Methods for Controlling the Inter-Channel Coherence of Upmixed Audio Signals

Patent metadata

Field	Value
Publication number	US-2016005406-A1
Application number	US-201414767279-A
Country	US
Kind code	A1
Filing date	Jan 22, 2014
Priority date	Feb 14, 2013
Publication date	Jan 7, 2016
Grant date	—

Abstract

Audio characteristics of audio data corresponding to a plurality of audio channels may be determined. The audio characteristics may include spatial parameter data. Decorrelation filtering processes for the audio data may be based, at least in part, on the audio characteristics. The decorrelation filtering processes may cause a specific inter-decorrelation signal coherence (“IDC”) between channel-specific decorrelation signals for at least one pair of channels. The channel-specific decorrelation signals may be received and/or determined. Inter-channel coherence (“ICC”) between a plurality of audio channel pairs may be controlled. Controlling ICC may involve at receiving an ICC value and/or determining an ICC value based, at least partially, on the spatial parameter data. A set of IDC values may be based, at least partially, on the set of ICC values. A set of channel-specific decorrelation signals, corresponding with the set of IDC values, may be synthesized by performing operations on the filtered audio data.

First claim

1 - 100 . (canceled)

101 . A method, comprising:
receiving audio data corresponding to a plurality of audio channels; determining audio characteristics of the audio data, the audio characteristics including spatial parameter data and at least one of tonality information or transient information; determining at least two channel-specific decorrelation filtering processes for the audio data based, at least in part, on the tonality information or the transient information, the channel-specific decorrelation filtering processes causing a specific inter-decorrelation signal coherence (“IDC”), which is a measure of correlation between decorrelation signals, between channel-specific decorrelation signals for at least one pair of channels, each of the channel-specific decorrelation filtering processes comprising applying a decorrelation filter to at least a portion of a corresponding audio channel of the audio data to produce filtered audio data, the channel-specific decorrelation signals being produced by performing operations on the filtered audio data; applying the channel-specific decorrelation filtering processes to at least a portion of the audio data to produce the channel-specific decorrelation signals; determining mixing parameters based, at least in part, on the spatial parameter data; and mixing the channel-specific decorrelation signals with a direct portion of the audio data according to the mixing parameters, the direct portion corresponding to the portion to which the decorrelation filter is applied.

102 . An apparatus, comprising:
an interface; and a logic system configured for:
receiving audio data corresponding to a plurality of audio channels;
determining audio characteristics of the audio data, the audio characteristics including spatial parameter data and at least one of tonality information or transient information;
determining at least two channel specific decorrelation filtering processes for the audio data based, at least in part, on the tonality information or the transient information, the channel-specific decorrelation filtering processes causing a specific inter-decorrelation signal coherence (“IDC”), which is a measure of correlation between decorrelation signals, between channel-specific decorrelation signals for at least one pair of channels, each of the channel-specific decorrelation filtering processes comprising applying a decorrelation filter to at least a portion of a corresponding audio channel of the audio data to produce filtered audio data, the channel-specific decorrelation signals being produced by performing operations on the filtered audio data;
applying the decorrelation filtering processes to at least a portion of the audio data to produce the channel-specific decorrelation signals;
determining mixing parameters based, at least in part, on the spatial parameter data; and
mixing the channel-specific decorrelation signals with a direct portion of the audio data according to the mixing parameters, the direct portion corresponding to the portion to which the decorrelation filter is applied.

103 . The apparatus of claim 102 , wherein the receiving process involves receiving information regarding a number of output channels and wherein the process of determining at least two decorrelation filtering processes for the audio data is based, at least in part, on the number of output channels.

104 . The apparatus of claim 103 , wherein the receiving process involves receiving audio data corresponding to N input audio channels and wherein the logic system is further configured for:
determining that the audio data for N input audio channels will be downmixed or upmixed to audio data for K output audio channels; and producing decorrelated audio data corresponding to the K output audio channels.

