Cue-based audio coding/decoding
Generic and specific C-to-E binaural cue coding (BCC) schemes are described, including those in which one or more of the input channels are transmitted as unmodified channels that are not downmixed at the BCC encoder and not upmixed at the BCC decoder. The specific BCC schemes described include 5-to-2, 6-to-5, 7-to-5, 6.1-to-5.1, 7.1-to-5.1, and 6.2-to-5.1, where “0.1” indicates a single low-frequency effects (LFE) channel and “0.2” indicates two LFE channels.
1. A method for decoding E transmitted audio channels to generate C playback audio channels, the method comprising:
(a) upmixing, for each of one or more different frequency bands, one or more of the E transmitted channels in a frequency domain to generate two or more of the C playback channels in the frequency domain, where C>E≧1;
(b) applying two or more cue codes to each of the one or more different frequency bands in the two or more playback channels in the frequency domain to generate two or more modified channels, wherein the two or more cue codes comprise at least two of inter-channel level difference (ICLD) data, inter-channel time difference (ICTD) data, and inter-channel correlation (ICC) data; and
(c) converting the two or more modified channels from the frequency domain into a time domain.
2. The invention of claim 1 , further comprising, prior to upmixing, converting the one or more of the E transmitted channels from the time domain to the frequency domain.
3. The invention of claim 1 , wherein E=1.
4. The invention of claim 1 , wherein E>1.
5. The invention of claim 1 , wherein each of the C playback channels is based on at least one of the E transmitted channels and the two or more cue codes.
6. The invention of claim 1 , wherein the two or more cue codes comprise ICC data.
7. The invention of claim 6 , wherein the two or more cue codes further comprise ICLD data.
8. The invention of claim 1 , wherein the upmixing comprises, for each of one or more different frequency bands, upmixing at least two of the E transmitted channels into at least one playback channel in the frequency domain.
9. The invention of claim 1 , wherein:
step (a) comprises upmixing, for each of two or more different frequency bands, one or more of the E transmitted channels in the frequency domain to generate the two or more of the C playback channels in the frequency domain; and
step (b) comprises applying the two or more cue codes to each of the two or more different frequency bands in the two or more playback channels in the frequency domain to generate the two or more modified channels.
10. The invention of claim 1 , wherein:
at least two of the C playback channels are based on only a single one of the E transmitted channels and at least two cue codes; and
at least one of the C playback channels is based on at least two of the E transmitted channels and at least one cue code.
11. The invention of claim 1 , wherein:
at least one of the C playback channels is based on only a single one of the E transmitted channels and independent of any cue codes; and
at least two of the C playback channels are based on only a single one of the E transmitted channels and at least two cue codes.
12. The invention of claim 1 , wherein:
at least one of the C playback channels is based on only a single one of the E transmitted channels and independent of any cue codes;
at least two of the C playback channels are based on only a single one of the E transmitted channels and at least two cue codes;
at least one of the C playback channels is based on only a single one of the E transmitted channels and at least one cue code; and
at least one of the C playback channels is based on at least two of the E transmitted channels and at least one cue code.
13. The invention of claim 1 , wherein:
at least two of the C playback channels are based on only a single one of the E transmitted channels and at least two cue codes; and
at least one of the C playback channels is based on at least two of the E transmitted channels and at least one cue code.
14. The invention of claim 1 , wherein:
at least one of the C playback channels is based on only a single one of the E transmitted channels and independent of any cue codes; and
at least two of the C playback channels are based on only a single one of the E transmitted channels and at least two cue codes.
15. The invention of claim 1 , wherein:
at least one of the C playback channels is based on only a single one of the E transmitted channels and independent of any cue codes;
at least two of the C playback channels are based on only a single one of the E transmitted channels and at least two cue codes;
at least one of the C playback channels is based on only a single one of the E transmitted channels and at least one cue code; and
at least one of the C playback channels is based on at least two of the E transmitted channels and at least one cue code.
16. An apparatus for decoding E transmitted audio channels to generate C playback audio channels, the apparatus comprising:
an upmixer that, for each of one or more different frequency bands, upmixes one or more of the E transmitted channels in a frequency domain to generate two or more of the C playback channels in the frequency domain, where C>E≧1;
a synthesizer that applies two or more cue codes to each of the one or more different frequency bands in the two or more playback channels in the frequency domain to generate two or more modified channels, wherein the two or more cue codes comprise at least two of inter-channel level difference (ICLD) data, inter-channel time difference (ICTD) data, and inter-channel correlation (ICC) data; and
one or more inverse filter banks that convert the two or more modified channels from the frequency domain into a time domain.
17. The invention of claim 16 , further comprising one or more filter banks that convert, prior to the upmixing, the one or more of the E transmitted channels from the time domain to the frequency domain.
18. The invention of claim 16 , wherein E=1.
19. The invention of claim 16 , wherein E>1.
20. The invention of claim 16 , wherein each of the C playback channels is based on at least one of the E transmitted channels and the two or more cue codes.
21. The invention of claim 16 , wherein the two or more cue codes comprise ICC data.
22. The invention of claim 21 , wherein the two or more cue codes further comprise ICLD data.
23. The invention of claim 16 , wherein the upmixer, for each of one or more different frequency bands, upmixes at least two of the E transmitted channels into at least one playback channel in the frequency domain.
24. The invention of claim 16 , wherein:
the upmixer upmixes, for each of two or more different frequency bands, one or more of the E transmitted channels in the frequency domain to generate the two or more of the C playback channels in the frequency domain; and
the synthesizer applies the two or more cue codes to each of the two or more different frequency bands in the two or more playback channels in the frequency domain to generate the two or more modified channels.
25. The invention of claim 16 , 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 upmixer, the synthesizer, and the one or more inverse filter banks.
26. A method for encoding C input audio channels to generate E transmitted audio channels, the method comprising:
providing two or more of the C input channels in a frequency domain;
generating two or more cue codes for each of one or more different frequency bands in the two or more input channels in the frequency domain, wherein the two or more cue codes comprise at least two of inter-channel level difference (ICLD) data, inter-channel time difference (ICTD) data, and inter-channel correlation (ICC) data; and
downmixing the C input channels to generate the E transmitted channels, where C>E≧1.