Binaural filters for monophonic compatibility and loudspeaker compatibility
First Claim
Patent Images
1. An apparatus for binauralizing a set of one or more audio input signals comprising:
- a binauralizer implementing one or more pairs of binaural filters, one respective pair for each of the audio signal inputs, each pair of binaural filters having a left ear output and a right ear output, each pair of binaural filters representable by a left ear binaural filter and a right ear binaural filter, respectively, each pair of binaural filters further representable by a sum filter and a difference filter related to the left and right ear binaural filters, each filter having a respective impulse response that characterizes the filter,wherein at least one pair of binaural filters is configured to spatialize its respective audio input signal to incorporate a direct response to a listener from a respective virtual speaker location, and to incorporate both early echoes and a reverberant response of a listening room, andwherein for the at least one pair of binaural filters configured to spatialize;
the time-frequency characteristics of the sum filter are different than the time-frequency characteristics of the difference filter, with the sum filter reverberation time smaller at all frequencies than each of;
the difference filter reverberation time, the left ear filter reverberation time, and the right ear filter reverberation time; and
the sum filter reverberation time varies more across different frequencies than the respective variation over frequencies of the left ear filter reverberation time and of the right ear filter reverberation time, with the sum filter reverberation time decreasing with increasing frequency,such that the one or more audio input signals filtered by the pair of binaural filters generate output signals that are perceived as spatialized when played through headphones and sound good when played monophonically after a monophonic mix achieved by downmixing or by playing over relatively closely spaced loudspeakers, wherein for the at least one pair of binaural filters, the transition of the sum filter impulse response to its negligible level occurs gradually over time in a frequency dependent manner over an initial time interval of the sum filter impulse response, wherein for the at least one pair of binaural filters, the sum filter decreases in frequency content from being initially full bandwidth towards a low frequency cutoff over the transition time interval.
1 Assignment
0 Petitions
Accused Products
Abstract
A method of processing at least one input signal by a set of binaural filters such that the outputs are playable over headphones to provide a sense of listening to sound in a listening room via one or more virtual speakers, with the further property that a monophonic mix down sounds good. Also an apparatus for processing the at least one input signals. Also a method of modifying a pair of binaural filters to achieve the property that a monophonic mix down sounds good, while still providing spatialization when listening through headphones.
-
Citations
36 Claims
-
1. An apparatus for binauralizing a set of one or more audio input signals comprising:
-
a binauralizer implementing one or more pairs of binaural filters, one respective pair for each of the audio signal inputs, each pair of binaural filters having a left ear output and a right ear output, each pair of binaural filters representable by a left ear binaural filter and a right ear binaural filter, respectively, each pair of binaural filters further representable by a sum filter and a difference filter related to the left and right ear binaural filters, each filter having a respective impulse response that characterizes the filter, wherein at least one pair of binaural filters is configured to spatialize its respective audio input signal to incorporate a direct response to a listener from a respective virtual speaker location, and to incorporate both early echoes and a reverberant response of a listening room, and wherein for the at least one pair of binaural filters configured to spatialize; the time-frequency characteristics of the sum filter are different than the time-frequency characteristics of the difference filter, with the sum filter reverberation time smaller at all frequencies than each of;
the difference filter reverberation time, the left ear filter reverberation time, and the right ear filter reverberation time; andthe sum filter reverberation time varies more across different frequencies than the respective variation over frequencies of the left ear filter reverberation time and of the right ear filter reverberation time, with the sum filter reverberation time decreasing with increasing frequency, such that the one or more audio input signals filtered by the pair of binaural filters generate output signals that are perceived as spatialized when played through headphones and sound good when played monophonically after a monophonic mix achieved by downmixing or by playing over relatively closely spaced loudspeakers, wherein for the at least one pair of binaural filters, the transition of the sum filter impulse response to its negligible level occurs gradually over time in a frequency dependent manner over an initial time interval of the sum filter impulse response, wherein for the at least one pair of binaural filters, the sum filter decreases in frequency content from being initially full bandwidth towards a low frequency cutoff over the transition time interval. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
-
-
15. A method of binauralizing a set of one or more audio input signals, the method comprising:
-
filtering the set of audio input signals by a binauralizer implementing one or more pairs of binaural filters, one respective pair for each of the audio signal inputs, each pair of binaural filters having a left ear output and a right ear output, each pair of binaural filters representable by a left ear binaural filter and a right ear binaural filter, respectively, each pair of binaural filters further representable by a sum filter and a difference filter related to the left and right ear binaural filters, each filter having a respective impulse response that characterizes the filter, wherein at least one pair of binaural filters is configured to spatialize its respective audio input signal to incorporate a direct response to a listener from a respective virtual speaker location, and to incorporate both early echoes and a reverberant response of a listening room, and wherein for the at least one pair of binaural filters configured to spatialize; the time-frequency characteristics of the sum filter are different than the time-frequency characteristics of the difference filter, with the sum filter reverberation time smaller at all frequencies than each of;
the difference filter reverberation time, the left ear filter reverberation time, and the right ear filter reverberation time; andthe sum filter reverberation time varies more across different frequencies that the respective variation over frequencies of the left ear filter reverberation time and of the right ear filter reverberation time, with the sum filter reverberation time decreasing with increasing frequency, such that the outputs are perceived as spatialized when played through headphones and sound good when played monophonically after a monophonic mix achieved by downmixing or by playing over relatively closely spaced loudspeakers, wherein for the at least one pair of binaural filters, the transition of the sum filter impulse response to its negligible level occurs gradually over time in a frequency dependent manner over an initial time interval of the sum filter impulse response, wherein for the at least one pair of binaural filters, the sum filter decreases in frequency content from being initially full bandwidth towards a low frequency cutoff over the transition time interval. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
