Methods for Audio Signal Transient Detection and Decorrelation Control

Patent metadata

Field	Value
Publication number	US-2016005405-A1
Application number	US-201414766957-A
Country	US
Kind code	A1
Filing date	Jan 22, 2014
Priority date	Feb 14, 2013
Publication date	Jan 7, 2016
Grant date	—

Abstract

Some audio processing methods may involve receiving audio data corresponding to a plurality of audio channels and determining audio characteristics of the audio data, which may include transient information. An amount of decorrelation for the audio data may be based, at least in part, on the audio characteristics. If a definite transient event is determined, a decorrelation process may be temporarily halted or slowed. Determining transient information may involve evaluating the likelihood and/or the severity of a transient event. In some implementations, determining transient information may involve evaluating a temporal power variation in the audio data. Explicit transient information may or may not be received with the audio data, depending on the implementation. Explicit transient information may include a transient control value corresponding to a definite transient event, a definite non-transient event or an intermediate transient control value.

First claim

1 - 81 . (canceled)

82 . A method, comprising:
receiving audio data corresponding to a plurality of audio channels; determining audio characteristics of the audio data, the audio characteristics comprising transient information; determining an amount of decorrelation for the audio data based, at least in part, on the audio characteristics; and processing the audio data according to a determined amount of decorrelation, wherein the process of determining transient information involves detecting a soft transient event which is a transient event determined according to an analysis of a portion of the audio data, wherein the process of processing the audio data involves:
applying a decorrelation filter to a portion of the audio data, to produce filtered audio data; and
mixing the filtered audio data with a portion of the received audio data according to a mixing ratio,
wherein the process of determining the amount of decorrelation comprises reducing an amount of decorrelation in response to detecting the soft transient event, reducing the amount of decorrelation involves modifying the mixing ratio, and modifying the mixing ratio is based, at least in part, on the transient information.

83 . The method of claim 82 , wherein determining the audio characteristics involves receiving explicit transient information with the audio data.

84 . The method of claim 83 , wherein the explicit transient information comprises at least one of a transient control value corresponding to a definite transient event or a transient control value corresponding to a definite non-transient event.

85 . The method of claim 83 , wherein the explicit transient information indicates a definite transient event, wherein processing the audio data comprises temporarily halting a decorrelation process.

86 . The method of claim 82 , wherein the process of detecting a soft transient event involves evaluating at least one of a likelihood or a severity of a transient event.

87 . The method of claim 82 , wherein the process of detecting a soft transient event involves detecting a temporal power variation of the audio data.

88 . The method of claim 84 , wherein the process of determining the amount of decorrelation involves modifying the mixing ratio based, at least in part, on the transient control value.

89 . The method of claim 82 , wherein determining the amount of decorrelation for the audio data involves attenuating an input to the decorrelation filter based on the transient information.

90 . The method of claim 82 , wherein processing the audio data comprises:
estimating a gain to be applied to the filtered audio data; and applying the gain to the filtered audio data.

91 . The method of claim 90 , wherein the process of determining the amount of decorrelation involves modifying the mixing ratio based on at least one of the transient information or the gain.

92 . The method of claim 82 , wherein the process of determining the audio characteristics involves determining at least one of a channel being block switched, a channel being out of coupling or channel coupling not being in use, and wherein determining an amount of decorrelation for the audio data comprises determining that a decorrelation process should be slowed or temporarily halted.

93 . An apparatus, comprising:
an interface; and a logic system configured for:
receiving, from the interface, audio data corresponding to a plurality of audio channels;
determining audio characteristics of the audio data, the audio characteristics comprising transient information;
determining an amount of decorrelation for the audio data based, at least in part, on the audio characteristics; and
processing the audio data according to a determined amount of decorrelation,
wherein determining transient information involves detecting a soft transient event which is a transient event determined according to an analysis of a portion of the audio data, wherein processing the audio data involves:
applying a decorrelation filter to a portion of the audio data, to produce filtered audio data; and
mixing the filtered audio data with a portion of the received audio data according to a mixing ratio,
wherein determining the amount of decorrelation comprises reducing an amount of decorrelation in response to detecting the soft transient event, reducing the amount of decorrelation involves modifying the mixing ratio, and modifying the mixing ratio is based, at least in part, on the transient information.

94 . A non-transitory medium having software stored thereon, the software including instructions for controlling an apparatus to perform the method of claim 82 .

95 . A method, comprising:
receiving audio data corresponding to a plurality of audio channels; determining audio characteristics of the audio data, the audio characteristics including transient information, wherein the transient information includes an intermediate transient control value indicating a transient value between a definite transient event and a definite non-transient event and corresponding to an intermediate likelihood or an intermediate severity of a transient event; and forming encoded audio data frames that include encoded transient information, wherein the process of determining transient information involves evaluating at least one of a likelihood or a severity of a transient event, and wherein the encoded transient information indicates the likelihood of a transient event or the severity of a transient event.

96 . The method of claim 95 , wherein the encoded transient information includes one or more control flags.

97 . The method of claim 95 , wherein the process of determining transient information involves evaluating a temporal power variation in the audio data.

98 . The method of claim 95 , wherein the encoded transient information includes a transient control value corresponding to a transient event and wherein the transient control value is subject to an exponential decay function.

99 . The method of claim 95 , wherein the transient information indicates that a decorrelation process should be temporarily slowed or halted.

100 . The method of claim 95 , wherein the transient information indicates that a mixing ratio of a decorrelation process should be modified.

101 . The method of claim 95 , wherein the transient information indicates that an amount of decorrelation in a decorrelation process should be temporarily reduced.

Assignees

• Dolby Lab Licensing Corp

Inventors

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

Classifications

• H04S2420/07

  Synergistic effects of band splitting and sub-band processing · CPC title

• G10H2250/225

  MDCT [Modified discrete cosine transform], i.e. based on a DCT of overlapping data · CPC title

• G10H7/008

  Means for controlling the transition from one tone waveform to another · CPC title

• 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