I found how to trim the beginning of a video to an arbitrary amount without reencoding. I think the `-itsoffset` flag in ffmpeg causes ffmpeg to add metadata to

I found how to trim the beginning of a video to an arbitrary amount without reencoding. I think the `-itsoffset` flag in ffmpeg causes ffmpeg to add metadata to shift the video in time, without reencoding or actually trimming the underlying video. ffmpeg -i video.mp4 -itsoffset 0.25 -i audio.ogg -c copy -y av.mkv