Temporal envelope shaping for spatial audio coding using frequency domain wiener filtering

• US 7,945,449 B2
• Filed: 07/31/2007
• Issued: 05/17/2011
• Est. Priority Date: 08/25/2004
• Status: Active Grant

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Inventors: Vinton, Mark Stuart, Seefeldt, Alan Jeffrey
• Primary Examiner(s): AZAD, ABUL K
• Application Number:
  US11/888,651
• Publication Number:
  US 20080033731A1
• Time in Patent Office: 1,386 Days
• Field of Search: 704/229, 704500-504
• US Class Current: 704/500
• CPC Class Codes: G10L 19/008 Multichannel audio signal coding or decoding using interchannel correlation to reduce redundancy, e.g. joint-stereo, intensity-coding or matrixing
• CPC Class Codes: G10L 19/02 using spectral analysis, e.g. transform vocoders or subband vocoders

Abstract

Certain types of parametric spatial coding encoders use interchannel amplitude differences, interchannel time differences, and interchannel coherence or correlation to build a parametric model of a multichannel soundfield that is used by a decoder to construct an approximation of the original soundfield. However, such a parametric model does not reconstruct the original temporal envelope of the soundfield'"'"'s channels, which has been found to be extremely important for some audio signals. The present invention provides for the reshaping the temporal envelope of one or more of the decoded channels in a spatial coding system to better match one or more original temporal envelopes.

Claims

1. A method for audio signal decoding in which one or more input audio signals have been encoded into a bitstream comprising:

receiving a bitstream, the bitstream comprising audio information and side information relating to the audio information and useful in decoding the bitstream, the encoding including processing that divides each of the one or more input audio signals into time blocks and updates at least some of the side information no more frequently than the block rate, such that the audio information, when decoded using the side information, has a resolution limited by the block rate, the encoding further including comparing an envelope of at least one input audio signal and an envelope of a signal based on the at least one input audio signal as encoded, the comparing providing a representation of the results of comparing, such representation being useful for improving the resolution of at least some of the audio information when decoded, and the encoding further including outputting at least some of the representations, and

decoding the bitstream, the decoding employing the audio information, the side information, and the outputted representations.

2. The method according to claim 1, wherein the signal based on at least one input audio signal as encoded comprises an estimated decoded reconstruction of the at least one input audio signal, which estimated reconstruction employs at least some of the audio information and at least some of the side information.

3. The method according to claim 1, wherein the compared envelopes comprise temporal envelopes.

4. The method according to claim 1, wherein the input audio signal comprises a frequency domain representation.

5. The method according to claim 1, wherein the input audio signal comprises a time domain representation.

6. An audio signal decoder in which one or more input audio signals have been encoded into a bitstream comprising:

an input receiving the bitstream, the bitstream comprising audio information and side information relating to the audio information and useful in decoding the bitstream, the encoding including processing that divides each of the one or more input audio signals into time blocks and updates at least some of the side information no more frequently than the block rate, such that the audio information, when decoded using the side information, has a resolution limited by the block rate, the encoding further including comparing an envelope of at least one input audio signal and an envelope of a signal based on the at least one input audio signal as encoded, the comparing providing a representation of the results of comparing, such representations being useful for improving the resolution of at least some of the audio information when decoded, and the encoding further including outputting at least some of the representations, and

a decoder decoding the bitstream, the decoder employing the audio information, the side information and the outputted representations.

7. The decoder according to claim 6, wherein the signal based on at least one input audio signal as encoded comprises an estimated decoded reconstruction of the at least one input audio signal, which estimated reconstructions employs at least some of the audio information and at least some of the side information.

8. The decoder according to claim 6, wherein the compared envelopes comprise temporal envelopes.

9. The decoder according to claim 6, wherein the input audio signal comprises a frequency domain representation.

10. The decoder according to claim 6, wherein the input audio signal comprises a time domain representation.

11. An audio decoder, comprising:

a bitstream receiving device configured to receive an encoded signal and extract encoded audio and side information from the encoded signal;

a decoder configured to decode the encoded audio;

a re-shaping device configured to re-shape the decoded audio based on at least part of the side information, wherein side information includes an envelope comparison of an envelope of an audio signal and an envelope of the encoded audio signal and is useful for improving the resolution of the decoded audio.

12. The audio decoder according to claim 11 wherein the decoder is configured to update the side information at a block rate of the encoded signal.

13. The audio decoder according to claim 11, wherein the decoder is configured to decode multiple audio channels from the encoded signal and re-shape each decoded audio channel using a reshaping comparison based on the corresponding decoded channel'"'"'s original audio signal.