MP4 to WAV extraction happens entirely on this page: drop your videos anywhere and the audio track is decoded to 16-bit PCM, then saved as a WAV. Nothing uploads, and there is no file cap.
WAV or MP3 from your video?
WAV (this page) when the audio faces editing, precise transcription, or archiving. No compression touches it after the decode. Big files, perfect fidelity to the source. MP3 when it just needs to be small and playable.
FAQ
What's the output spec?
16-bit PCM at the source sample rate, stereo preserved.
An hour-long recording?
Works. Expect a ~600 MB WAV (uncompressed means big) and use a computer.