Dubbing deck · supply reel · take-up reel · VU
Video to Audio Converter
Load a video, press Dub, and the deck copies its soundtrack onto tape: the reels turn, the meters swing, the counter runs. When it stops, take the MP3 or WAV. Nothing is uploaded; the whole machine runs in your browser.
The soundtrack, off the picture
A video file is a container with a picture track and a sound track laid side by side. Extracting the audio is a dub: the deck plays the sound track and records it onto a new tape, leaving the picture behind. This page does that with the browser's own decoder, which reads the audio out of MP4, WebM, MOV and most audio files, and then writes either an MP3 at the bitrate you choose or a lossless WAV.
MP3 or WAV
MP3 is small and plays everywhere; 128 kbps is fine for speech and podcasts, 192 or 320 for music. WAV is the raw signal, about 10 MB a minute in stereo, and the right choice when the audio is going into an editor for more work. The MP3 encoder runs in the page (the open-source lamejs port of LAME), so a long file takes a little while; the counter shows how far the dub has got.
Why a dubbing deck
Before files there were two reel-to-reel machines cabled together: one played, one recorded, and you watched the VU meters to keep the level below the red. The reels here turn with the real progress of the dub and the meters follow the real signal level of the audio being written.
The deck says it cannot read the tape
The browser's decoder did not find an audio track it understands: the video may have no sound, or use a codec browsers do not decode (AC-3 and DTS in MKV files are the usual case). Re-export the video with AAC audio, or try a different browser.
How big a file can it take?
The whole file is decoded into memory as raw audio, roughly 10 MB per minute of stereo. Files up to an hour work on a normal laptop; very long recordings may need to be split first.
Is anything uploaded?
No. Decoding and encoding happen in your browser; the file never leaves your computer.