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

• US 20080040103A1
• Filed: 07/31/2007
• Published: 02/14/2008
• Est. Priority Date: 08/25/2004
• Status: Abandoned Application

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Inventors: Seefeldt, Alan, Vinton, Mark
• Application Number:
  US11/888,646
• Publication Number:
  US 20080040103A1
• Time in Patent Office: Days
• US Class Current: 704/212
• 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 restoring an envelope of a synthesized output signal, comprising:

a) receiving a spatially encoded bitstream comprising a downmix signal and envelope side information, wherein,

the downmix signal comprises audio information divided into time slots and the envelope side information relates to the audio information and is useful in decoding the bitstream,

the envelope side information is based on comparing an envelope of an input signal and an envelope of the downmix signal, and

b) decoding the bitstream, wherein the decoding employs the audio information and the envelope side information to restore the envelope.

2. The method according to claim 1 wherein a granularity of the time slots relates to an envelope of an input channel with respect to an envelope of the downmix signal.

3. The method according to claim 1, wherein decoding the bitstream includes controlling decorrelating re-shaping filters with said envelope side information.

4. The method according to claim 1, wherein a comparison of an envelope of an input signal and an envelope of the downmix signal comprises a representation in the side information of the compared envelopes.

5. The method according to claim 1, wherein the spatially encoded bitstream comprises a bitstream constructed from one or more input audio signals.

6. The method according to claim 5, wherein the one or more input audio signals comprises a multi-channel sound field.

7. The method according to claim 1, wherein the time slots in which the audio information is divided each comprise a block of time.

8. The method according to claim 7, wherein the time slot granularity comprises a resolution limited by a rate of the time blocks.

9. The method according to claim 7, wherein the time blocks have a block rate that limits a resolution of the envelope side information.

10. The method according to claim 1, wherein the comparison of an envelope of an input signal and an envelope of the downmix signal comprises a comparison of 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.