Video to MP3 Converter

Save the sound of any video as an MP3: a recorded lecture in MKV, a camcorder AVI, an old WMV or FLV, a WebM download or an iPhone MOV. Files the browser can decode itself are converted in seconds; everything else goes through the built-in ffmpeg engine, which understands practically every video format (it is a one-time download of about 30 MB). Nothing is uploaded — the conversion runs on your device.

How to use this tool

1. Choose one or more video files (audio files such as WAV or M4A also work).
2. Pick the MP3 bitrate and whether to keep stereo or save mono.
3. For films with several languages, enter the audio track number; the result lists every track found.
4. Optionally set a start and end time, then press Calculate and download the MP3.

Formula

MP3 size ≈ bitrate (kbps) × 125 × length (seconds) bytes

The audio is decoded to PCM and encoded with LAME, the reference MP3 encoder. Surround sound (5.1 or 7.1) is mixed down to stereo because MP3 holds at most two channels. The file name becomes the MP3's title tag.

Example

A 45-minute MKV lecture with a 5.1 AC-3 soundtrack, converted at 128 kbps in stereo: 128 × 125 × 2,700 = 43,200,000 bytes, about 41 MB. Saved as mono at the same bitrate, speech sounds just as clear.