Prompt Recorder

Record audio from your microphone and download a G.711 μ-law WAV file ready for IVR and IVA prompt uploads. Everything runs in your browser — your audio never leaves your device.

Ready to Record

Click the button below to start recording from your microphone.

Your audio is processed entirely in your browser. Nothing is uploaded to any server.

About the Prompt Recorder

The Prompt Recorder captures audio from your microphone and encodes it as a G.711 μ-law WAV file — the standard format required by most IVR and IVA telephony platforms, including Five9, Avaya, Genesys, and Cisco.

What is G.711 μ-law?

G.711 is the ITU-T standard codec used in PSTN telephone calls. The μ-law variant (used in North America and Japan) encodes 16-bit PCM audio into 8-bit samples at 8,000 Hz using logarithmic compression. This gives an effective dynamic range comparable to 12-bit linear PCM while occupying only 8 kbps of bandwidth — ideal for telephone-quality voice prompts.

Why not just record a regular WAV?

Most telephony platforms require prompts in a specific format: mono, 8 kHz sample rate, 8-bit μ-law encoding. Uploading a standard 44.1 kHz stereo WAV will either be rejected outright or converted automatically — sometimes with quality loss or incorrect loudness. The Prompt Recorder outputs the exact format your platform expects.

How does the pipeline work?

  • Audio is captured via the browser's MediaRecorder API.
  • On stop, the raw audio is decoded using the Web Audio API (AudioContext.decodeAudioData).
  • All channels are mixed down to mono by averaging.
  • The signal is resampled from the device's native rate to 8,000 Hz using linear interpolation.
  • Each sample is encoded with the ITU-T G.711 μ-law algorithm (pure JavaScript, no libraries).
  • A WAV container is written in memory with format code 0x0007, 1 channel, 8 kHz, 8-bit depth.

Is my audio private?

Yes. All recording, resampling, and encoding happens entirely in your browser using the Web Audio API. No audio data is transmitted to any server. The download is generated locally as an in-memory Blob.