105 . The apparatus of claim 103 , wherein the receiving process involves receiving audio data for N input audio channels and wherein the logic system is further configured for:
downmixing or upmixing the audio data for N input audio channels to audio data for M intermediate audio channels; producing decorrelated audio data for the M intermediate audio channels; and downmixing or upmixing the decorrelated audio data for the M intermediate audio channels to decorrelated audio data for K output audio channels.

106 . The apparatus of claim 105 , wherein determining the two decorrelation filtering processes for the audio data is based, at least in part, on the number M of intermediate audio channels.

107 . The apparatus of claim 105 , wherein the decorrelation filtering processes are determined based, at least in part, on M-to-K mixing equations.

108 . The apparatus of claim 102 , wherein the logic system is further configured for controlling inter-channel coherence (“ICC”) between a plurality of audio channel pairs.

109 . The apparatus of claim 102 , wherein the process of applying the decorrelation filtering processes to at least a portion of the audio data involves applying the same decorrelation filter to audio data for a plurality of channels to produce the filtered audio data and multiplying the filtered audio data corresponding to a left channel or a right channel by −1.

110 . The apparatus of claim 109 , wherein the logic system is further configured for:
reversing a polarity of filtered audio data corresponding to a left surround channel with reference to the filtered audio data corresponding to the left-side channel; and reversing a polarity of filtered audio data corresponding to a right surround channel with reference to the filtered audio data corresponding to the right-side channel.

111 . The apparatus of claim 109 , wherein the processes of determining at least two decorrelation filtering processes for the audio data involve either determining that a different decorrelation filter will be applied to audio data for a center channel or determining that a decorrelation filter will not be applied to the audio data for the center channel.

112 . The apparatus of claim 102 , wherein the logic system is further configured for determining decorrelation signal synthesizing parameters based, at least in part, on the spatial parameter data.

113 . The apparatus of claim 112 , wherein the decorrelation signal synthesizing parameters are output-channel-specific decorrelation signal synthesizing parameters.

114 . The apparatus of claim 102 , wherein the mixing process involves using a non-hierarchal mixer to combine the channel-specific decorrelation signals with the direct portion of the audio data.

115 . The apparatus of claim 102 , wherein determining the audio characteristics involves receiving explicit audio characteristic information with the audio data and/or determining the audio characteristics involves receiving explicit audio characteristic information with the audio data.

116 . The apparatus of claim 102 , wherein the spatial parameter data comprises at least one of a representation of coherence between individual discrete channels and a coupling channel, and a representation of coherence between pairs of individual discrete channels.

117 . The apparatus of claim 102 , wherein the logic system is further configured for providing the mixing parameters to a direct signal and decorrelation signal mixer.

118 . The apparatus of claim 102 , wherein the mixing parameters are output-channel-specific mixing parameters.

119 . The apparatus of claim 118 , wherein the logic system is further configured for determining modified output-channel-specific mixing paramete

Assignees

• Dolby Lab Licensing Corp

Inventors

• Yen Kuan-Chieh
• Melkote Vinay
• Fellers Matthew
• Davidson Grant A

Classifications

• G10L19/008 Primary

  Multichannel audio signal coding or decoding using interchannel correlation to reduce redundancy, e.g. joint-stereo, intensity-coding or matrixing · CPC title

• H04S5/00

  Pseudo-stereo systems, e.g. in which additional channel signals are derived from monophonic signals by means of phase shifting, time delay or reverberation · CPC title

• H04S2420/03

  Application of parametric coding in stereophonic audio systems · CPC title

• H04S2400/03

  Aspects of down-mixing multi-channel audio to configurations with lower numbers of playback channels, e.g. 7.1 -> 5.1 (H04S2400/01 takes precedence) · CPC title

• H04S3/008

  in which the audio signals are in digital form, i.e. employing more than two discrete digital channels (data reduction aspects thereof based on psychoacoustics G10L19/02) · CPC title