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

• US 8,255,211 B2
• Filed: 08/15/2005
• Issued: 08/28/2012
• 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:
  US11/660,893
• Publication Number:
  US 20080046253A1
• Time in Patent Office: 2,570 Days
• Field of Search: 704/200.1, 704219-230, 704500-504
• US Class Current: 704/229
• 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 encoding in which one or more audio signals are encoded into a 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 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, has a temporal envelope resolution limited by the block rate, comprising

comparing the temporal envelope of at least one audio signal and the temporal envelope of an estimated decoded reconstruction of each such at least one audio signal, which estimated reconstruction employs at least some of the audio information and at least some of the side information, representations of the results of comparing being useful for improving the temporal envelope resolution of at least some of the audio information when decoded.

2. A method according to claim 1, further comprising

outputting at least some of the representations of the results of comparing for use by a decoder or decoding process.

3. The method of claim 1 wherein a representation of the results of comparing is expressed as a set of coefficients of a filter, which filter, when applied to a decoded reconstruction of an input signal, would result in the signal having a temporal envelope with an improved resolution.

4. The method of claim 3, wherein the filter, when applied to a decoded reconstruction of an input signal, would reshape the signal so that it more closely replicates the temporal envelope of the original signal.

5. The method of claim 3 wherein the improved resolution is a resolution finer than the block rate.

6. The method of claim 3 wherein said coefficients are coefficients of a Wiener filter.

7. A method for audio signal encoding and decoding in which one or more input audio signals are encoded into a bitstream comprising audio information and side information relating to the audio information and useful in decoding the bitstream, the bitstream is received and the audio information is decoded using the side information to provide one or more output audio signals, the encoding and decoding including processing that divides each of the one or more input audio signals and the decoded bitstream, respectively, into time blocks, the encoding updating at least some of the side information no more frequently than the block rate, such that the audio information, when decoded, has a temporal envelope having a resolution limited by the block rate, comprising

comparing the temporal envelope of at least one input audio signal and the temporal envelope of an estimated decoded reconstruction of each such 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, the comparing providing a representation of the results of comparing, such representations being useful for improving the temporal envelope resolution of at least some of the audio information when decoded,

outputting at least some of the representations, and

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

9. The method of claim 7 or claim 8 wherein the estimated reconstruction is the same as at least a portion of the decoding.

8. A method for audio signal decoding in which one or more input audio signals have been encoded into a 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 temporal envelope resolution limited by the block rate, the encoding further including comparing the temporal envelope of at least one input audio signal and the temporal envelope of an estimated decoded reconstruction of each such 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, the comparing providing a representation of the results of comparing, such representations being useful for improving the temporal envelope resolution of at least some of the audio information when decoded, and the encoding further including outputting at least some of the representations, comprising

receiving the bitstream, and

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

10. An audio signal encoder in which one or more audio signals are encoded into a 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 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, has a temporal envelope resolution limited by the block rate, comprising

means for comparing the temporal envelope of at least one audio signal and the temporal envelope of an estimated decoded reconstruction of each such at least one audio signal, which estimated reconstruction employs at least some of the audio information and at least some of the side information, representations of the results of comparing being useful for improving the temporal envelope resolution of at least some of the audio information when decoded, and

means for outputting at least some of the representations of the results of comparing for use by a decoder or decoding process.

11. An audio signal encoding and decoding system in which one or more input audio signals are encoded into a bitstream comprising audio information and side information relating to the audio information and useful in decoding the bitstream, the bitstream is received and the audio information is decoded using the side information to provide one or more output audio signals, the encoding and decoding including processing that divides each of the one or more input audio signals and the decoded bitstream, respectively, into time blocks, the encoding updating at least some of the side information no more frequently than the block rate, such that the audio information, when decoded, has a temporal envelope having a resolution limited by the block rate, comprising

means for comparing the temporal envelope of at least one input audio signal and the temporal envelope of an estimated decoded reconstruction of each such 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, the comparing providing a representation of the results of comparing, such representations being useful for improving the temporal envelope resolution of at least some of the audio information when decoded,

means for outputting at least some of the representations, and

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

12. A audio signal decoder in which one or more input audio signals have been encoded into a 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 temporal envelope resolution limited by the block rate, the encoding further including comparing the temporal envelope of at least one input audio signal and the temporal envelope of an estimated decoded reconstruction of each such 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, the comparing providing a representation of the results of comparing, such representations being useful for improving the temporal envelope resolution of at least some of the audio information when decoded, and the encoding further including outputting at least some of the representations, comprising

means for receiving the bitstream, and

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