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US 10,770,088 B2Granted
Adaptive audio decoder system, method and article
AssigneeImmersion Networks, Inc.
InventorsJames D. Johnston, Stephen White
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Abstract
A decoder generates decoded signals based on quantized signals. The decoder includes an inverse quantizer and a predictor circuit. The quantized signals are generated in an encoder by low-pass filtering an input signal and encoding the filtered signal using adaptive differential pulse code modulation. The predictor circuit has filter coefficients based on a frequency response of the low-pass filter used to filter the input signal.
Claims36
An apparatus, comprising:
- a decoder configured to generate decoded signals based on quantized signals and generating a prediction signal, the decoder including:
- a feedback loop including:
- an inverse quantizer configured to receive a quantized signal from a variable rate adaptive quantizer;
- and
- a predictor circuit;
- and
- a low-pass filter having a stop band with a bandwidth selected as a function of a sampling rate, wherein the stop band bandwidth is at least 31% of half of the sampling rate
- an adder configured to receive an output of the decoder and a modified low-pass filter output;
- wherein the low-pass filter and the predictor circuit are coupled and the predictor circuit is configured to provide a predetermined prediction gain for the input signal as a function of the stop band bandwidth of the low-pass filter.
6 more elements
A method, comprising:
- decoding an encoded signal using a feedback loop, the decoding including:
- inverse quantizing a quantized signal using an inverse quantizer that is configured to receive the quantized signal from a variable rate adaptive quantizer;
- generating a prediction signal based on the quantized signal using a prediction circuit;
- and
- filtering the decoded signal using a low-pass filter having a stop band having a bandwidth of at least 31% of one half of a sampling rate wherein the predictor circuit has determined control parameters and filter coefficients based on a frequency response of the low-pass filter.
2 more elements
A non-transitory computer-readable medium having contents which configure signal processing circuitry to perform a method, the method comprising:
- decoding an encoded signal using feedback, the decoding including:
- inverse quantizing a quantized signal using an inverse quantizer that is configured to receive the quantized signal from a variable rate adaptive quantizer;
- and
- generating a prediction signal based on the quantized signal;
- and
- filtering the decoded signal, the filtering including low-pass filtering using a stop band having a bandwidth of at least 31% of one half of a sampling rate, wherein the generating the prediction signal includes using determined control parameters based on a frequency response of the low-pass filtering and the fixed filter coefficients of the low-pass filtering.
3 more elements
A system, comprising:
- a decoder configured to generate decoded signals based on quantized signals and generating a prediction signal, the decoder including:
- an inverse quantizer configured to receive a quantized signal from a variable rate adaptive quantizer;
- and
- a predictor circuit having fixed filter coefficients;
- and
- an encoder including a low-pass filter having a stop band having a bandwidth of at least 31% of one half of a sampling rate and configured to filter a signal to be encoded by the encoder, the predictor circuit of the decoder having determined control parameters based on a frequency response of the low-pass filter of the encoder, wherein the low-pass filter and the predictor circuit are coupled and the predictor circuit is configured to provide a predetermined prediction gain for the input signal as a function of the stop band bandwidth of the low-pass filter.
3 more elements
A system, comprising:
- a decoder configured to generate decoded signals based on quantized signals and generating a prediction signal, the decoder including:
- an inverse quantizer configured to receive a quantized signal from a variable rate adaptive quantizer;
- and
- a predictor circuit;
- and
- an output filter coupled to the decoder and having determined control parameters to limit a bandwidth of an output of the decoder to less than seventy-five percent of the available bandwidth based on a fixed sampling frequency of the quantized signals that is greater than 48 kHz, wherein the predictor circuit has determined control parameters based on a frequency response of the output filter and a stop band having a bandwidth of at least 31% of one half of a sampling rate of a low-pass filter, wherein low-pass filter and the predictor circuit are coupled and the predictor circuit is configured to provide a predetermined prediction gain for the input signal as a function of the stop band bandwidth of the low-pass filter.
3 more elements
A system, comprising:
- a decoder configured to generate decoded signals based on the quantized signals and generating a prediction signal, the decoder including:
- an inverse quantizer configured to receive a quantized signal from a variable rate adaptive quantizer;
- and
- a predictor circuit having fixed filter coefficients;
- and
- an output filter configured to filter an output of the decoder, wherein the predictor circuit has determined control parameters based on a frequency response of an encoder low-pass filter having a stop band with a bandwidth of at least 31% of one half of a sampling rate.
3 more elements
Dependencies are inferred from the claim text.