-
-
27. A method of processing a pair of signals to generate modified binaural filters, the method comprising:
-
accepting a pair of signals representing the impulse responses of a corresponding pair of to-be-matched binaural filters configured to binauralize an audio signal; processing a sum filter and difference filter representation of the pair of accepted signals by a pair of filters each characterized by a modifying filter that has time varying filter characteristics, the processing forming a sum filter and difference filter representation of a pair of modified signals representing the impulse responses of a corresponding pair of modified binaural filters, such that the modified binaural filters are configured to binauralize an audio signal and further have the property of low perceived reverberation in a monophonic mix down, and minimal impact on the binaural filters over headphones wherein modified binaural filters are characterizable by a modified sum filter and a modified difference filters, and wherein the time varying filters are configured such that; modified binaural filters impulse responses include a direct part defined by head related transfer functions for a listener listening to a virtual speaker at a predefined location; the modified sum filter has a reduced level and a shorter reverberation time compared to the modified difference filter, and there is a smooth transition from the direct part of the impulse response of the sum filter to the negligible response part of the sum filter, with smooth transition being frequency selective over time. - View Dependent Claims (28, 29, 30, 31)
-
-
32. A method of processing a left ear signal and right ear signal to generate modified binaural filters, the method comprising:
-
accepting a left ear signal and right ear signal representing the impulse responses of corresponding left ear and right ear binaural filters configured to binauralize an audio signal; shuffling the left ear signal and right ear signal to form a sum signal proportional to the sum of the left and right ear signals and a difference signal proportional to difference between the left ear signal and the right ear signal; filtering the sum signal by a sum filter that has time varying filter characteristics, the filtering forming a filtered sum signal; processing the difference signal by a difference filter that is characterized by the sum filter, the processing forming a filtered difference signal; unshuffling the filtered sum signal and the filtered difference signal to form a modified left ear signal and modified right ear signal representing the impulse responses of corresponding left ear and right ear modified binaural filters, wherein the modified binaural filters are configured to binauralize an audio signal, are each representable by a respective modified sum filter and a respective modified difference filter, and further have a left ear output and a right ear output, each pair of binaural filters representable by a left ear binaural filter and a right ear binaural filter, respectively, each filter having a respective impulse response that characterizes the filter, wherein at least one pair of binaural filters is configured to spatialize its respective audio input signal to incorporate a direct response to a listener from a respective virtual speaker location, and to incorporate both early echoes and a reverberant response of a listening room, and wherein for the at least one pair of binaural filters; the time-frequency characteristics of the sum filter are different than the time-frequency characteristics of the difference filter, with the sum filter reverberation time smaller at all frequencies than each of;
the difference filter reverberation time, the left ear filter reverberation time, and the right ear filter reverberation time; andthe sum filter reverberation time varies more across different frequencies than the respective variation over frequencies of the left ear filter reverberation time and of the right ear filter reverberation time, with the sum filter reverberation time decreasing with increasing frequency, such that the one or more audio input signals filtered by the pair of binaural filters generate output signals that are perceived as spatialized when played through headphones and sound good when played monophonically after a monophonic mix achieved by downmixing or by playing over relatively closely spaced loudspeakers, wherein for the at least one pair of binaural filters, the transition of the sum filter impulse response to its negligible level occurs gradually over time in a frequency dependent manner over an initial time interval of the sum filter impulse response, wherein for the at least one pair of binaural filters, the sum filter decreases in frequency content from being initially full bandwidth towards a low frequency cutoff over the transition time interval. - View Dependent Claims (33)
-
-
34. A non-transitory computer readable storage medium configured with instructions that when executed by at least one processor of a processing system causes carrying out a method of binauralizing a set of one or more audio input signals, the method comprising:
-
filtering the set of audio input signals by a binauralizer implementing one or more pairs of binaural filters, one respective pair for each of the audio signal inputs, each pair of binaural filters having a left ear output and a right ear output, each pair of binaural filters representable by a left ear binaural filter and a right ear binaural filter, respectively, each pair of binaural filters further representable by a sum filter and a difference filter related to the left and right ear binaural filters, each filter having a respective impulse response that characterizes the filter, wherein at least one pair of binaural filters is configured to spatialize its respective audio input signal to incorporate a direct response to a listener from a respective virtual speaker location, and to incorporate both early echoes and a reverberant response of a listening room, and wherein for the at least one pair of binaural filters; the time-frequency characteristics of the sum filter are different than the time-frequency characteristics of the difference filter, with the sum filter reverberation time smaller at all frequencies than each of;
the difference filter reverberation time, the left ear filter reverberation time, and the right ear filter reverberation time; andthe sum filter reverberation time varies more across different frequencies that the respective variation over frequencies of the left ear filter reverberation time and of the right ear filter reverberation time, with the sum filter reverberation time decreasing with increasing frequency, such that the outputs are perceived as spatialized when played through headphones and sound good when played monophonically after a monophonic mix achieved by downmixing or by playing over relatively closely spaced loudspeakers, wherein for the at least one pair of binaural filters, the transition of the sum filter impulse response to its negligible level occurs gradually over time in a frequency dependent manner over an initial time interval of the sum filter impulse response, wherein for the at least one pair of binaural filters, the sum filter decreases in frequency content from being initially full bandwidth towards a low frequency cutoff over the transition time interval.
