How to extract an audio track from an MP4 video file on Windows

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Having an MP4 video file I'd like to get just the audio track of it. What makes my question different from the others is that I don't want to convert it (like to MP3 or anything) – I'd prefer to keep exactly the same AAC audio stream that is embedded in the MP4 file without recoding.

I use to play such MP4 files with an audio player (foobar2000, which just ignores the video track in it) on my desktop PC but I'd like to strip the video track off to save space and battery of my handheld.

Best Answer

With FFmpeg, which you can download as a static build (no installation needed) for every major OS:

ffmpeg -i input.mp4 -c:a copy -vn -sn output.m4a

vn and sn disable video and subtitle streams, if there are any. -c:a copy tells it to copy the audio bitstream as-is, without re-encoding the file. This will take less than a few seconds.

Related Solutions

Windows – How to add another audio stream to an MP4 file

After a lot of scavenging around, I've found the best answer I believe. You need to use the Mp4Box command line interface to mux your MP4 file:

mp4box -new -add original_video.mp4 -add extra_track.m4a:disable output_file.mp4

This disable option will cause Quicktime to ignore that track and only play the main one. Quicktime doesn't have the ability to pick audio tracks because it's an awful piece of software, so that's the best you can do.

For WMP, you can switch audio tracks, by going to full screen mode, and then right clicking on the video. It's just that it picks the wrong track by default and you have to live with that. It's a bug in WMP.

Extracting audio from MP4 video into MP3

Use ffmpeg:

ffmpeg -i input_file.mp4 -vn -b:a 128k -c:a libmp3lame output_file.mp3

(Don't forget to adjust the audio bitrate, -b:a, otherwise you might get a huge file even for a low quality source.)

Many digital players actually support AAC audio as well, so you can try extracting the original AAC audio stream, without having to reduce quality even more:

ffmpeg -i input_file.mp4 -vn -c:a copy output_file.m4a

For older versions of ffmpeg, you'll need to use -ab & -acodec options instead of -b:a & -c:a.

Best Answer

Related Solutions

Windows – How to add another audio stream to an MP4 file

Extracting audio from MP4 video into MP3

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