Surround sound generation from a microphone array

A computer readable storage medium comprising instructions, which when executed with one or more processors, controls the one or more processors to perform a method, comprising the steps of:

• analyzing a signal from each of an array of microphones;
• wherein the microphone array comprises a plurality of omni-directional microphone capsules, which are spaced in a proximity to each other with a spacing between each of the microphone capsules that is small in relation to sound wavelengths that affect a mapping of a the microphone signals to an output signal that drives at least two loudspeakers;
• for at least one subset of microphone signals, estimating a time difference that characterizes the relative time delays between the signals in the subset;
• estimating a direction from which a microphone input from one or more acoustic sources, which relate to the microphone signals, arrives at each of the microphones, based at least in part on the estimated time differences;
• filtering the microphone signals in relation to at least one filter transfer function, which relates to one or more filters;
• wherein the filter transfer function comprises one or more of:
• a first transfer function component, which has a value that relates to a first spatial orientation related to the direction of the acoustic sources;
• and
• a second transfer function component, which has a value that relates to a second spatial orientation related to the direction of the acoustic sources;
• wherein the second spatial orientation is substantially orthogonal in relation to the first spatial orientation;
• and
• computing a signal with which to drive the at least two loudspeakers based, at least in part, on the filtering step.

A system, comprising:

• means for analyzing a signal from each of an array of microphones;
• wherein the microphone array comprises a plurality of omni-directional microphone capsules, which are spaced in a proximity to each other with a spacing between each of the microphone capsules that is small in relation to sound wavelengths that affect a mapping of a the microphone signals to an output signal that drives at least two loudspeakers;
• means for estimating, for at least one subset of microphone signals, a time difference that characterizes the relative time delays between the signals in the subset;
• means for estimating a direction from which a microphone input from one or more acoustic sources, which relate to the microphone signals, arrives at each of the microphones, based at least in part on the estimated time differences;
• means for filtering the microphone signals in relation to at least one filter transfer function, which relates to one or more filters associated with the filtering means;
• wherein the filter transfer function comprises one or more of:
• a first transfer function component, which has a value that relates to a first spatial orientation related to the direction of the acoustic sources;
• and
• a second transfer function component, which has a value that relates to a second spatial orientation related to the direction of the acoustic sources;
• wherein the second spatial orientation is substantially orthogonal in relation to the first spatial orientation;
• and
• means for computing a signal with which to drive the at least two loudspeakers based, at least in part, on a function of the filtering means.

A method for processing microphone input signals from an array of omni-directional microphone capsules, which are deployed on a handheld audio or audio/video capture device, to speaker output signals suitable for playback on a surround speaker system, the method comprising the steps of:

• estimating a front-back time difference between one or more front microphone signals and one or more rear microphone signals, the front-back time difference being normalized to a value in the range of approximately negative one to positive one;
• estimating a left-right time difference between one or more left microphone signals and one or more right microphone signals, said left-right time difference being normalized to a value in the range of approximately negative one to positive one;
• filtering each of the microphone input signal through one or more variable filters;
• summing the outputs of one or more variable filters;
• and
• generating each of the speaker output signals based on the summed variable filter outputs;
• wherein one or more of the variable filters has a transfer function that varies as a function of one or more of the front-back time difference or left-right time difference.

A system for processing microphone input signals from an array of omni-directional microphone capsules, which are deployed on a handheld audio or audio/video capture device, to speaker output signals suitable for playback on a surround speaker system, the system comprising:

• means for estimating a front-back time difference between one or more front microphone signals and one or more rear microphone signals, the front-back time difference being normalized to a value in the range of approximately negative one to positive one;
• means for estimating a left-right time difference between one or more left microphone signals and one or more right microphone signals, said left-right time difference being normalized to a value in the range of approximately negative one to positive one;
• means for filtering each of the microphone input signal through one or more variable filters;
• means for summing the outputs of one or more variable filters;
• and
• means for generating each of the speaker output signals based on the summed variable filter outputs;
• wherein one or more of the variable filters has a transfer function that varies as a function of one or more of the front-back time difference or left-right time difference.