-
-
35. A non-transitory computer readable storage medium configured with instructions that when executed by at least one processor of a processing system causes carrying out a method of processing a pair of signals to generate modified binaural filters, the method comprising:
-
accepting a pair of signals representing the impulse responses of a corresponding pair of to-be-matched binaural filters configured to binauralize an audio signal; processing a sum filter and difference filter representation of the pair of accepted signals by a pair of filters each characterized by a modifying filter that has time varying filter characteristics, the processing forming a sum filter and difference filter representation of a pair of modified signals representing the impulse responses of a corresponding pair of modified binaural filters, such that the modified binaural filters are configured to binauralize an audio signal and further have the property of low perceived reverberation in a monophonic mix down, and minimal impact on the binaural filters over headphones wherein modified binaural filters are characterizable by a modified sum filter and a modified difference filters, and wherein the time varying filters are configured such that; modified binaural filters impulse responses include a direct part defined by head related transfer functions for a listener listening to a virtual speaker at a predefined location; the modified sum filter has a reduced level and a shorter reverberation time compared to the modified difference filter, and there is a smooth transition from the direct part of the impulse response of the sum filter to the negligible response part of the sum filter, with smooth transition being frequency selective over time.
-
-
36. A non-transitory computer readable storage medium configured with instructions that when executed by at least one processor of a processing system causes carrying out a method of processing a left ear signal and right ear signal to generate modified binaural filters, the method comprising:
-
accepting a left ear signal and right ear signal representing the impulse responses of corresponding left ear and right ear binaural filters configured to binauralize an audio signal; shuffling the left ear signal and right ear signal to form a sum signal proportional to the sum of the left and right ear signals and a difference signal proportional to difference between the left ear signal and the right ear signal; filtering the sum signal by a sum filter that has time varying filter characteristics, the filtering forming a filtered sum signal; processing the difference signal by a difference filter that is characterized by the sum filter, the processing forming a filtered difference signal; unshuffling the filtered sum signal and the filtered difference signal to form a modified left ear signal and modified right ear signal representing the impulse responses of corresponding left ear and right ear modified binaural filters, wherein the modified binaural filters are configured to binauralize an audio signal, are each representable by a respective modified sum filter and a respective modified difference filter, and further have a left ear output and a right ear output, each pair of binaural filters representable by a left ear binaural filter and a right ear binaural filter, respectively, each filter having a respective impulse response that characterizes the filter, wherein at least one pair of binaural filters is configured to spatialize its respective audio input signal to incorporate a direct response to a listener from a respective virtual speaker location, and to incorporate both early echoes and a reverberant response of a listening room, and wherein for the at least one pair of binaural filters; the time-frequency characteristics of the sum filter are different than the time-frequency characteristics of the difference filter, with the sum filter reverberation time smaller at all frequencies than each of;
the difference filter reverberation time, the left ear filter reverberation time, and the right ear filter reverberation time; andthe sum filter reverberation time varies more across different frequencies than the respective variation over frequencies of the left ear filter reverberation time and of the right ear filter reverberation time, with the sum filter reverberation time decreasing with increasing frequency, such that the one or more audio input signals filtered by the pair of binaural filters generate output signals that are perceived as spatialized when played through headphones and sound good when played monophonically after a monophonic mix achieved by downmixing or by playing over relatively closely spaced loudspeakers, wherein for the at least one pair of binaural filters, the transition of the sum filter impulse response to its negligible level occurs gradually over time in a frequency dependent manner over an initial time interval of the sum filter impulse response, wherein for the at least one pair of binaural filters, the sum filter decreases in frequency content from being initially full bandwidth towards a low frequency cutoff over the transition time interval.
-
Specification