and
a synthesizer adapted to synthesize one or more of the C playback channels by applying the cue codes to the one or more upmixed channels, wherein:
two or more derived cue codes are derived from the combined cue code; and
each derived cue code is applied to generate two or more synthesized channels.
38. The apparatus of claim 37 , wherein:
the apparatus is a system selected from the group consisting of a digital video player, a digital audio player, a computer, a satellite receiver, a cable receiver, a terrestrial broadcast receiver, a home entertainment system, and a movie theater system; and
the system comprises the receiver, the upmixer, and the synthesizer.
39. The apparatus of claim 37 , wherein the combined cue code is a weighted average of the two or more estimated cue codes.
40. The apparatus of claim 39 , wherein:
each estimated cue code used to generate the combined cue code is associated with a weight factor used in generating the weighted average; and
the weight factor for each estimated cue code is based on power in the group of channels corresponding to the estimated cue code.
41. The apparatus of claim 37 , wherein the combined cue code is a combined ICC code.
42. A computer-readable storage medium, having encoded thereon program code, wherein, when the program code is executed by a computer, the computer implements a method for decoding E transmitted audio channel(s) to generate C playback audio channels, where C>E≧1, the method comprising:
the computer receiving cue codes corresponding to the E transmitted channel(s), wherein:
at least one cue code is a combined cue code generated by combining two or more estimated cue codes; and
each estimated cue code estimated from a group of two or more audio channels corresponding to the E transmitted channel(s);
the computer upmixing one or more of the E transmitted channel(s) to generate one or more upmixed channels; and
the computer synthesizing one or more of the C playback channels by applying the cue codes to the one or more upmixed channels, wherein:
two or more derived cue codes are derived from the combined cue code; and
each derived cue code is applied to generate two or more synthesized channels.