Recent ffmpeg versions fail to use the deinterlacer of nvdec (cuvid). Last known version to work OK is 3.3.8. Newer versions drop frames.
Example command, input.ts is a 1080i50 file:
ffmpeg -hwaccel cuvid -c:v h264_cuvid -deint adaptive -resize 1280x720 -f mpegts -i input.ts -vcodec h264_nvenc -preset slow -c:a copy -r 50 -f mpegts output.ts
With 3.3.8 everything works fine, with 3.4 and above we have dropped frames.
frame= 1986 fps=639 q=33.0 Lsize= 13142kB time=00:02:30.52 bitrate= 715.2kbits/s dup=0 drop=1798 speed=48.4x
And output is unplayable.
With ffmpeg 3.3.8 WITHOUT the -r 50 option in output, we also have drops. But with -r 50 in output, we have working file.
Should I report this to ffmpeg? Or is it a cuvid issue that makes it incompatible with recent ffmpeg versions?