Adding second enhancement layer to CELP based core layer
First Claim
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1. A method of transmitting an input audio signal, the method comprising:
- encoding a first coding error of the input audio signal with a scalable codec having a first enhancement layer;
encoding a second coding error by using a second enhancement layer after the first enhancement layer, encoding the second coding error comprising coding fine spectrum coefficients of the second coding error to produce coded fine spectrum coefficients, and coding a spectral envelope of the second coding error to produce a coded spectral envelope;
transmitting the coded fine spectrum coefficients and the coded spectral envelope;
wherein;
the first coding error and the second coding error are in a same band;
the first coding error represents a distortion of an output of an inner core layer codec; and
the first coding error is a weighted difference between an original reference input and a decoded output of the inner core layer codec; and
the second coding error is a weighted difference between a quantized output of the first enhancement layer and unquantized coefficients of the first coding error.
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Abstract
In an embodiment, a method of transmitting an input audio signal is disclosed. A first coding error of the input audio signal with a scalable codec having a first enhancement layer is encoded, and a second coding error is encoded using a second enhancement layer after the first enhancement layer. Encoding the second coding error includes coding fine spectrum coefficients of the second coding error to produce coded fine spectrum coefficients, and coding a spectral envelope of the second coding error to produce a coded spectral envelope. The coded fine spectrum coefficients and the coded spectral envelope are transmitted.
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Citations
21 Claims
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1. A method of transmitting an input audio signal, the method comprising:
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encoding a first coding error of the input audio signal with a scalable codec having a first enhancement layer; encoding a second coding error by using a second enhancement layer after the first enhancement layer, encoding the second coding error comprising coding fine spectrum coefficients of the second coding error to produce coded fine spectrum coefficients, and coding a spectral envelope of the second coding error to produce a coded spectral envelope; transmitting the coded fine spectrum coefficients and the coded spectral envelope;
wherein;the first coding error and the second coding error are in a same band; the first coding error represents a distortion of an output of an inner core layer codec; and
the first coding error is a weighted difference between an original reference input and a decoded output of the inner core layer codec; andthe second coding error is a weighted difference between a quantized output of the first enhancement layer and unquantized coefficients of the first coding error. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of transmitting an input audio signal, the method comprising:
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encoding a first coding error of the input audio signal with a scalable codec having a first modified discrete cosine transform (MDCT) enhancement layer; determining if a second MDCT enhancement layer is needed; and if the second MDCT enhancement layer is needed based on the determining, encoding a second coding error by using the second MDCT enhancement layer after the first MDCT enhancement layer, wherein the first coding error and the second coding error are in a same band, the first coding error represents a distortion of an output of an inner core layer codec, the first coding error is a weighted difference between an original reference input and a decoded output of the inner core layer codec, the second coding error is a weighted difference between a quantized output of the first MDCT enhancement layer and an unquantized coefficients of the first coding error, and the determining is based on at least one of the following parameters includes relative coding error energy, relative weighted coding error energy, coding error energy relative to other bands, and weighted coding error energy relative to other bands, a pitch gain, a pitch correlation, a voicing ratio representing signal periodicity, a spectral sharpness measuring based on a ratio between an average energy level and a maximum energy level, a spectral tilt measurement in a time domain or a frequency domain, and/or a spectral envelope stability measurement on a relative spectrum energy differences over time. - View Dependent Claims (14, 15, 16, 17)
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18. A system for transmitting an input audio signal, the system comprising:
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a transmitter comprising an audio coder, the audio coder comprising a code-excited linear prediction (CELP) codec, a first modified discrete cosine transform (MDCT) enhancement layer configured to encode a first coding error, and a second MDCT enhancement layer configured to encode a second coding error, encode fine spectrum coefficients of the second coding error, and encode a spectral envelope of the second coding error;
wherein;the first coding error and the second coding error are in a same band; the first coding error represents a distortion of an output of an inner core layer codec; and
the first coding error is a weighted difference between an original reference input and a decoded output of the inner core layer codec; andthe second coding error is a weighted difference between a quantized output of the first MDCT enhancement layer and an unquantized coefficients of the first coding error. - View Dependent Claims (19, 20, 21)
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Specification