Problem: join a bunch of videos together.

Many people took videos of themselves saying happy birthday for my mother in law. I had the task to joining them together with ffmpeg.

This was harder than it looked because:

  1. Some Videos (shot on iphone) used an HDR colour space. I ended up reshooting these in SDR.

  2. Some videos were different sizes, so I used ffmpeg to add letterboxes for the right sizes.

  3. Actually joining the videos results in quite a long ffmpeg command line.

I ended up writing a program to generate results, with the command line below.

ffmpeg -i 1.MOV -i 2.mp4 -i 3.mp4 -i 4.mp4 -i 5.mp4 -i 6.mp4 -i 7.mp4 -i 8.mp4 -i 9.mp4 -i 10.MOV -i 11.mp4 -i 12.mp4 -i 13.mp4 -i 14.mp4 -i 15.mp4 -i 16.mp4 -i 17.mp4 -i 18.mp4 -i 19.mp4 -i 20.mp4 -i 100.mp4 -filter_complex '[0:v:0]colormatrix=bt709:smpte170m,scale=480x640:force_original_aspect_ratio=decrease:in_range=full,pad=480:640:-1:-1:color=black[c0]; [1:v:0]colormatrix=bt709:smpte170m,scale=480x640:force_original_aspect_ratio=decrease:in_range=full,pad=480:640:-1:-1:color=black[c1]; [2:v:0]colormatrix=bt709:smpte170m,scale=480x640:force_original_aspect_ratio=decrease:in_range=full,pad=480:640:-1:-1:color=black[c2]; [3:v:0]colormatrix=bt709:smpte170m,scale=480x640:force_original_aspect_ratio=decrease:in_range=full,pad=480:640:-1:-1:color=black[c3]; [4:v:0]colormatrix=bt709:smpte170m,scale=480x640:force_original_aspect_ratio=decrease:in_range=full,pad=480:640:-1:-1:color=black[c4]; [5:v:0]colormatrix=bt709:smpte170m,scale=480x640:force_original_aspect_ratio=decrease:in_range=full,pad=480:640:-1:-1:color=black[c5]; [6:v:0]colormatrix=bt709:smpte170m,scale=480x640:force_original_aspect_ratio=decrease:in_range=full,pad=480:640:-1:-1:color=black[c6]; [7:v:0]colormatrix=bt709:smpte170m,scale=480x640:force_original_aspect_ratio=decrease:in_range=full,pad=480:640:-1:-1:color=black[c7]; [8:v:0]colormatrix=bt709:smpte170m,scale=480x640:force_original_aspect_ratio=decrease:in_range=full,pad=480:640:-1:-1:color=black[c8]; [9:v:0]colormatrix=bt709:smpte170m,scale=480x640:force_original_aspect_ratio=decrease:in_range=full,pad=480:640:-1:-1:color=black[c9]; [10:v:0]colormatrix=bt709:smpte170m,scale=480x640:force_original_aspect_ratio=decrease:in_range=full,pad=480:640:-1:-1:color=black[c10]; [11:v:0]colormatrix=bt709:smpte170m,scale=480x640:force_original_aspect_ratio=decrease:in_range=full,pad=480:640:-1:-1:color=black[c11]; [12:v:0]colormatrix=bt709:smpte170m,scale=480x640:force_original_aspect_ratio=decrease:in_range=full,pad=480:640:-1:-1:color=black[c12]; [13:v:0]colormatrix=bt709:smpte170m,scale=480x640:force_original_aspect_ratio=decrease:in_range=full,pad=480:640:-1:-1:color=black[c13]; [14:v:0]colormatrix=bt709:smpte170m,scale=480x640:force_original_aspect_ratio=decrease:in_range=full,pad=480:640:-1:-1:color=black[c14]; [15:v:0]colormatrix=bt709:smpte170m,scale=480x640:force_original_aspect_ratio=decrease:in_range=full,pad=480:640:-1:-1:color=black[c15]; [16:v:0]colormatrix=bt709:smpte170m,scale=480x640:force_original_aspect_ratio=decrease:in_range=full,pad=480:640:-1:-1:color=black[c16]; [17:v:0]colormatrix=bt709:smpte170m,scale=480x640:force_original_aspect_ratio=decrease:in_range=full,pad=480:640:-1:-1:color=black[c17]; [18:v:0]colormatrix=bt709:smpte170m,scale=480x640:force_original_aspect_ratio=decrease:in_range=full,pad=480:640:-1:-1:color=black[c18]; [19:v:0]colormatrix=bt709:smpte170m,scale=480x640:force_original_aspect_ratio=decrease:in_range=full,pad=480:640:-1:-1:color=black[c19]; [20:v:0]colormatrix=bt709:smpte170m,scale=480x640:force_original_aspect_ratio=decrease:in_range=full,pad=480:640:-1:-1:color=black[c20]; [c0] [0:a:0] [c1] [1:a:0] [c2] [2:a:0] [c3] [3:a:0] [c4] [4:a:0] [c5] [5:a:0] [c6] [6:a:0] [c7] [7:a:0] [c8] [8:a:0] [c9] [9:a:0] [c10] [10:a:0] [c11] [11:a:0] [c12] [12:a:0] [c13] [13:a:0] [c14] [14:a:0] [c15] [15:a:0] [c16] [16:a:0] [c17] [17:a:0] [c18] [18:a:0] [c19] [19:a:0] [c20] [20:a:0] concat=n=21:v=1:a=1[outv][outa]' -map '[outv]' -map '[outa]' -vsync 2 -pix_fmt yuv420p -c:v libx264 -y ../output2.mp4