Digital Show and Tell

Anyone who is interested in understanding any of the nuts and bolts of digital audio will appreciate this video. Anyone who wants to have any kind of informed opinion about how digital audio sounds, its merits and limitations, should also watch this video. Anyone who thinks that the staircase pattern visible on representations of digital audio somehow mars the sound of 16 bit audio compared to 24 bit audio should watch this video.

It describes sampling, quantisation, dither and the limited bandwidth inherent in digital audio in an entertaining and extraordinarily clear way, using analogue signals, oscilloscopes and frequency analysers. This is a fine way to spend 23 minutes of your time.

(From xiph.org)

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5 Responses to Digital Show and Tell

  1. therationalaudiophile.wordpress.com says:

    Yes, it’s a fine video. There are a lot of audiophiles out there who still believe that the theory is flawed, never mind the practice. They half-understand the theory but haven’t quite grasped the role of the reconstruction filter – it is fairly counter-intuitive.

    “8 bit sound” has entered the language as shorthand for the sound of 1980s microcomputers and their ‘sound chips’, or badly-aliased samples made at low sample rates. I think there are many audiophiles who think that if they turned the volume up on a quiet bit of a CD, it would sound just like that.

  2. Regarding your last sentence, they are kind of right. But only if the quiet section peaks at less than -48dBFS. That would be a shockingly quiet section. (Imagine the same section on vinyl — the surface noise would be unbearable if the volume were turned up compensate for the low output.)

  3. therationalaudiophile.wordpress.com says:

    Hi Stephen

    “Regarding your last sentence, they are kind of right.”

    No, I don’t think they are. “8 bit sound” (as I would understand its use by most people) doesn’t just refer to a (not-too-bad) level of pure noise, but to a whole list of ills that appear when one plays with the basics of digital audio without doing it properly – and people like it as a slightly goofy effect. But if I did 8 bits properly, I would only hear vinyl-level noise mixed with the music – no aliasing, no mushiness. But I wouldn’t blame the average punter for thinking that “16 bit” is just a better version of 1980s microcomputer “8 bit”.

  4. Ah, I misunderstood you. Good point.

    Actually, I might do some experiments with eight bit sound. Post about ten seconds of something nice in 16/44.1, and the same thing in 8/44.1 with no dither, and a couple of different types of dither.

  5. Another thing: a lot of the 80s sounds were not just 8 bits, but also 22.05kHz or even lower frequency sampling.

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