moeru-ai/airi · error · Error

No audio track available in the stream

Error message

No audio track available in the stream

What it means

In the Web branch of the beat-sync detector (packages/stage-shared/src/beat-sync/detector.ts:138), audio is captured via navigator.mediaDevices.getDisplayMedia with echoCancellation/noiseSuppression/autoGainControl disabled. If the returned MediaStream has zero audio tracks, this error is thrown: the user shared a surface but no audio came with it, so there is nothing for the analyser to read.

Solutions

  1. Re-run getDisplayMedia and instruct the user to pick a Screen/Tab surface AND tick the share-audio checkbox
  2. Catch this error and fall back to microphone input via getUserMedia({ audio: true })
  3. Pre-check browser support and surface an explicit 'enable audio sharing' hint in the UI

Example fix

// before
const stream = await navigator.mediaDevices.getDisplayMedia({ audio: { echoCancellation: false }, video: true })
if (stream.getAudioTracks().length === 0) throw new Error('No audio track available in the stream')
// after
let stream = await navigator.mediaDevices.getDisplayMedia({ audio: { echoCancellation: false }, video: true })
if (stream.getAudioTracks().length === 0) {
  stream = await navigator.mediaDevices.getUserMedia({ audio: true }) // mic fallback
}
Defensive patterns

Strategy: fallback

Validate before calling

const stream = await navigator.mediaDevices.getDisplayMedia({ audio: { echoCancellation: false, noiseSuppression: false, autoGainControl: false }, video: true })
if (stream.getAudioTracks().length === 0) {
  // prompt user to retry with audio, or fall back before the detector throws
  stream.getTracks().forEach(t => t.stop())
  stream = await navigator.mediaDevices.getUserMedia({ audio: true })
}

Type guard

const hasAudioTrack = (stream: MediaStream): boolean => stream.getAudioTracks().length > 0

Try / catch

try {
  await startBeatSync({ env: StageEnvironment.Web })
}
catch (error) {
  if (error instanceof Error && error.message === 'No audio track available in the stream') {
    showHint('Tick the share-audio checkbox when picking a screen or tab.')
    return
  }
  throw error
}

Prevention

When it happens

Trigger: User selects a window in the Chrome screen picker (window capture never carries audio), the 'Share tab audio/system audio' checkbox is left unchecked, or a browser/Firefox configuration where display capture exposes no audio track.

Common situations: Music-visualization features that beat-sync from Spotify/YouTube in another tab while the user skips the audio checkbox; kiosk setups; browsers without system-audio capture.

Related errors

AI-assisted analysis of moeru-ai/airi@677329427f (2026-08-18). Data as JSON: /api/errors/bc590306965a3b2f. Report an issue: GitHub.

Appendix: source

Thrown at packages/stage-shared/src/beat-sync/detector.ts:138

  const updateParameters = (params: Partial<AnalyserWorkletParameters>) => {
    analyser?.updateParameters(params)
  }

  const startScreenCapture = async () => start(async (ctx) => {
    switch (options.env) {
      case StageEnvironment.Web: {
        const stream = await navigator.mediaDevices.getDisplayMedia({
          audio: {
            echoCancellation: false,
            noiseSuppression: false,
            autoGainControl: false,
          },
          video: true,
        })

        if (stream.getAudioTracks().length === 0) {
          throw new Error('No audio track available in the stream')
        }

        stream.getAudioTracks().forEach((track) => {
          let stopCalled = false
          track.addEventListener('ended', () => {
            if (stopCalled)
              return
            stopCalled = true
            stop()
          })
        })

        const node = ctx.createMediaStreamSource(stream)
        stopSource = () => {
          stream.getTracks().forEach(track => track.stop())
        }

        return node

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