WAV holds uncompressed sound: every audio editor, transcription program and sampler opens it, and editing it adds no further compression loss. Converting an MP4 to WAV extracts the sound of the video for that kind of work.
How to convert MP4 to WAV
- Upload the MP4 (or another video; up to 2 GB and 4 hours).
- Choose Save as: WAV.
- Download the WAV file.
What you get
- PCM, 16-bit, at the video's own sample rate (usually 44.1 or 48 kHz) and channels (mono, stereo or surround).
- 24-bit when the video already has 24-bit lossless sound (for example PCM in a MOV from a camera or recorder): the extra detail is kept.
- Unchanged when the video's sound is already PCM that WAV can hold: it is copied as it is.
Size
Uncompressed sound is large: about 10 MB per minute for 16-bit stereo at 44.1 kHz, and 4 hours of sound would be over 2 GB. For long recordings, FLAC keeps exactly the same sound in roughly half the space, and most editors open it too.
About quality
The sound of an MP4 is almost always AAC, a compressed format. WAV stores it exactly as decoded, so no further quality is lost, but detail removed by the original compression can't come back. The result mentions this; it is expected and no reason for concern when the goal is editing.
Tips
- Trim the video first if you only need part of the sound.
- The title and artist tags are kept where WAV can hold them; the video's location and date are not copied.
More about what this tool reads and writes: Extract Audio from Video.