[FFmpeg-user] Encoding CBR with libx264

Reindl Harald h.reindl at thelounge.net
Thu Feb 5 19:26:27 CET 2015

Am 05.02.2015 um 19:18 schrieb Sareyka, Julian:
> I am trying to encode video for adaptive streaming and need CBR for that. So I use the -b:v, -minrate, -maxrate, -bufsize settings.
> But in the end I get a lower video bitrate as configured. With this command I end up with 3200 kb/s instead of 3500 kb/s:
> ffmpeg -y -i 14d7077e-0822-4ab4-ba7f-822df1874936.mp4 -vf scale=1280:720  -pix_fmt yuv420p -c:v libx264 -aspect 16:9 -profile:v high -level 3.2 -r 25 -g 50 -keyint_min 50 -sc_threshold 0 -b:v 3500k -minrate 3500k -maxrate 3500k -bufsize 7000k -c:a libfdk_aac -b:a 192k -ar 48k -ac 2 test.mp4
> I get the same result with different source videos. When looking at the x264 options there is no minrate setting at all. Could it be that x264 does not support a minimum bitrate tolerance at all? Is there another way to archive CBR?

google "x264 cbr" leads to

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