10 hours video - How I made the loop

Here's how I made my 10hrs loop video of the 1st photographed black hole in a 3D reconstruction. 4K video format.

For first I downloaded the whole video in which it was inserted, then precisely cut from start of the rotation cycle, to the end, counting the frames between movements of the coordinates arrows on the left (3).

I then exported 3 segments in VP9 codec, respectively with a fade-in, clean and fade out.

so I calculated how much time to get 10 hours having the single video segment duration and build a list up. It is 4697 minus 2, start and end.

for i in {1..4695}; do
    printf "file '%s'\n" short.mkv >> list.txt;
    done

so added start.mkv and end.mkv to the list.

For the audio I searched for long music in CC-BY on FreeMusicArchive and on Kevin MacLeod's website and assembled in Audacity in order to get roughly 10 hrs.

Exported in *.flac and converted in *.opus (Doing in-software resulted in a failure, not sure why):

ffmpeg -i audio.flac -c:a libopus -b:a 96k audio.opus

uploaded e.thing to the GCP server (8.6 MiB video + 435.4 MiB audio), where I installed ffmpeg and initialized a simple vnc server where I started Xorg and proceeded to assemble everything up:

ffmpeg -f concat -i list.txt -i audio.opus -c copy output.mkv

So I fired a Firefox instance up and uploaded the whole (~15 GiB) in 1 minute or 2.

That's all =)
I figured then out that I could have used the YouTube API someway in order to upload without the Xserver running but, well.. maybe next time I'll give it a try ^^

As usual,
if you found this blog/guide interesting/usefull, I am very coffee addicted ^-^

Cheers,
FraYoshi.