MP4 to WAV converter

People taking the sound out of a video to work on it somewhere else: a recorded interview going into a DAW to clean up, a phone video’s audio going into a transcription tool, dialogue for a podcast edit, a clip’s sound for a sampler or a game, or an upload form that takes WAV and nothing else. Most already have the video and only need its sound in the format the next program asks for.

The sound in your MP4 was compressed once already, almost always as AAC, when the video was recorded or exported. Turning it into MP3 or a new AAC file compresses it a second time, and each pass throws a little more away. A WAV does not compress at all: the page decodes the AAC into plain samples, the same samples your speakers get when the video plays, and writes them down as they are.

So the WAV sounds exactly like the video. It cannot sound better, because what the AAC encoder removed is gone, but nothing you do to it afterwards (cutting, mixing, a noise filter, another export) starts from a copy of a copy. That is why editors and audio tools ask for WAV.

The price is size. Every sample is stored in full, so a minute of stereo sound at 48,000 Hz takes about 11 MB, seven to ten times what the same minute of AAC uses inside the MP4.

Every WAV this page makes is 16-bit PCM, the format nearly every editor, DAW and transcription tool reads. You choose two things.

• Sample rate: Keep the original (the default) writes the video’s own rate, usually 48,000 or 44,100 Hz, so nothing is resampled. It is the closest copy.
• 48,000 Hz matches video work. Choose it when the WAV goes back into a video editor’s timeline, or into a 48 kHz project in a DAW, so nothing has to resample it on import.
• 44,100 Hz is the CD rate and what most music projects use. Choose it for a music project or a CD; raising a lower rate to it adds no detail.
• 8,000 Hz is for phone systems that want their greetings as 8 kHz mono WAV. Speech stays clear; music sounds like it is coming down a phone line.
• Channels: Keep the original, or Mono to mix stereo into one channel (half the size, and enough for a voice), or Stereo to put a mono phone recording on both channels for a tool that insists on two.

Most MP4s have one sound track. Some have more: a screen recording from OBS with the desktop sound and the microphone kept apart, a second language, or a commentary. A WAV holds one, so when there is a choice the page lists the tracks by name and you pick which to keep. For a recording with the microphone on its own track, that gives you the voice without the system sounds, which is often what an editor or a transcription tool wants.

Do not convert in the hope of better sound. The WAV holds exactly what the MP4’s AAC track decodes to, so a muffled phone recording, background hum or a quiet voice stays as it is, only in a much bigger file. Clean it up in an editor afterwards; the WAV is a good starting point for that, but it does not do it for you.

If the program you are sending it to opens MP4 or M4A, there may be no need for a WAV at all: most video editors and many DAWs read the sound straight out of the video. And if you only want a small audio file to listen to or send, an MP3 is a tenth of the size and fine for that. Keep the MP4 if you may need the picture again.