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• How to trim multiple videos and position them to specific position using -filter_complex ?

  16 décembre 2023, par Pavlo Holotiuk

  How do I mix several videos and have them not overlap each other ?
I need to use -filter_complex as I cram many more commands there and seems weird how when I trim video its frames remain and overlap with the other video. I also use tpad to paint the video black where it supposed to be cut but it just makes black images to overlap with other videos instead.

  


  How do I trim and position videos with mix and make sure their frames do not overlap in result ?
Here's the version vithout tpad

  


  ./ffmpeg.exe -i input1.mp4 -i input2.mp4 -filter_complex "[0]trim=start=0:end=5[t0];[1]trim=start=5:end=10[t1];[t0][t1]mix=inputs=2" ./output.mp4

  


  It produces such overlapping frames


  


  When adding tpad overlapping changes to mix of frame and black image

  


  ./ffmpeg.exe -i input1.mp4 -i input2.mp4 -filter_complex "[0]trim=start=0:end=5[t0];[1]trim=start=5:end=10,setpts=PTS-5/TB,tpad=start_duration=5:start_mode=add:color=black@0x00[t1];[t0][t1]mix=inputs=2" ./output.mp4

  


  

  


  The alpha in tpad doesn't seem to do anything either.

  


• ffmpeg combine existing filter_complex with upscaleto e.g. 720p

  24 novembre 2019, par Tom Meyer

  Currently I am combining two videos using this filter :

  -filter_complex "[1:v][0:v]scale2ref=main_w:ih[sec][pri]; [sec]setsar=1,drawbox=c=black:t=fill[sec];[pri][sec]hstack[canvas]; [canvas][1:v]overlay=main_w-overlay_w"

  The output is the following : test.png (Green is the first video input, orange the second one) The whole video (red) has a format of 1600x540 (That might change depending on the input sizes.)

  My question is whether there is a way to upscale this video to maybe 1920x1080 or 1280x720 in the same command. By upscaling I mean to change its size and to fittingly insert black bars on the side/top.

• Normalise video aspect ratio with ffmpeg

  4 juillet 2022, par Benjamin Tamasi

  I'm parsing a video stream from an application that receives an h264 stream and writes it to a file. (The frame data is an unencrypted depacketized H.264 elementary stream).

  


  I use ffmpeg to resize it to a fixed resolution. (I overlay it on a black canvas with -f lavfi -i color=c=black:s=1920x1080:r=30) and -filter_complex [1][0]scale2ref=w='if(gt(mdar\,dar),iw,oh*mdar)':h='if(gt(mdar\,dar),ow/mdar,ih)'[2mp4][base];[base][2mp4]overlay=x='(W-w)/2':y='(H-h)/2':eof_action=pass[vout]

  


  My issue is, that since this stream is coming from a phone's camera, whenever the orientation of the phone changes, the stream's aspect ratio changes. It can go from portrait to landscape, and back, in the same stream. When I open the file in vlc, it handles it quite nicely by resizing the window of the player to match the aspect ratio as it changes.

  


  How can I "normalise" the video, so it's always nicely overlayed on my black canvas as the aspect ratio changes ? Currently it's just using the initial aspect ratio, and if that changes mid stream, it will ignore the change, effectively distorting the stream by squishing or stretching it.

  


  Is there some way I can get ffmpeg to do this ?