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Comment by eggsby | Hacker News Reader

There is a cut and dry relationship between bitrate and audio fidelity. You simply cannot encode higher frequency audio in lower bitrate samples.

https://en.wikipedia.org/wiki/Nyquist%E2%80%93Shannon_sampli...

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That's irrelevant because human ears aren't spectrum analyzers. Audio compression codecs exploit weakness in human perception[1] to discard data with minimal loss of subjective audio quality.

[1] https://en.wikipedia.org/wiki/Psychoacoustics

Too bad we have that pesky brain in the way. Human perception isn't just a matter of signal processing theory.

Nyquist is about sample rate and frequency, not bitrate and frequency.

Edit: Clearly there is generally a relationship between bitrate and quality, but for compressed audio it is far from "cut and dry".

Bitrate is just samplerate * bit depth. For 44100 and 32 bit float you have 1411200 bit per second.

That's only true for uncompressed audio.

Yes, but for most codecs, bitrate is variable. For the parts where the higher frequencies are present the codec is free to bump up the bitrate and it can also scale it down for silent parts or parts with low frequencies only.

Sure, if it were encoded at a variable rate. But then it wouldn’t be 320kbps CBR. Normally when I see people refer to 320kbps audio they literally mean constant bitrate. If it’s variable then for LAME mp3 people would specify V0 or V2. At least that’s the taxonomy that I absorbed when I was active on what.cd

Edit: you have edited your comment to remove mention of 320kbps so my comment is now moot :)

Yes, but afaik Spotify uses Ogg Vorbis, which is inherently VBR. https://en.wikipedia.org/wiki/Vorbis

Sorry. I removed the part about 320 kbps being an average, since I realized it was wrong, but you were faster :D.

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