Is it possible to add a support of 60 fps videos to Invidious?
Should be completely possible. Since only 1080p streams can be 60fps, I would consider this a duplicate of #34.
Technically 720p can be 60fps too, but it involves the same technology that regular 1080p streams use.
@omarroth this video has 720p60 quality, according to youtube-dl:
https://www.youtube.com/watch?v=lTiBhGCbwps
Yeah, I misspoke. 720p or higher can be 60fps, not 1080p. But like @Discookie said, 60fps is reserved for DASH streams only. Running ffprobe on an hd720 file reveals:
Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, bt709), 1280x720
[SAR 1:1 DAR 16:9], 1095 kb/s, 29.97 fps, 29.97 tbr, 90k tbn, 59.94 tbc (default)