• CrayonRosary@lemmy.world
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    7 months ago

    I can’t hear anything above 20 kHz, and neither can most people. CD audio is passed through a 20 kHz lowpass filter. It is then sampled at 44 kHz. Due to the Nyquist Shannon Spamling Theorum, when sound is digitally sampled at just above twice the rate of the source audio, converting it back to analog perfectly reproduces the original waveform. And I do mean perfectly. The exact same waveform. (The extra 4 kHz is to prevent artifacts in frequencies very close to 20 kHz.)

    Therefore CD audio is perfect unless you think you can hear above 20 kHz. (Spoiler: you can’t) There are a few good YouTube videos on this topic, and the best ones are very mathy.

    Is there something I’m missing? Do I need to educate myself some more?

    • tjsauce@lemmy.world
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      7 months ago

      You are correct, CDs can reproduce the human audio spectrum perfectly, IF AND ONLY IF certain rules are followed, and I think that’s why earlier CDs sounded weird. For example: how good were low pass filters when digital sound first arrived?

    • renzev@lemmy.world
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      7 months ago

      I don’t know shit about fuck, but you explanation seems correct.

      I do remember hearing that precisely because of the limitations of vinyl compared to CD, music is mastered differently for each medium. So the CD master of a certain song might be more compressed (dynamic compression, not digital compression) to make it sound “louder”, while the vinyl release has a wider dynamic range. So some people might prefer the vinyl version because it actually does sound different to the CD version.

      Keep in mind tho, I might be spreading misinformation here.

      • CrayonRosary@lemmy.world
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        7 months ago

        The loudness wars were definitely a thing; you are correct. But that was a choice and not a limitation of the medium. Plenty of CDs were not produced that way. But that’s not what the OC was talking about. They were talking about down sampling, not dynamic range compression.