Opus Support

[hischampion]

Opus files get handed to the Vorbis decoder and fail. audio/ogg doesn't say which codec is inside, and openFileStream sends all of it to OggVorbisStreamProcessor where VorbisFileBridge returns rc=-132 (OV_ENOTVORBIS).

I've got it working on a branch: https://github.com/hischampion/AudioStreaming/pull/1/changes. CI is green, but I don't have a Mac so it's never run on a device. It's also authored heavily with Claude Opus.

Would you want a PR?

Summary

• OggVorbisStreamProcessor → OggStreamProcessor, driving an injected decoder protocol. The renderer loop and packet accounting are untouched — only decoder references were renamed.
• A sniffer that reads the first Ogg page for OpusHead vs \x01vorbis, since codec can't be known from file hint or Content-Type.
• OpusFileBridge, mirroring VorbisFileBridge, on sbooth/opus-binary-xcframework — same author as the ogg and vorbis packages.

Three commits: the Opus support, a shared ring buffer, and a couple of CI jobs. The last two are separable.

Tests
20 cases, including:

• sniffer: real Opus and Vorbis files
• sniffer: multi-segment first page, where the lacing table shifts the payload
• sniffer: Ogg FLAC, Speex and non-Ogg all report unsupported
• sniffer: truncated input asks for more bytes instead of guessing
• bridge: mono and stereo decode to the right rate, channels and length
• bridge: stereo fixture is 440 Hz left / 660 Hz right, so a broken deinterleave reads as the wrong frequency rather than as silence
• bridge: a fixture declaring input_sample_rate: 44100 still decodes at 48 kHz (the Opus pitch-shift trap)
• bridge: recovers from a failed open when the header is larger than the 16 KB open threshold
• bridge: Vorbis streams and junk are rejected

Manually ran the bridge against libopusfile and output is bit-identical to ffmpeg's. Valgrind is clean.

Goal
The motive here is to support a certain streaming app for the self-hosted music server Navidrome, which defaults to opus when transcoding.