Posts for: #Ffmpeg

How to Capture your Bonzomatic with FFmpeg

Got to work on this website https://psenough.github.io/shader_summary/ that try to gather all graphical live coding events performed in the past.

Basically, for people that don’t know, it’s live coding performance done, sometime as a competition, sometime as a jam, where folks create real time graphics stuff.

One of the common tool used is Bonzomatic , it’s a simple application that use OpenGL to render a rectangle that fit to the application screen and then you can live edit the Framgment Shader that determine what should be the color of the pixel.

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Twitch and FFmpeg and Youtube-dl: Fetch from live stream to local file

(Using Windows PowerShell, adapt for UNIX bash shouldn’t be a big issue)

Record a live stream

So something nice with youtube-dl is like you can ask not to download the media but to fetch for the media link :

>> youtube-dl -g https://www.youtube.com/watch?v=RJt01u4yrLQ
https://r2---sn-h0jeened.googlevideo.com/videoplayback?expire=1[...]

If you use that for a twitch channel that is streaming live, it returns you the HLS stream.

>> youtube-dl -g https://www.twitch.tv/farore_de_firone
https://video-weaver.ber01.hls.ttvnw.net/v1/playlist/CpkEQusnrcdffNI3[..]MA2c4.m3u8

It by default binds to the best quality video, but you can check and select all format available using -F

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Extract chapters from Youtube Media

Update: Since a while, youtube-dl isn’t as powerful as it is. Fortunatelly another fork exists : yt-dlp . Use this instead

Youtube recently got this “chapter” concept where it fragment a long video with chapters. I think this data might be parsed from the description of the video done, as they already parse any timestamp available for a while now.

Thanks to youtube-dl, we can download thena video and the metadata which now contains this chapter data.

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