Learn › Media & Compression
Audio Codecs
MP3, AAC, Opus — perceptual masking as a way of discarding
01
·Audio Codecs·★ MEMBER·8 min read
Audio Compression from Scratch — The Art of Discarding What You Cannot Hear
How does MP3 sound 'the same' at less than a tenth of the size? We build up audio codecs from zero — auditory masking, the MDCT, and bit allocation — and finish with when to reach for MP3, AAC, or Opus.
02
·Audio Codecs·★ MEMBER·10 min read
MP3 and Psychoacoustics — The Science of Sounds You Cannot Hear
MP3 does not throw away sounds that aren't there — it throws away sounds that are there and inaudible. This piece works through the three holes in human hearing (absolute threshold, simultaneous masking, temporal masking) down to the equations, then follows SMR into bit allocation, the encoder's two nested loops, and the bit reservoir.
03
·Audio Codecs·★ MEMBER·PAPER·11 min read
Why Opus Won — The Design of a Modern Audio Codec
Audio codecs used to split cleanly into speech codecs and music codecs. Opus ended the split by stacking two engines, SILK and CELT, inside a single bitstream. This piece works up from zero: how linear prediction and the MDCT divide the spectrum between them, why CELT refuses to let band energy collapse, what actually sets a codec's latency, and the technical and institutional reasons Opus became WebRTC's mandatory codec.
04
·Audio Codecs·★ MEMBER·PAPER·12 min read
Neural Audio Codecs — EnCodec and the Foundation Under Speech LLMs
MP3 and Opus were hand-designed around what the ear cannot hear. Neural audio codecs learn the coding itself and turn sound into a finite alphabet of integers. From vector quantization to residual VQ, EnCodec's bitrate arithmetic, and why VALL-E and AudioLM are built on top of it — starting from zero.