Processing of microphone signals for spatial playback
AssigneeDolby Laboratories Licensing Corporation
InventorDavid S. McGrath
Life of this patent
Estimating the term…
Abstract
Disclosed are methods and systems which convert a multi-microphone input signal to a multichannel output signal making use of a time-and frequency-varying matrix. For each time and frequency tile, the matrix is derived as a function of a dominant direction of arrival and a steering strength parameter. Likewise, the dominant direction and steering strength parameter are derived from characteristics of the multi-microphone signals, where those characteristics include values representative of the inter-channel amplitude and group-delay differences.
Claims2
A method of processing audio, comprising:
- receiving an input signal including a plurality of microphone signals;
- determining a mixing matrix based on characteristics of the input signal;
- and
- mixing the input signal according to the mixing matrix to produce a multichannel audio output signal including a plurality of output channels, wherein determining the mixing matrix comprises:
- calculating a covariance matrix based on a frequency representation of the input signal, wherein the covariance matrix is smoothed over a predetermined time window;
- based on the covariance matrix:
- determining a vector representative of a dominant direction of arrival and a parameter representative of a degree to which the input signal appears to contain a dominant direction of arrival;
- and
- determining the mixing matrix based on a weighted sum of a first matrix that is independent of the dominant direction of arrival and based on a second matrix that correlates to the dominant direction of arrival, wherein the first matrix is weighted by a first weight that decreases for an increase in value of the parameter, and wherein the second matrix is weighted by a second weight that increases for an increase in value of the parameter.
A system comprising:
- one or more processors;
- and
- a non-transitory computer readable medium storing instructions that, when executed by the one or more processors, cause the one or more processors to perform operations of processing audio, the operations comprising:
- receiving an input signal including a plurality of microphone signals;
- determining a mixing matrix based on characteristics of the input signal;
- and
- mixing the input signal according to the mixing matrix to produce a multichannel audio output signal including a plurality of output channels, wherein determining the mixing matrix comprises:
- calculating a covariance matrix based on a frequency representation of the input signal, wherein the covariance matrix is smoothed over a predetermined time window;
- based on the covariance matrix:
- determining a vector representative of a dominant direction of arrival and a parameter representative of a degree to which the input signal appears to contain a dominant direction of arrival;
- and
- determining the mixing matrix based on a weighted sum of a first matrix that is independent of the dominant direction of arrival and based on a second matrix that correlates to the dominant direction of arrival, wherein the first matrix is weighted by a first weight that decreases for an increase in value of the parameter, and wherein the second matrix is weighted by a second weight that increases for an increase in value of the parameter.
Dependencies are inferred from the claim text.