Method and apparatus for three-dimensional audio display
First Claim
1. A method for positioning of a plurality of audio signals, the method including:
- selecting a set of spatial functions, each having an associated scaling factor;
providing a first set of amplifiers and a second set of amplifiers, the gains of the amplifiers being functions of the scaling factors;
receiving a first audio signal of the plurality of audio signals;
providing a first direction representing the direction of the source of the first audio signal;
adjusting the gains of the first and the second set of amplifiers depending on the first direction;
applying the first set of amplifiers to the first audio signal to produce first encoded signals;
delaying the first audio signal to produce a first delayed audio signal; and
applying the second set of amplifiers to the first delayed audio signal to produce second encoded signals;
providing a third set of amplifiers and a fourth set of amplifiers, the gains of the amplifiers being functions of the scaling factors;
receiving a second audio signal of the plurality of audio signals;
providing a second direction representing the direction of the source of the second audio signal;
adjusting the gains of the third and the fourth set of amplifiers depending on the second direction;
applying the third set of amplifiers to the second audio signal to produce third encoded signals;
delaying the second audio signal to produce a second delayed audio signal;
applying the fourth set of amplifiers to the second delayed audio signal to produce fourth encoded signals;
mixing the first and the third encoded signals or the first and the fourth encoded signals to provide a left-channel audio output;
mixing the second and the fourth encoded signals or the second and the third encoded signals to provide a right-channel audio output, the left-channel audio output excluding the second encoded signal and the right-channel audio output excluding the first encoded signal; and
decoding the encoded signals using filters that are defined based on the spatial functions.
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Accused Products
Abstract
This invention addresses sound recording and mixing methods for 3-D audio rendering of multiple sound sources over headphones or loudspeaker playback systems. Economical techniques are provided, whereby directional panning and mixing of sounds are performed in a multi-channel encoding format which preserves interaural time difference information and does not contain head-related spectral information. Decoders are provided for converting the multi-channel encoded signal into signals for playback over headphones or various loudspeaker arrangements. These decoders ensure faithful reproduction of directional auditory information at the eardrums of the listener and can be adapted to the number and geometrical layout of the loudspeakers and the individual characteristics of the listener. A particular multi-channel encoding format is disclosed, which, in addition to the above advantages, is associated with a practical microphone technique for producing 3-D audio recordings compliant with the decoders described.
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Citations
28 Claims
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1. A method for positioning of a plurality of audio signals, the method including:
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selecting a set of spatial functions, each having an associated scaling factor; providing a first set of amplifiers and a second set of amplifiers, the gains of the amplifiers being functions of the scaling factors; receiving a first audio signal of the plurality of audio signals; providing a first direction representing the direction of the source of the first audio signal; adjusting the gains of the first and the second set of amplifiers depending on the first direction; applying the first set of amplifiers to the first audio signal to produce first encoded signals; delaying the first audio signal to produce a first delayed audio signal; and applying the second set of amplifiers to the first delayed audio signal to produce second encoded signals; providing a third set of amplifiers and a fourth set of amplifiers, the gains of the amplifiers being functions of the scaling factors; receiving a second audio signal of the plurality of audio signals; providing a second direction representing the direction of the source of the second audio signal; adjusting the gains of the third and the fourth set of amplifiers depending on the second direction; applying the third set of amplifiers to the second audio signal to produce third encoded signals; delaying the second audio signal to produce a second delayed audio signal; applying the fourth set of amplifiers to the second delayed audio signal to produce fourth encoded signals; mixing the first and the third encoded signals or the first and the fourth encoded signals to provide a left-channel audio output; mixing the second and the fourth encoded signals or the second and the third encoded signals to provide a right-channel audio output, the left-channel audio output excluding the second encoded signal and the right-channel audio output excluding the first encoded signal; and decoding the encoded signals using filters that are defined based on the spatial functions. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of producing an audio signal from directionally encoded multi-channel audio signals, the method including:
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selecting a set of spatial functions; generating a set of spectral functions based on the spatial functions; receiving a first set of directionally encoded audio signals encoded according to the set of spatial functions, the first set of directionally encoded signals providing an encoded left-channel input; receiving a second of set directionally encoded audio signals encoded according to the set of spatial functions, the second set of directionally encoded signals providing an encoded right-channel input, the encoded left-channel input excluding the second set of directionally encoded signals and the encoded right-channel input excluding the first set of directionally encoded signals; providing a first set of decoding filters defined by the set of spectral functions; providing a second set of decoding filters defined by the set of spectral functions; applying the first set of decoding filters to the first set of directionally encoded audio signals to produce a first set of filtered signals; applying the second set of decoding filters to the second set of directionally encoded audio signals to produce a second set of filtered signals; and providing the first set of filtered signals to a left-channel audio output and providing the second set of filtered signals to a right-channel audio output. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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Specification