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US 10,475,460 B2Granted
Audio downmixer operable in prediction or non-prediction mode
AssigneeDolby International AB
InventorsHeiko Purnhagen, Pontus Carlsson, Lars Villemoes
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Abstract
The invention provides methods and apparatuses for encoding a stereo audio signal having a left channel and a right channel. The apparatus includes a prediction coefficient estimator, downmixer, and multiplexer. The downmixer is configured operate either in a prediction mode or a non-prediction mode.
Claims15
An apparatus for encoding a stereo audio signal having a left channel and a right channel, the apparatus comprising:
- a prediction coefficient estimator for generating a prediction coefficient for each of a plurality of frequency bands;
- a downmixer operable in either a prediction mode or a non-prediction mode, the downmixer generating a mid signal and a residual signal;
- and
- a multiplexer for generating an audio bitstream, the audio bitstream including the mid signal, the residual signal, and an encoded representation of the prediction coefficients,
- wherein, when the downmixer operates in the prediction mode, the residual signal represents a difference between a side signal and a predicted version of the side signal, and the downmixer generates the predicted version of the side signal based on the mid signal and the prediction coefficients, and
- wherein, when the downmixer operates in the non-prediction mode, the residual signal represents the side signal, and the downmixer generates the mid signal based on a sum of the left channel and the right channel and generates the residual signal based on a difference between the left channel and the right channel.
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A method for encoding a stereo audio signal having a left channel and a right channel, the method comprising:
- generating a prediction coefficient for each of a plurality of frequency bands;
- generating, with a downmixer operable in either a prediction mode or a non-prediction mode, a mid signal and a residual signal;
- and
- generating an audio bitstream, the audio bitstream including the mid signal, the residual signal, and an encoded representation of the prediction coefficients,
- wherein, when the downmixer operates in the prediction mode, the residual signal represents a difference between a side signal and a predicted version of the side signal, and the downmixer generates the predicted version of the side signal based on the mid signal and the prediction coefficients, and
- wherein, when the downmixer operates in the non-prediction mode, the residual signal represents the side signal, and the downmixer generates the mid signal based on a sum of the left channel and the right channel and generates the residual signal based on a difference between the left channel and the right channel.
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