“[What to do without] Jedi level design skills”


[ Compute! Magazine ]

We essentially got a 20-minute introduction to audio processing today. Here are the notes, for future reference:

  • Vacuum tubes and linearity
    • Digital design trickery
  • SNR, THD
  • DSPs, [ codecs ], and integrated systems
    • MIPS
    • a SPI bus might be involved
    • coding blocks (preferable for copy-paste-maker solutions) vs VisualStudio-like interface vs assembly
  • [ Fixed ] and [ floating point ] DSPs
    • convolution as an n^2 operation (perhaps too much for a microprocessor)
    • thinking on top of 8bit (voice-recorder) reference designs (open-source audio shield designs?)
  • Stereo codecs
    • 18 bit would be a good starting point, with an aim to get reliable 16 bit audio (keeping 2 extra bits)
    • What’s up with 24/32 bit audio anyway? Mastering, radix points, and processing operations.
  • Maintaining the same phase response for left/right channels
  • Sigma-Delta DSPs
    • MHz sampling -> kHz output
    • Changing registers for tuning the frequency range
    • Oversample to identify transitions -> low pass filter for smoothness (and lots of optimization, and neat feedback)
  • Keeping the analog and digital supplies separate
    • Beware: digital signals transition a lot -> NOISE!
  • Breadboards and general laughter
    • antennae

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