Audio JS package

Early development notice: @braintrust/audio is in early development (alpha). Expect backwards-incompatible changes between releases until v1.0.

The @braintrust/audio package compresses voice recordings that Braintrust instrumentation captures, such as LiveKit Agents call audio. With the package installed, recordings upload as Opus audio in Ogg files (audio/ogg) instead of raw PCM.

Installation

We strongly recommend using @braintrust/audio to compress recordings and reduce upload size. Install the package alongside braintrust v3.41.0 or later. It requires Node.js 20 or later.

npm install @braintrust/audio

pnpm add @braintrust/audio

Quick start

Braintrust finds and loads @braintrust/audio from node_modules automatically, so you don’t import it in your code. Once you turn on LiveKit Agents audio recording with BRAINTRUST_CAPTURE_USER_AUDIO_ATTACHMENTS or BRAINTRUST_CAPTURE_AGENT_AUDIO_ATTACHMENTS, recordings upload as Opus audio in Ogg files. If you deploy a bundle without node_modules, import the package in your app so your bundler includes it:

import "@braintrust/audio";

If the package is missing, fails to load, doesn’t match your braintrust version, or the audio options contain an unsupported value, recordings upload as raw PCM and Braintrust logs a warning that explains why.

Configuration

To change the encoding, pass audio options for the livekit integration to configureInstrumentation() from braintrust/instrumentation. Call it in a separate file, and load that file before the hook.

configure.mjs

import { configureInstrumentation } from "braintrust/instrumentation";

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

Setting	Default	Description
`codec.name`	`"opus"`	`"opus"`, or `"pcm"` to always record raw PCM, even when `@braintrust/audio` is installed.
`codec.options.bitrate`	`64000`	Target bitrate in whole bits per second, from `500` to `512000`.
`codec.options.complexity`	`5`	Encoder effort, from `0` (fastest) to `10`.
`codec.options.application`	`"audio"`	Encoder tuning: `"audio"`, `"voip"` (favors speech), or `"lowdelay"`.
`container.name`	`"ogg"`	File format for Opus audio. `"ogg"` is the only value.

See Compress recordings for how these settings apply to LiveKit Agents.

Source code

For the complete source code, visit the Braintrust JavaScript SDK repository.

Use the SDK

Features

Reference

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