A computer readable storage medium comprising instructions stored therewith, which when executed with one or more processors, controls the one or more processors to perform one or more of:

• control of one or more of:
• a use for a computer system;
• a process for processing microphone input signals from an array of omni-directional microphone capsules, which are deployed on a handheld audio or audio/video capture device, to speaker output signals suitable for playback on a surround speaker system, wherein the computer system use or the process comprises:
• estimating a front-back time difference between one or more front microphone signals and one or more rear microphone signals, the front-back time difference being normalized to a value in the range of approximately negative one to positive one;
• estimating a left-right time difference between one or more left microphone signals and one or more right microphone signals, said left-right time difference being normalized to a value in the range of approximately negative one to positive one;
• filtering each of the microphone input signal through one or more variable filters;
• summing the outputs of one or more variable filters;
• and
• generating each of the speaker output signals based on the summed variable filter outputs;
• wherein one or more of the variable filters has a transfer function that varies as a function of one or more of the front-back time difference or left-right time difference;
• or
• program or control configuration of a system, which comprises means for performing or controlling the process.

A method for processing the microphone input signals from an array of omni-directional microphone capsules, which are deployed on a handheld audio or audio/video capture device, to speaker output signals suitable for playback on a surround speaker system, the method comprising the steps of:

• estimating a front-back time difference between one or more front microphone signals and one or more rear microphone signals, the front-back time difference being normalized to a value in the range of approximately negative one to positive one;
• estimating a left-right time difference between one or more left microphone signals and one or more right microphone signals, the left-right time difference being normalized to a value in the range of approximately negative one to positive one;
• forming a set of pre-processed microphone signals, each of which is formed as a sum of one or more of the microphone input signals each scaled by an input weighting factor;
• filtering each of the pre-processed microphone signals through one or more filters;
• forming a set of intermediate output signals, each of the intermediate output signals comprising a sum of the outputs of one or more filters, each scaled by an output weighting factor;
• and
• generating each of the speaker output signals from the weighted sum of the intermediate output signals;
• wherein one or more of the input weighting factors or output weighting factors comprises a function of one or more of the front-back time difference or the left-right time difference.

A system for processing the microphone input signals from an array of omni-directional microphone capsules, which are deployed on a handheld audio or audio/video capture device, to speaker output signals suitable for playback on a surround speaker system, the system comprising:

• means for estimating a front-back time difference between one or more front microphone signals and one or more rear microphone signals, the front-back time difference being normalized to a value in the range of approximately negative one to positive one;
• means for estimating a left-right time difference between one or more left microphone signals and one or more right microphone signals, the left-right time difference being normalized to a value in the range of approximately negative one to positive one;
• means for forming a set of pre-processed microphone signals, each of which is formed as a sum of one or more of the microphone input signals each scaled by an input weighting factor;
• means for filtering each of the pre-processed microphone signals through one or more filters;
• means for forming a set of intermediate output signals, each of the intermediate output signals comprising a sum of the outputs of one or more filters, each scaled by an output weighting factor;
• and
• means for generating each of the speaker output signals from the weighted sum of the intermediate output signals;
• wherein one or more of the input weighting factors or output weighting factors comprises a function of one or more of the front-back time difference or the left-right time difference.

A computer readable storage medium comprising instructions stored therewith, which when executed with one or more processors, controls the one or more processors to perform one or more of:

• control of one or more of:
• a use for a computer system;
• a process for processing the microphone input signals from an array of omni-directional microphone capsules, which are deployed on a handheld audio or audio/video capture device, to speaker output signals suitable for playback on a surround speaker system, the method comprising the steps of:
• estimating a front-back time difference between one or more front microphone signals and one or more rear microphone signals, the front-back time difference being normalized to a value in the range of approximately negative one to positive one;
• estimating a left-right time difference between one or more left microphone signals and one or more right microphone signals, the left-right time difference being normalized to a value in the range of approximately negative one to positive one;
• forming a set of pre-processed microphone signals, each of which is formed as a sum of one or more of the microphone input signals each scaled by an input weighting factor;
• filtering each of the pre-processed microphone signals through one or more filters;
• forming a set of intermediate output signals, each of the intermediate output signals comprising a sum of the outputs of one or more filters, each scaled by an output weighting factor;
• and
• generating each of the speaker output signals from the weighted sum of the intermediate output signals;
• wherein one or more of the input weighting factors or output weighting factors comprises a function of one or more of the front-back time difference or the left-right time difference;
• or
• program or control configuration of a system, which comprises means for performing or controlling the process.