Module codec 

Framing and conversion: esp_audio_codec’s PCM/ADPCM remade, plus WAV headers, plus FLAC through the house rusty_flac behind the flac feature (the one allocating module). Lossy codecs are a measured decision (A4).

Modules

adpcm_ima

IMA ADPCM in the WAV (WAVE_FORMAT_IMA_ADPCM, tag 0x11) block layout: 4:1 compression of 16-bit PCM with a 4-byte header per channel per block.

pcm

Sample-format conversion with fixed, documented rules — the ones ffmpeg’s swresample uses, so the oracle test in rusty_esp_audio-esp can demand byte identity. The conversion lives in rusty_esp_dsp::sample::pcm (moved verbatim in D0, 2026-09-02, with its rule table and its tests); this module keeps the path this crate always had.

wav

RIFF/WAVE headers for PCM, IEEE float and IMA ADPCM, written into and parsed from caller buffers. Enough for a recorder to write a file any player opens, and for a reader to find the data.