Sometimes when trying to create a short via your phone, you may run into a very unhelpful error that simply states you are unable to preview video.
The Cause
YouTube on mobile is currently very picky about the incoming video file, that it can only have a single video and audio track, and no extra data tracks.
This can be caused by programs like DaVinci Resolve, which always add another data track for timestamps.
The Fix
Pretty straightforward, just remove all the other tracks! But it’s easier said than done. Because those same editors you used to create the video might be the cause of the issue.
Via computer: no re-encoding or quality loss
Thankfully this is pretty easy with ffmpeg https://ffmpeg.org/download.html which is a command line too you can run locally on your computer. If you are unfamiliar with how to set up it up, check out this handy guide https://video.stackexchange.com/a/20496.
ffmpeg -i "VIDEO_NAME.EXT" -map 0:v:0 -map 0:a:0 -c:v copy -c:a copy -write_tmcd 0 "Cleaned Video.mp4"
Open a terminal and navigate to the directory with your video in it. Replace “VIDEO_NAME.EXT” with the name of your file, you can also change the output name from “Cleaned Video” to whatever you want.
Via phone: re-encode
If you’re just looking for a fast fix, open your phone’s default video editor and just change a small thing about the video. Trim it a little, add a bit of contrast, anything to make it able to save a copy of it. Most phone editors out of the box will only save a single video and audio track.
That’s all for this quick tip, hope everyone has a great new year!
