Techniques for distortion reducing multi-band compressor with timbre preservation
AssigneeDolby Laboratories Licensing Corporation
InventorAlan Jeffrey Seefeldt
Life of this patent
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Abstract
Distortion reducing multi-band compressor with timbre preservation is provided. Timbre preservation is achieved by determining a time-varying threshold in each of a plurality frequency bands as a function of a respective fixed threshold for the frequency band and, at least in part, an audio signal level and a fixed threshold outside such frequency band. If a particular frequency band receives significant gain reduction due to being above or approaching its fixed threshold, then a time-varying threshold of one or more other frequency bands are also decreased to receive some gain reduction. In a specific embodiment, time-varying thresholds can be computed from an average difference of the audio input signal in each frequency band and its respective fixed threshold.
Claims20
A method for audio presentation, the method comprising:
- splitting an audio signal into a plurality of frequency bands;
- determining a time-varying threshold for a first frequency band of the plurality of frequency bands, the time-varying threshold determined from a level of the audio signal and a fixed signal level threshold corresponding to each of a plurality of neighboring frequency bands;
- providing the time-varying threshold to a compression function element dedicated to the first frequency band;
- and
- audibly presenting an audio signal outputted from the compression function element.
An apparatus, comprising:
- a multi-band filterbank configured for splitting an audio signal into a plurality of frequency bands;
- a timbre preservation element configured for determining a time-varying threshold for a first frequency band of the plurality of frequency bands, the time-varying threshold determined from a level of the audio signal and a fixed signal level threshold corresponding to each of a plurality of neighboring frequency bands;
- and
- a compression function element configured for receiving the time-varying threshold from the timbre preservation element and for applying an amount of compression for the first frequency band based, at least in part, on the time-varying threshold.
A non-transitory storage medium having instructions stored thereon for controlling one or more devices to perform a method for audio presentation, the method comprising:
- splitting an audio signal into a plurality of frequency bands;
- determining a time-varying threshold for a first frequency band of the plurality of frequency bands, the time-varying threshold determined from a level of the audio signal and a fixed signal level threshold corresponding to each of a plurality of neighboring frequency bands;
- providing the time-varying threshold to a compression function element dedicated to the first frequency band;
- and
- audibly presenting an audio signal outputted from the compression function element.
Dependencies are inferred from the claim text.