Why editors and transcription tools like WAV
WAV holds PCM audio: the raw sample values, with no compression to unpack. Every audio editor, DAW and video editor imports it without fuss, it can be cut at any sample, and scrubbing through it costs the computer almost nothing.
It also stops quality from wearing away during an edit. Edit compressed audio and export compressed audio again, and each round stacks another generation of losses. Working from WAV leaves the final export as the only lossy step.
That makes it the natural format for cleaning up dialogue, handing a voice track to a mixing engineer, sampling a sound from your own footage, or feeding a transcription service that asks for uncompressed audio.
Producers sampling from video get one more benefit: samplers and DAWs load WAV directly, and stretching or re-pitching plain samples doesn't pile a fresh layer of compression artefacts on top of the ones already in the source.
What WAV can and can't do for quality
The audio in an MP4 is almost always AAC, a lossy format. Extracting it as WAV decodes that AAC into plain samples, the best version of that sound that exists, but not a better one. Hiss, compression artefacts and dull highs in the video stay exactly as they were.
So if you only want to listen to the soundtrack, WAV's size buys you nothing: an MP3 or the Original audio option (an .m4a copy of the AAC track) sounds the same in a fraction of the space. WAV is for audio that will be edited, processed or analysed. And if the problem is a quiet microphone, a bigger format won't help, raise the level after extracting with Normalize Audio.
How big the WAV will be
Uncompressed audio is simple arithmetic: samples per second × bytes per sample × channels. For a typical video soundtrack:
- 48 kHz stereo, 192 KB every second, about 11 MB per minute, roughly 0.7 GB per hour.
- 48 kHz mono, half that, a little under 6 MB per minute. Many phone and lapel-mic recordings are mono, and even then an hour-long lecture comes to around 350 MB: fine for an editor, far too big to email.
- FLAC instead, just as lossless, usually around half to two-thirds of the size, if your browser can create it.
The WAV keeps the video's sample rate and is always 16-bit. Need 44.1 kHz, 24-bit or a mono mix-down? Run the WAV through the audio converter, which offers all three.
A typical workflow
- Extract the WAV from your MP4 here.
- Clean it up in the audio editor: cut mistakes, remove long pauses, fade in and out.
- Check the result against a loudness target with the loudness meter.
- Bring the finished WAV back into your video editor and line it up with the picture.
Only need captions? Auto Subtitles transcribes speech straight from the MP4 on your device, no WAV required.