Adaptive inter-channel time difference estimation

An encoder comprising:

• processing circuitry;
• and
• memory coupled with the processing circuitry, wherein the memory includes instructions that when executed by the processing circuitry causes the encoder to perform operations comprising:
• receive a time domain audio input comprising audio input signals;
• process the audio input signals in frames to produce a mono mixdown signal and one or more stereo parameters;
• encode the mono mixdown signal on a frame-by-frame basis by:
• encode active content of the mono mixdown signal at a first bit rate until a pause period is detected in the audio input signals or mono mixdown signal;
• estimate ITD parameters during the encoding of active content based on a low-pass filtering of cross-spectra of the audio input signals or averaging of the cross-spectra;
• switch the encoding from the active encoding content to inactive encoding to encode background noise at a second bit rate during the pause period;
• estimate ITD parameters during the pause period based on a low-pass filtering of the cross-spectra of the audio input signals or averaging of the cross-spectra wherein the estimating is being configured to adapt to the audio input signals faster compared to when estimating the ITD parameters during the encoding of active content;
• and
• encode the estimated ITD parameters and other stereo parameters periodically during the pause period.

A computer program comprising program code to be executed by processing circuitry of an encoder, whereby execution of the program code causes the encoder to perform operations comprising:

• receive a time domain audio input comprising audio input signals;
• process the audio input signals in frames to produce a mono mixdown signal and one or more stereo parameters;
• encode the mono mixdown signal on a frame-by-frame basis by:
• encode of active content of the mono mixdown signal at a first bit rate until a pause period is detected in the audio input signals or mono mixdown signal;
• estimate ITD parameters during the encoding of active content based on a low-pass filtering of cross-spectra of the audio input signals or averaging of the cross-spectra;
• switch the encoding from the active encoding content to inactive encoding to encode background noise at a second bit rate during the pause period;
• estimate ITD parameters during the pause period based on a low-pass filtering of the cross-spectra of the audio input signals or averaging of the cross-spectra wherein the estimating is being configured to adapt to the audio input signals faster compared to when estimating the ITD parameters during the encoding of active content;
• and
• encode the estimated ITD parameters and other stereo parameters periodically during the pause period.

A computer program product comprising a non-transitory computer readable storage medium having program code, to be executed by processing circuitry of an encoder, whereby execution of the program code causes the encoder to perform operations comprising:

• receive a time domain audio input comprising audio input signals;
• process the audio input signals in frames to produce a mono mixdown signal and one or more stereo parameters;
• encode the mono mixdown signal on a frame-by-frame basis by:
• encode active content of the mono mixdown signal at a first bit rate until a pause period is detected in the audio input signals or mono mixdown signal;
• estimate ITD parameters during the encoding of active content based on a low-pass filtering of cross-spectra of the audio input signals or averaging of the cross-spectra;
• switch the encoding from the active encoding content to inactive encoding to encode background noise at a second bit rate during the pause period;
• estimate ITD parameters during the pause period based on a low-pass filtering of the cross-spectra of the audio input signals or averaging of the cross-spectra wherein the estimating is being configured to adapt to the audio input signals faster compared to when estimating the ITD parameters during the encoding of active content;
• and
• encode the estimated ITD parameters and other stereo parameters periodically during the pause period.