On Fri, Mar 05, 2021 at 11:33:10AM -0800, Steven Kan wrote: > > >>> > >>> I’d like to assemble these videos, side-by-side, but synced in time, which > >>> means the TrailDown video needs to start 50 seconds after the TrailUp > >>> video. The TrailDown side can be black/blank, or it can be stuck on the > >>> first frame of its video while the right side plays for the first 50 > >>> seconds; it doesn’t matter to me. > >>> > >>> I’ve tried all of the following: > >>> > >>> -itsoffset 50 -i TrailDown.mp4 -i TrailUp.mp4 > >>> -itsoffset 50 -i TrailDown.mp4 -itsoffset 0 -i TrailUp.mp4 > >>> -i TrailDown.mp4 -itsoffset -50 -i TrailUp.mp4 > >>> > >> > >> see tpad filter, need recent version. > > > > Thanks! I have figured out the syntax to pad a single video with tpad, e.g.: > > > > ffmpeg -i > > /Users/steven/Downloads/Record/DownLoad/TrailDown_ch1_20210304010952_20210304011838.mp4 > > -filter_complex "tpad=start_duration=50" tPadOut.mp4 > > > > but I’m having trouble with the syntax to delay only one of two videos in > > an hstack filter: > > > > ffmpeg -i > > /Users/steven/Downloads/Record/DownLoad/TrailDown_ch1_20210304010952_20210304011838.mp4 > > -i > > /Users/steven/Downloads/Record/DownLoad/TrailUp_ch1_20210304010838_20210304011506.mp4 > > -filter_complex "tpad=start_duration=50[v0];hstack=inputs=2” Coyote2Up.mp4 > > > I brute-forced it by using tpad to pad the first video by itself, and then I > used hstack to glue them together. Not the most efficient way of doing > things, and I think that induces 2 generations of transcoding, so ideally I’d > like to know how to do it properly in the future. But here’s the end result:
You need to map your input files to the appropriate filter pads in a complex graph. Since I use this kind of filter graph very rarely, I cannot tell you offhand how to do this properly. The manual section on this should be a good start though. Of course, you can always try the approach I suggested in the other subthread. No transcoding of the original there until you get to the last stage. Peter _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
