3 ms·
"So you're recording on a record. How fast does the record spin? Do you want a constant angular velocity or constant linear velocity? At what angle does the sty
by keithpeter 14y ago
"So you're recording on a record. How fast does the record spin? Do you want a constant angular velocity or constant linear velocity? At what angle does the stylus move? Is there equalization that must be removed afterwards? Is there some kind of modulation?"
Fair points. A possible elaboration is that analogue encoding is discoverable from the medium. If we know that a recording is of a voice, then we can recover the amplitude signal and speed up/slow down until it sounds right or until the spectrum matches what we know of the source. Digital encoding is not discoverable from the medium in quite the same way...
- klodolph 14y agoWell, no, it's not that easy. You can't always just speed things up or slow them down. For example, try to extract audio from a CD-4 / Quadradisc record. Two of the channels are modulated with a 30 kHz carrier using something called FM-PM-SSBFM, and they won't be audible unless you demodulate them properly. You won't get anything resembling music unless you know exactly what you're doing. By comparison, I've recovered audio from undocumented proprietary PCM-based formats from video games made in the 90s. It was no problem. So I think the distinction between analogue and digital is not as important as the distinction between simple formats (mono/stereo records, linear PCM) and complex formats (FM-PM-SSBFM, MP3).