strager's blag

Often, videos which people want to include in their osu! beatmaps contain one or more audio tracks. In osu!, videos are used purely for the video track; subtitle and audio tracks are ignored. These ignored assets add up to around 3 megabytes of wasted space (or more) in many cases; most BAT's and MAT's point out that a video's audio track should be removed before the map is ranked to reduce bandwidth and disk usage.

Sadly, dealing with video files is not trivial for the average osu! mapper. Large, clunky programs like Sony Vegas are suggested for mappers to remove audio tracks and to perform further compression. These programs are confusing to use for simple tasks such as removing the audio track, and most of the time the program tries to re-encode the video track when saving ("exporting") the changes.

A solution I often use for video editing (including recompression) is mencoder. It's free, CLI-based, and has nice static Windows builds available. With mencoder, removing the audio track is simple:

mencoder -nosound -ovc copy -of avi -o output.avi -- input.avi

This also removes subtitle tracks (as AVI doesn't support subtitle tracks) and any other video tracks (because AVI doesn't support those, either).

Of course, end users won't be able to execute mencoder easily without a GUI; if they could, they'd probably be using mencoder or some other program which Just Works™ anyway. I've developed a Windows batch script (.bat) which allows for drag-and-drop of videos to strip the audio. The script, paired with a static Windows build of mencoder, is available for download here.

I've uploaded the script to osu-public on Github. It's under the WTFPL v2 and anyone can fork and make changes as they wish.