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Voice chat

CrowdyJS sends proximity voice the same way it sends webcam video: opaque packets over the GraphQL UDP proxy (or the binary relay), fanned out by chunk + distance. There is no WebRTC session and the platform never decodes the audio. Your game captures, encodes, and plays.

Permission​

sendAudioPacket needs use_voice_chat on the sender's access tier and on the grid under the target chunk. A new app's default tier already carries this key. A send without it is refused with UNAUTHORIZED (error code 7) on the genericError / errors lane.

Sending: udp.sendAudioPacket​

The recommended browser payload (used by The Construct and Blocks with Friends):

  • G.711 µ-law
  • 8 kHz mono
  • ~60 ms frames (480 bytes — well inside the spatial payload budget)
  • wrapping sequenceNumber (uint8) so receivers drop late or duplicate frames
await game.udp.sendAudioPacket({
  appId,
  chunk: session.self.chunk!,
  uuid: session.self.uuid,
  audioData: base64MuLawFrame, // 480 bytes µ-law
  distance: 1,
  sequenceNumber: (seq = (seq + 1) & 0xff),
});

There is no success echo. Prefer the fire-and-forget send; a refusal arrives as a correlated GenericErrorResponse. Enable realtime.binaryTransport: true when gameClientBootstrap.binaryRelayEnabled is true so voice (and video) does not ride one GraphQL mutation per frame.

Receiving: handlers.audio​

game.udp.subscribe({
  audio: (n) => {
    if (n.uuid === session.self.uuid) return;
    playMuLaw(n.uuid, decodeBase64(n.audioData), n.sequenceNumber);
  },
  actorLeft: (n) => forgetSpeaker(n.uuid),
}, appId);

Drop duplicate or stale sequenceNumbers (an 8-bit wrap; a long gap is a new utterance). Release per-speaker Web Audio nodes on actorLeft.

References​

  • The Construct starter: src/platform/media/VoiceService.ts
  • Blocks with Friends: src/audio/VoiceChat.ts
  • Unreal: Voice chat
  • Webcam video — the same spatial fan-out, for JPEG/WebP frames