[FFmpeg-user] Difference between videos with libx264 and h264_nvenc

Totte Karlsson totte.karlsson at alleninstitute.org
Mon Feb 24 22:12:59 EET 2020

When using the libx264 encoder on 8bit raw input, the resulting video shows up slightly darker than the original. Using this command:

ffmpeg.exe -y -hide_banner -vcodec rawvideo -f rawvideo -r 60 -s 658x492 -i \\.\pipe\DEV_000F315B978C<file://./pipe/DEV_000F315B978C> -pix_fmt gray -c:v libx264 -crf 23 X:\Videos\One_2020T115817.avi

When running the compression using nvidias encoder, h264_nvenc, the darkening of the video does not occur. Using this command:

ffmpeg.exe -y -hide_banner -vcodec rawvideo -f rawvideo -hwaccel nvdec -r 60 -s 658x492 -i \\.\pipe\DEV_000F315B978C -pix_fmt gray -c:v h264_nvenc -crf 23 X:\Videos\One_2020T120806.avi

Is this known behavior? Any reason for the difference in the resulting video?

Totte Karlsson - totte.karlsson at alleninstitute.org<mailto:totte.karlsson at alleninstitute.org>
Senior Software Engineer - MPE

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