Method and apparatus for sample rate pre- and post-processing to achieve maximal coding gain for transform-based audio encoding and decoding
AssigneeAT&T Corp.
InventorJames H. Snyder
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Abstract
The invention relates to a method and apparatus for achieving maximal coding gain for audio transmission. More particularly, at a chosen sample rate and frequency range value, an audio input signal is downsampled to the sample rate, encoded and transmitted at a given bit rate. At the receiving end, the downsampled signal is decoded and upsampled to the original or other suitable sample rate. The upsampled signal is then audibly output. Since resampling ratios using “small” numbers prove to be more computationally efficient, this method and apparatus supports resampling ratios which imply both standard and non-standard sampling ratios in the coded.
Claims24
A method for preparing audio signals for encoding and transmitting in a multi-media communications network, comprising:
- receiving a baseband in-put audio signal;
- downsampling the baseband input audio signal at a first communication device from an original sampling rate to the baseband signal at a predetermined intermediate sampling rate that allows improved signal fidelity when encoded;
- and resampling the donwsampled baseband signal to a predetermined sampling rate for subsequent output.
An apparatus for resampling audio signals and transmitting the audio signals in a multi-media communications network, comprising:
- a first terminal including
- a downsampler that receives a baseband input audio signal and downsamples the baseband input audio signal from an original sampling rate to the baseband signal at a predetermined intermediate sampling rate that allows improved signal fidelity when encoded;
- and
- the second terminal including
- a resampler that resamples the downsampled signal to a predetermined sampling rate for subsequent output.
An apparatus for preparing audio signals for encoding and transmitting in a multimedia communications network, comprising:
- a downsampler that receives a baseband input audio signal and downsamples the baseband input audio signal from an original sampling rate to the baseband signal at a predetermined intermediate sampling rate that allows improved signal fidelity when encoded;
- wherein the downsampler uses computationally efficient small integers for downsampling.
An apparatus for preparing a received downsampled transmission in a multimedia communications network for outputting, comprising:
- a resampler that receives the downsampled signal and resamples the downsampled signal to a predetermined sampling rate;
- wherein the resampler uses computationally efficient small integers for resampling.
Dependencies are inferred from the claim text.