[FFmpeg-user] SLOWNESS WITH LIBX265 CODEC

[Hervé ANSELME]

Hello all,

I have a question about libx265 codec I use to re-encode video ; by the way I use the 6.1 release of ffmpeg, running on Windows 11 Family OS.

The output file ( re-encoded film ) created in MP4 format has a quite good audio/video quality ; but the process took quite a long time to execute : for a source film which length (or movie duration) is 1 h 32 min, the re-encoding process took 1 h 12 min.

Here is the command line I used to create the output film :

ffmpeg.exe -loglevel error -sn -i "D:\temp\input_film.mkv" -map 0:v:0 -map 0:a:0 -acodec libmp3lame -ar 48k -b:a 128k -q:a 3 -vcodec libx265 -vf scale=720:520 -sws_flags lanczos+accurate_rnd -b:v 1200k -minrate 1200k -maxrate 1200k -r 25 -qscale:v 2 -x265-params "nal-hrd=cbr:force-cfr=1:vbv-maxrate=1200:vbv-bufsize=1800 "  -log_level -1 "C:\temp\output_film.mp4" -bufsize 1843200

In my command line, do anybody see parameter(s) which should be fixed, in order to reduce process duration, if possible with keeping the quality of the output file ?

Or maybe there are excess parameter(s) in my command line, in order to reduce process duration ? If so, which parameter(s) ?

Or maybe there are missing parameter(s) in my command line, in order to reduce process duration ? If so, which parameter(s), and how this (these) parameter(s) should be configured ?

Thanks for your help.

Regards,
HA