How to extract the audio from a video (MP4 to MP3)

We extracted the sound of a 45-second, 1280 × 720 video of 14.5 MB into every audio format the converter offers. Each conversion took about a second. The MP3 at the default 128 kbps was 0.72 MB, five percent of the video. Only WAV, which stores the sound uncompressed, came anywhere near the video's size.

MP3 plays everywhere and is the safe choice. AAC sounds slightly better at the same size and is what Apple devices prefer; the sound inside most phone videos is already AAC. OGG was the smallest in our test and plays in browsers and many apps, but some car stereos and older players skip it. For editing or transcription software, choose WAV (uncompressed) or FLAC (lossless and smaller than WAV).

For speech, the default 128 kbps is plenty: our 45-second clip came to under a megabyte, so an hour-long lecture lands around 58 MB. For music, choose 192 or 320 kbps. A higher bitrate than the sound in the video already had cannot add quality, only size: the soundtrack of a typical phone video is AAC at around 128 to 256 kbps, so 320 kbps MP3 is the most you will ever need.

A video without an audio track, such as some screen recordings, has nothing to extract: we tried one, and the converter answered "This file has no audio track, so there is nothing to convert to MP3" instead of producing an empty file. Only the sound is kept; the picture is dropped. And only convert recordings you have the right to use.

The video is "Selfie del futuro" by Alberto Mardegan, a 45-second clip with music from the sample content that ships with Ubuntu, saved as an H.264 MP4 with 192 kbps AAC sound. We converted it with this site's video to audio converters, which run the same FFmpeg commands as our servers, and used a silent 10-second clip to check the no-audio message. A longer video gives proportionally larger audio files at the same settings.