How to set the number of B frames in FFmpeg for H.265 encoding?

Question

I would like to re-encode an MPEG4 video into H.265 and want to manually control the number of B frames in the encoding. I tried the following command:

ffmpeg -i test.avi -c:v libx265 -preset medium -x265-params crf=23 bframes=0 test_HEVC.mp4

as suggested by the x265 documentation. However, I got the following error:

[NULL @ 0x7f4e46f82e80] Unable to find a suitable output format for 'bframes=0' bframes=0: Invalid argument

The command works fine without bframes=0, so I must be making a syntax error there. What would be the correct version?

Solution

You must use : as a separator for -x265-params :

ffmpeg -i test.avi -c:v libx265 -preset medium -x265-params crf=23:bframes=0 test_HEVC.mp4

Comments

[Elisa Cha Cha]

If you prefer you can just use -crf option instead of using it via -x265-params. See ffmpeg -h encoder=libx265 for other private options.