rodio decodes through symphonia 0.5, which ships no Opus decoder, so raw
.opus sources (audiobookshelf files, and opus from any provider) failed
Decoder::build(). Add OpusSource, a rodio Source that demuxes Ogg with
symphonia own Ogg reader and decodes with libopus (via
symphonia-adapter-libopus, registered into an explicit codec registry), and
route to it by content-sniffing OggS+OpusHead in the player -- the abs stream
URL has no file extension, so the extension hint is not enough. The bundled
libopus builds with cmake/ninja (added to devenv).
Verified end-to-end with ffmpeg mono/stereo opus fixtures including seeking;
11 audio-player tests pass, clippy/fmt clean.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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