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US 7,003,119 B1Granted
Matrix surround decoder/virtualizer
AssigneeQSound Labs, Inc.
InventorJohn Eric Arthur
Life of this patent
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Abstract
The inventive mechanism uses several sub-systems to generate outputs from the stereo input signal. A first sub-system synthesizes the phantom center output, which places the monaural center image between the left and right speakers in front of the listener. A second sub-system synthesizes the virtual surround (or rear) output signals, which places the sound images to the sides of the listener. A third sub-system synthesizes the left and right stereo outputs, and expands the locations of the left and right sound images.
Claims9
A system for processing a stereo input signal which includes center information, matrix encoded surround information, and stereo information, the system comprising:
- first circuit for providing a center output having center monaural information, which includes a first summer which combines one channel of the stereo input signal with the other channel of the stereo input signal to form a center combined signal which has the surround information removed;
- second circuit for providing a surround output from the matrix encoded surround information having surround monaural information, which includes a second summer which combines one channel of the stereo input signal with an inverse of the other channel of the stereo input signal to form a surround combined signal which has the center information removed;
- third circuit for providing an expanded stereo output, which includes a first Q-filter which adjusts an amplitude and phase of the surround combined signal on a frequency dependent basis to form a first filtered signal;
- a third summer which combines the center combined signal with one channel of the stereo input signal to form a first signal;
- a fourth summer which combines the center combined signal with the other channel of the stereo input signal to form a second signal;
- a fifth summer which combines an inverse of the surround combined signal with the first signal to form the third signal;
- a sixth summer which combines the surround combined signal with the second signal to form a fourth signal;
- a seventh summer which combines the first filtered signal with the third signal to form the first output signal;
- and
- an eighth summer which combines an inverse of the first filtered signal with the fourth signal to form the second output signal.
7 more elements
A system for processing a stereo input signal which includes center information, matrix encoded surround information, and stereo information, the system comprising:
- means for providing a center output having center monaural information, which includes a first summer which combines one channel of the stereo input signal with the other channel of the stereo input signal to form a center combined signal which has the surround information removed;
- means for providing a surround output from the matrix encoded surround information having surround monaural information, which includes a second summer which combines one channel of the stereo input signal with an inverse of the other channel of the stereo input signal to form a surround combined signal which has the center information removed;
- means for providing an expanded stereo output, which includes a filter which adjusts an amplitude and phase of the surround combined signal on a frequency dependent basis to form a first filtered signal;
- a third summer which combines the center combined signal with one channel of the stereo input signal to form a first signal;
- a fourth summer which combines the center combined signal with the other channel of the stereo input signal to form a second signal;
- a fifth summer which combines an inverse of the surround combined signal with the first signal to form the third signal;
- a sixth summer which combines the surround combined signal with the second signal to form a fourth signal;
- a seventh summer which combines the first filtered signal with the third signal to form the first output signal;
- and
- an eighth summer which combines an inverse of the first filtered signal with the fourth signal to form the second output signal.
7 more elements
A method for processing a stereo input signal which includes center information, matrix encoded surround information, and stereo information, the method comprising:
- operating a first circuit for providing a center output having center monaural information, which includes a first summer which combines one channel of the stereo input signal with the other channel of the stereo input signal to form a center combined signal which has the surround information removed;
- operating a second circuit for providing a surround output from the matrix encoded surround information having surround monaural information, which includes a second summer which combines one channel of the stereo input signal with an inverse of the other channel of the stereo input signal to form a surround combined signal which has the center information removed;
- operating a third circuit for providing an expanded stereo output, which includes a filter which adjusts an amplitude and phase of the surround combined signal on a frequency dependent basis to form a first filtered signal;
- combining the center combined signal with one channel of the stereo input signal to form a first signal;
- combining the center combined signal with the other channel of the stereo input signal to form a second signal;
- combining an inverse of the surround combined signal with the first signal to form the third signal;
- combining the surround combined signal with the second signal to form a fourth signal;
- combining the first filtered signal with the third signal to form the first output signal;
- and
- combining an inverse of the first filtered signal with the fourth signal to form the second output signal.
7 more elements
Dependencies are inferred from the claim text.