Question / Help 60FPS footage results in frame skipping on YouTube

[Urz]

I'm recording 1080p60 footage using NVENC. The produced footage plays at 60FPS in a local video player (VLC reports it as 60FPS), but once uploaded to YouTube there is massive frame skipping. The YouTube stats dialog reports the video as being 59FPS.

I've checked with CRU which shows my monitor refresh rate being 60Hz.

Source file: https://urzlab.com/nvenc cqp 19 1080p60 frame skipping.flv

YouTube upload: https://www.youtube.com/watch?v=SchGQUprxGI

Log: https://pastebin.com/VR8LGSCG

 

[Urz]

As it turns out, this seems to not be an NVENC-specific issue. 720p60 x264 footage results in the same frame duplication once uploaded to YouTube. Below are the files from the x264 recording.

Source file: https://urzlab.com/x264 cbr 4500 720p60.flv

YouTube upload: https://www.youtube.com/watch?v=B8sWsONVHp8

Log: https://pastebin.com/NRRCHSXP

Any ideas for fixing this would be greatly appreciated.

 

[Urz]

I've finally found the cause of the frame skipping. Detailing the solution in case others have the same problem or it needs to be reported to the OBS issue tracker.

FLV (and MKV) files produced by OBS do not correctly report the video frame rate. I noticed that ffmpeg was reading the input frame rate as "62.5", which lead me to this post. Using ffmpeg to convert the container format to MP4 causes the frame rate to be correctly reported both locally and on YouTube as "60".

You can see that the video now plays smoothly: https://www.youtube.com/watch?v=218y92a6lCI

I don't know if this is an OBS issue, or an issue with YouTube's encoder interacting with non-MP4 container formats.