Techniques for distortion reducing multi-band compressor with timbre preservation

Patent metadata

Field	Value
Publication number	US-9935599-B2
Application number	US-201615138810-A
Country	US
Kind code	B2
Filing date	Apr 26, 2016
Priority date	Mar 18, 2010
Publication date	Apr 3, 2018
Grant date	Apr 3, 2018

Abstract

Distortion reducing multi-hand 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.

First claim

What is claimed is:

1. 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 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, but not all of the plurality of frequency bands; and
providing the time-varying threshold to a compression function element dedicated to the frequency band; and
audibly presenting an audio signal outputted from the compression function element.

2. The method of claim 1 wherein the levels are estimated power levels.

3. The method of claim 1 wherein the splitting is performed by a multi-band filterbank.

4. A method for audio presentation, the method comprising:
splitting, by a multi-band filterbank, an audio signal into a plurality of frequency bands;
determining a time-varying threshold for a 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, but not all of the plurality of frequency bands; and
providing the time-varying threshold to a compression function element dedicated to the frequency band.

5. A method for audio presentation, the method comprising:
splitting, by a multi-band filterbank, an audio signal into a plurality of frequency bands;
determining a time-varying threshold for a frequency band of the plurality of frequency bands, the time-varying threshold being determined in part from a plurality of fixed signal level thresholds from neighboring frequency bands but not all of the plurality of frequency bands; and
providing the time-varying threshold to a compression function element dedicated to the frequency band.

6. The method of claim 5 further comprising audibly presenting an audio signal outputted from the compression function element.

7. The method of claim 1 , wherein the fixed signal level threshold is a fixed signal energy level threshold.

8. The method of claim 4 , wherein the fixed signal level threshold is a fixed signal energy level threshold.

9. The method of claim 5 , wherein the fixed signal level thresholds are fixed signal energy level thresholds.

10. The method of claim 4 , further comprising audibly presenting an audio signal outputted from the compression function element.

Assignees

• Dolby Laboratories Licensing Corp

Inventors

• Seefeldt Alan J

Classifications

• H03G9/025

  frequency-dependent volume compression or expansion, e.g. multiple-band systems (H03G9/10, H03G9/18 take precedence) · CPC title

• H03G9/005 Primary

  of digital or coded signals · CPC title

• H03G9/10 Primary

  for tone control and volume expansion or compression · CPC title

• H03G9/18

  for tone control and volume expansion or compression · CPC title

• H04R2430/03

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