How audio extraction works
A video file is a container. Inside it there are separate streams: one for the picture, one or more for sound, sometimes subtitles. To extract audio from a video, the tool reads only the sound stream and writes it into an audio file. The picture is not needed and is dropped, so the result is much smaller than the video.
The whole process runs in your browser with a version of FFmpeg built for the web. Your video is not uploaded anywhere. This is useful for big files: a 2 GB video does not need to go over the internet, and private clips stay on your computer.
Copy or convert?
Most MP4 and MOV files from phones and cameras carry their sound in AAC format. If you choose Original audio (no re-encoding), the tool copies this sound stream without decoding it, for example AAC into an M4A file. That is very fast and keeps exactly the original quality. Choosing MP3 or another format means the sound is converted, which takes a little longer and is a new lossy encoding.
| Output | Quality | When to use |
|---|---|---|
| Original audio (copy) | same as the video | fastest, best quality, plays on most devices |
| MP3 | very good at 192 kbps and above | plays everywhere, old car stereos and players |
| WAV / FLAC | no further loss | editing, transcription, music production |
| OPUS / OGG | good at small sizes | voice recordings, web use |
Supported video files
MP4, MOV, M4V, MKV, WEBM, AVI, FLV, 3GP, WMV, MPEG and others. Screen recordings, phone videos, lecture recordings and exported video projects all work. If a video has more than one audio track, the tool uses the main one.
What people use it for
The extracted file has the same length as the video and starts at the same moment, so it stays in sync if you later put it back into a video editor. If you need only a part, for example one song from a concert video, extract the full sound first and then cut it. Files from screen recorders sometimes have very quiet sound; in that case, use Normalize after extraction.
- Saving the talk from a recorded lecture or meeting to listen to on the go.
- Getting the music or voice-over from your own video project.
- Preparing audio for speech to text transcription.
- Making a ringtone from a clip you filmed, using Ringtone for iPhone after extraction.
For the common MP4 to MP3 job there is also a short dedicated page, MP4 to MP3. If you need the opposite, turning audio into a video with a picture, use Audio to Video.
Please extract audio only from videos you made or have the right to use.