[David Elner (delner)]

Based on #2657

To provide more efficient, out-of-the-box encoding of audio, this adds opus and ogg plugins as middleware.

What it does

By default, voice recordings upload as standard Ogg Opus files instead of raw PCM.

Install the package to activate:

npm install @braintrust/audio

Encoder settings are optional and declarative:

import { configureInstrumentation } from "braintrust/instrumentation";

configureInstrumentation({
  integrations: {
    livekit: {
      audio: {
        codec: { name: "opus", options: { bitrate: 32_000 } },
        container: { name: "ogg" },
      },
    },
  },
});

• Optional. braintrust doesn't depend on this package. Without it, recordings fall back to raw PCM, with a warning.
• Per integration. Each integration owns its defaults: LiveKit records Opus in Ogg.
• Opt out in code. Set codec: { name: "pcm" } to always record raw PCM.

How it works

livekit.audio ─► encoding config ─► loads @braintrust/audio ─► createStack(config) ─► AudioRecorder
                  (+ defaults)       (Node only, once)           opus → ogg

• Opus encodes speech with libopus (WebAssembly, via @audio/encode-opus) 20 ms at a time, pausing for the event loop every second of audio, so the agent stays responsive.
• Ogg wraps the packets in a standard file with no extra dependencies. The file plays back at exactly the recorded length.
• Declarative config, middleware underneath. The SDK turns codec and container into the internal middleware pipeline; users never write middleware.

Performance

Measured on one 44-second recording segment: about 0.4 s of CPU in total, with the longest pause to the event loop around 10 ms, and 4 MB of PCM uploaded as 344 KB.