Comment by ggus

5 days ago

Not sure if it adds anything, but a factoid I know is that CD timing is expressed in minutes, seconds, and frames, where each frame is 1/75th of a second.

I'm not sure but I think this is also the smallest time resolution.

Then each frame is composed of samples, but they seem to be counted in groups of 1/75th os a second anyway.

5 comments

ggus

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kevin_thibedeau  5 days ago

That's only relevant for navigation from the TOC. The samples are always 22.68us apart. That is the finest resolvable timing difference.

  • frumiousirc  4 days ago

    I was also wondering about the inherent resolution for the BPM precision claims.

    Besides the sample period, the total number of samples matter for frequency resolution (aka BPM precision).

    44100 Hz sampling frequency (22.675737 us period) for 216.276 s is 9537772 samples (rounding to nearest integer). This gives frequency samples with a bandsize of 0.0046237213 Hz which is 0.27742328 BPM.

    Any claim of a BPM more precise than about 0.3 BPM is "creative interpretation".

    And this is a minimum precision. Peaks in real-world spectra have width which further reduces the precision of their location.

    Edit to add:

    https://0x0.st/Pos0.png

    This takes my flac rip of the CD and simply uses the full song waveform. This artificially increases frequency precision by a little compared to taking only the time span where beats are occurring.

    • mrgriscom  4 days ago

      This is plainly false though. You're saying beats can't be localized to less than one second of precision (regardless of track length, which already smells suspect). Humans can localize a beat to within 50ms.

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