[FFmpeg-user] h264_vaapi missing frames
sw at jkqxz.net
Tue Mar 20 11:58:41 EET 2018
On 20/03/18 02:30, Kai Hendry wrote:
> Hi there,
> With my brand new Intel 8th gen laptop (Intel Corporation UHD Graphics
> 620 (rev 07) with 8 core Intel(R) Core(TM) i7-8550U CPU @ 1.80GHz on
> Archlinux, I thought I'd experiment with hardware accelerated capture
> as opposed to my normal 2-step approach of
> 1) recording to mkv
> 2) converting mkv to mp4
> However with -vaapi_device /dev/dri/renderD128 -movflags +faststart
> -vf 'format=nv12|vaapi,hwupload' -c:v h264_vaapi it seems to skip
> Ffprobe seems to say it's 30fps:
> Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p,
> 2560x1440, 722 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 59.94 tbc
> But during playback, it would appear not!
> Is there a good way to test or know I've dropped frames in my screen capture?
> How can I prevent frame dropping?
Show your command line? The pts values in that file are quite uniform, suggesting that you've forced the output to be treated as if it is 30/1001 fps even if it isn't. The status line also says "frame= 529 ... dup=430", which I think means it has captured 100 frames and made 430 duplicates to keep the framerate.
More information about the ffmpeg-user