| 摘要 |
A system, including a processor to define opportunities for encoding a watermark into an audio stream having sections, each section, when represented in the frequency domain, including a signal of amplitude against frequency, the processor being operative to, for each one of the sections, identify a fundamental frequency, f being the frequency with the largest amplitude of the signal in the one section, the fundamental frequency f defining harmonic frequencies, each harmonic frequency being at a frequency f/2n or 2fn, n being a positive integer, and define the one section as an opportunity for encoding at least part of the watermark if the amplitude of the signal of the one section is less than a value v for all frequencies in one or more different frequency ranges, each of the different frequency ranges being centered around different ones of the harmonic frequencies. Related apparatus and methods are also described. |
| 主权项 |
1. A system, comprising a processor to define a plurality of opportunities for encoding a watermark into an audio stream, the audio stream having a plurality of sections, each of the sections, when represented in the frequency domain, including a signal of amplitude against frequency, the processor being operative to, for each one of the sections of the audio stream:
identify a fundamental frequency, f, of the one section, the fundamental frequency being the frequency with the largest amplitude of the signal in the one section, the fundamental frequency f defining a plurality of harmonic frequencies, each of the harmonic frequencies being at a frequency f/2n or 2fn, n being a positive integer; and define the one section as an opportunity for encoding at least part of the watermark if the amplitude of the signal of the one section is less than a value v for all frequencies in one or more of a plurality of different frequency ranges, each of the different frequency ranges being centered around different ones of the harmonic frequencies.
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