How do merge video files with different resolutions together?

[Guernsey]

Does anyone know of any method that I can use to merge my split files with different resolutions together to form one big file? I want to try doing that with Virtualdub2, AVISynth or FFMPEG.

[jagabo]

Some containers allow for changing resolutions on-the-fly. But some players will not handle such video correctly. For example, ffmpeg can mux different resolution files into an mp4 or ts container:

ffmpeg -f concat -i list.txt -c copy mix.mp4

where list.txt is a list of files in the format:

file 'video1.mp4'
file 'video2.mp4'
file 'video3.mp4'

and the three videos can be of different resolutions.

For a video that plays properly in all players you want to reencode the videos to make them all the same resolution. You can do that in AviSynth with resizing, adding borders, and/or cropping.

[Guernsey]

I see. So you use FFMPEG to mux avi to mp4 but I learned that not every codec is supported by the mp4 container. How do you make it so that FFMPEG know that I want to use mp4 and x264?

For a video that plays properly in all players you want to reencode the videos to make them all the same resolution. You can do that in AviSynth with resizing, adding borders, and/or cropping.

I know FFMPEG can do multiple files but how do you do that with AVISynth?

[jagabo]

In AviSynth you open each video, resize, crop, and/or addborders to make them all the same size, then append the segments.

v1 = WhateverSource("file1.ext").Spline36Resize(...).Crop(...).AddBorders(...)
v2 = WhateverSource("file2.ext").Spline36Resize(...).Crop(...).AddBorders(...)
v3 = WhateverSource("file3.ext").Spline36Resize(...).Crop(...).AddBorders(...)
v1++v2++v3

Then encode the result of the script with the codecs you want.