Multiple side-to-side video streams in one file without transcoding

Question

I am investigating a possibility to store video streams which are coming from few sources already coded in h264 without video transcoding as the device I would like to use f

Answer 1

Just specify multiple inputs.

ffmpeg -i [input 1] -i [input 2] ... -map 0 -map 1 ... -codec copy -f matroska [output]

As for the "side-to-side" part, it's up to the player to determine the presentation. If you don't control the player and you need a specific layout or presentation, then you must "burn" all these video streams into a new one and encode it as a new single stream.

Answer 2

If your player can handle it just make it perform the side-by-side view. No encoding or muxing required.

mpv video player

Example using mpv:

mpv --lavfi-complex="[vid1][vid2]hstack[vo];[aid1][aid2]amix[ao]" input1.mp4 --external-file=input2.mp4

The above example assumes each input has the same height. Otherwise you will have to add the scale, scale2ref, pad, and/or crop filters. Simple example using the crop filter to remove 20 pixels from the height:

mpv --lavfi-complex="[vid1]crop=iw:ih-20[c];[c][vid2]hstack[vo];[aid1][aid2]amix[ao]" input1.mp4 --external-file=input2.mp4

See the mpv documentation and FFmpeg Filters for more info.