High quality time-scaling and pitch-scaling of audio signals

A method for time scaling and/or pitch shifting a plurality of audio signal channels, comprising

• dividing the audio signal in each channel into auditory events,
• determining combined auditory events, each having a boundary where an auditory event boundary occurs in any of the audio signal channels, and
• time scaling and/or pitch shifting processing all of said audio signal channels within a combined auditory event, whereby processing is within an auditory event or a portion of an auditory event in each channel,
• wherein said dividing the audio signal in each channel into auditory events comprises, in each channel, identifying a continuous succession of auditory event boundaries in the audio signal, in which every change in spectral content with respect to time exceeding a threshold defines a boundary, wherein each auditory event is an audio segment between adjacent boundaries and there is only one auditory event between such adjacent boundaries, each boundary representing the end of the preceding event and the beginning of the next event such that a continuous succession of auditory events is obtained, wherein neither auditory event boundaries, auditory events, nor any characteristics of an auditory event are known in advance of identifying the continuous succession of auditory event boundaries and obtaining the continuous succession of auditory events.

A method for time scaling and/or pitch shifting an audio signal, comprising

• dividing said audio signal into auditory events,
• analyzing said auditory events using a psychoacoustic criterion to identify those auditory events in which the time scaling and/or pitch shifting processing of the audio signal would be inaudible or minimally audible, and
• time-scaling and/or pitch shifting processing within an auditory event identified as one in which the time scaling and/or pitch shifting processing of the audio signal would be inaudible or minimally audible,
• wherein said dividing said audio signal into auditory events comprises identifying a continuous succession of auditory event boundaries in the audio signal, in which every change in spectral content with respect to time exceeding a threshold defines a boundary, wherein each auditory event is an audio segment between adjacent boundaries and there is only one auditory event between such adjacent boundaries, each boundary representing the end of the preceding event and the beginning of the next event such that a continuous succession of auditory events is obtained, wherein neither auditory event boundaries, auditory events, nor any characteristics of an auditory event are known in advance of identifying the continuous succession of auditory event boundaries and obtaining the continuous succession of auditory events.

A method for time scaling and/or pitch shifting multiple channels of audio signals, comprising

• dividing the audio signal in each channel into auditory events,
• analyzing said auditory events using at least one psychoacoustic criterion to identify those auditory events in which the time scaling mid/or pitch shifting processing of the audio signal would be inaudible or minimally audible,
• determining combined auditory events, each having a boundary where an auditory event boundary occurs in the audio signal of any of the channels, and
• time-scaling and/or pitch shifting processing within a combined auditory event identified as one in which the time scaling and/or pitch shifting processing in the multiple channels of audio signals would be inaudible or minimally audible,
• wherein said dividing the audio signal in each channel into auditory events comprises, in each channel, identifying a continuous succession of auditory event boundaries in the audio signal, in which every change in spectral content with respect to time exceeding a threshold defines a boundary, wherein each auditory event is an audio segment between adjacent boundaries and there is only one auditory event between such adjacent boundaries, each boundary representing the end of the preceding event and the beginning of the next event such that a continuous succession of auditory events is obtained, wherein neither auditory event boundaries, auditory events, nor any characteristics of an auditory event are known in advance of identifying the continuous succession of auditory event boundaries and obtaining the continuous succession of auditory events.