# Opus Transport Testing

Lesavka does not use SIP, RTP, or SIPp for upstream microphone media. Upstream
audio is bundled with webcam video in `UpstreamMediaBundle`, and the launcher can
select either compressed `Opus` or raw `S16LE` PCM.

The Opus profile protects the production migration seam:

- The protobuf schema can explicitly label `AudioPacket` payloads as `PCM_S16LE`
  or `OPUS`.
- Legacy or unstamped audio still normalizes to `PCM_S16LE`.
- Client microphone packets stamp PCM metadata before optional Opus encoding.
- Bundled media carries batch-level audio encoding metadata beside video.
- The server decodes Opus back to raw PCM before handing audio to the UAC sink.
- If Opus encode/decode is unavailable, Lesavka falls back to or drops safely
  instead of treating compressed bytes as PCM.
- Performance tests compare the 20 ms Opus budget against raw PCM byte pressure.

Current Opus model:

- sample rate: `48000`
- channels: `2`
- frame duration: `20000us`
- target bitrate: `64000bps`
- expected payload: about `160 bytes` per 20 ms frame

The current route is:

`raw mic capture -> optional webrtcdsp -> opusenc -> gRPC bundle -> opusdec -> raw UAC`

PCM remains available as:

`raw mic capture -> optional webrtcdsp -> gRPC bundle -> raw UAC`

Any recalibration should record both the upstream video codec (`HEVC`/`MJPEG`)
and upstream audio codec (`Opus`/`PCM`) so old PCM baselines stay distinguishable.
Server calibration profiles use `camera+audio` names such as `hevc+pcm` and
`hevc+opus`. The PCM maps are the known-good factory values; the Opus maps start
as a separate namespace and should be replaced only after Theia/RCT calibration.