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SYSTEM AND METHOD FOR ADDING AN INAUDIBLE CODE TO AN AUDIO SIGNAL AND METHOD AND APPARATUS FOR READING A CODE SIGNAL FROM AN AUDIO SIGNAL
SYSTEM AND METHOD FOR ADDING AN INAUDIBLE CODE TO AN AUDIO SIGNAL AND METHOD AND APPARATUS FOR READING A CODE SIGNAL FROM AN AUDIO SIGNAL
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机译:用于将音频代码添加到音频信号的系统和方法以及用于从音频信号中读取代码信号的方法和装置
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摘要
An encoder includes a sampler that samples an audio signal and that generates from the samples a plurality of short blocks of sampled audio. Each of the short blocks has a duration less than a minimum audibly perceivable signal delay. A processor combines the plurality of short blocks into a long block. The long block is transformed into a frequency domain signal having a plurality of independently modulatable frequency indices. The frequency difference between adjacent indices is determined by the minimum duration and the sampling rate of the sampler. A neighborhood of frequency indices is selected so that the frequency difference between a lowest index and a highest index within the neighborhood is less than a predetermined value. Two or more of the indices are modulated in the neighborhood so as to make a selected one of the indices an extremum while keeping the total energy of the neighborhood constant. A plurality of frequency bands are so coded. A decoder decides that a bit or bits have been received if, in a majority of the frequency bands, the decoder detects a modulated index.
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