Spatial audio encoding and reproduction of diffuse sound
View Patent ↗A method and apparatus processes multi-channel audio by encoding, transmitting or recording “dry” audio tracks or “stems” in synchronous relationship with time-variable metadata controlled by a content producer and representing a desired degree and quality of diffusion. Audio tracks are compressed and transmitted in connection with synchronized metadata representing diffusion and preferably also mix and delay parameters. The separation of audio stems from diffusion metadata facilitates the customization of playback at the receiver, taking into account the characteristics of local playback environment.
1. A method for decoding an encoded digital audio signal containing audio data and a plurality of metadata parameters, comprising:
demultiplexing the encoded digital audio signal to unpack the plurality of metadata parameters from the encoded digital audio signal and separate the audio data into a plurality of audio channels;
decoding and processing the plurality of metadata parameters to determine which channels of the plurality of audio channels are to be filtered to obtain selected channels;
decoding the audio data of the encoded digital audio signal to obtain a decoded audio signal;
processing the selected channels of the plurality of audio channels to include a spatially diffuse effect to obtain filtered audio channels;
receiving playback parameters defining a unique local acoustic environment that impacts the spatially diffuse effect to compensate for spatially diffuse deviations that occur when the decoded audio signal is played back in the unique local acoustic environment;
mixing the filtered audio channels based on the plurality of metadata parameters and the playback parameters to obtain output audio channels; and
playing back the output audio channels in the unique local acoustic environment.
2. The method of claim 1 , further comprising processing the encoded digital audio signal prior to encoding with a perceptually diffuse audio effect configured in response to at least one of the plurality of metadata parameters.
3. The method of claim 1 , further comprising playing back the decoded audio signal over a monitoring system for verification of the spatially diffuse effect.
4. The method of claim 1 , wherein decoding the plurality of metadata parameters further comprises:
obtaining at least one parameter from the plurality of metadata parameters representative of a reverberation decay time constant; and
configuring a reverberation effect in accordance with the reverberation decay time constant.
5. The method of claim 4 , wherein decoding the plurality of metadata parameters further comprises:
obtaining at least a second parameter from the plurality of metadata parameters that represents a desired reverberation density; and
configuring the reverberation effect to approximate the desired reverberation density.
6. The method of claim 5 , wherein decoding the plurality of metadata parameters further comprises obtaining at least one further parameter from the plurality of metadata parameters that represents a comb filter characteristic chosen from a set of count, length in stages, and gains for a set of feedback comb filters.