Audio transcoder using encoder-generated side information to transcode to target bit-rate
First Claim
1. A method of transcoding an audio bitstream from an initially coded bit-rate to a target bit-rate using a computing system that implements an audio transcoder, the computing system including a processing unit and memory, the method comprising:
- receiving the audio bitstream, the audio bitstream containing encoded data that represents audio content of an audio input signal, wherein the audio bitstream also contains encoding parameters generated by an audio encoder when encoding the audio input signal to produce the audio bitstream, wherein at least some of the encoding parameters are derived from the audio input signal, wherein the encoding parameters include rate control parameters that parameterize a quality to quantization step size curve, and wherein the rate control parameters comprise a plurality of anchor points on the quality to quantization step size curve;
with the computing system that implements the audio transcoder, decoding the encoding parameters from the audio bitstream;
with the computing system that implements the audio transcoder, partially decoding the audio content of the audio bitstream to an intermediate decoding stage prior to an inverse frequency transform; and
with the computing system that implements the audio transcoder, re-encoding the partially-decoded audio content, based on the encoding parameters, to produce an output bitstream at the target bit-rate.
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Accused Products
Abstract
An audio encoder encodes side information into a compressed audio bitstream containing encoding parameters used by the encoder for one or more encoding techniques, such as a noise-mask-ratio curve used for rate control. A transcoder uses the encoder generated side information to transcode the audio from the original compressed bitstream having an initial bit-rate into a second bitstream having a new bit-rate. Because the side information is derived from the original audio, the transcoder is able to better maintain audio quality of the transcoding. The side information also allows the transcoder to re-encode from an intermediate decoding/encoding stage for faster and lower complexity transcoding.
81 Citations
23 Claims
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1. A method of transcoding an audio bitstream from an initially coded bit-rate to a target bit-rate using a computing system that implements an audio transcoder, the computing system including a processing unit and memory, the method comprising:
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receiving the audio bitstream, the audio bitstream containing encoded data that represents audio content of an audio input signal, wherein the audio bitstream also contains encoding parameters generated by an audio encoder when encoding the audio input signal to produce the audio bitstream, wherein at least some of the encoding parameters are derived from the audio input signal, wherein the encoding parameters include rate control parameters that parameterize a quality to quantization step size curve, and wherein the rate control parameters comprise a plurality of anchor points on the quality to quantization step size curve; with the computing system that implements the audio transcoder, decoding the encoding parameters from the audio bitstream; with the computing system that implements the audio transcoder, partially decoding the audio content of the audio bitstream to an intermediate decoding stage prior to an inverse frequency transform; and with the computing system that implements the audio transcoder, re-encoding the partially-decoded audio content, based on the encoding parameters, to produce an output bitstream at the target bit-rate. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A computing system that implements an audio transcoder, the computing system comprising:
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a processing unit; memory; and storage media storing computer-executable instructions for causing the computing system to implement the audio transcoder using; an input for receiving an input audio bitstream encoded at an initial bit-rate by an audio encoder, the input audio bitstream containing encoded data that represents audio content of an audio input signal, the input audio bitstream also containing encoding parameters generated by the encoder when encoding the audio input signal to produce the input audio bitstream, wherein at least some of the encoding parameters are derived from the audio input signal, wherein the encoding parameters include rate control parameters that parameterize a quality to quantization step size curve, and wherein the rate control parameters comprise a plurality of anchor points on the quality to quantization step size curve; a partial audio decoder having a plurality of decoding modules and operating to partially decode the encoded data to reconstruct the audio content to an intermediate decoding state; a side information decoder for decoding the encoding parameters from the input audio bitstream; and a partial audio encoder having a plurality of encoding modules and operating to re-encode the audio content from the intermediate decoding state for a target bit-rate based on the encoding parameters to produce an output audio bitstream. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A computer-readable storage media having computer executable instructions stored thereon for causing a computer to perform a method of transcoding an audio bitstream from an initially coded bit-rate to a target bit-rate, the method comprising:
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receiving the audio bitstream, the audio bitstream containing encoded data that represents audio content of an audio input signal, wherein the audio bitstream also contains encoding parameters generated by an audio encoder when encoding the audio input signal to produce the audio bitstream, wherein at least some of the encoding parameters are derived from the audio input signal, and wherein the encoding parameters include rate control parameters that parameterize a quality to quantization step size curve; decoding the encoding parameters from the audio bitstream, wherein the rate control parameters comprise a plurality of anchor points on the quality to quantization step size curve; partially decoding the audio content of the audio bitstream to an intermediate decoding stage prior to an inverse frequency transform; and encoding the partially-decoded audio content based on the encoding parameters to produce an output bitstream at the target bit-rate, wherein the output bitstream omits the encoding parameters. - View Dependent Claims (20, 21, 22, 23)
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Specification