[FFmpeg-user] output bitrate equal to expected bitrate

[Moritz Barsnick]

On Thu, Apr 13, 2017 at 17:55:37 +0430, negin tebyani wrote:
> I need the bitrate to be constant and equal to the one specified (-b:v).

Is there a technical reason for this?

Anyway, it seems libx264 has issues achieving your desired bitrate - it
doesn't have enough information.

For more precise bitrate, try two-pass encoding: Add "-pass 1" first
time round, "-pass 2" second time.

Furthermore (let me google that for you:
https://forum.doom9.org/showthread.php?p=1478388#post1478388), you can
add the x264 option

    nal-hrd=cbr

Note that (I believe) libx264 will pad the bitstream to achieve the
desired bitrate, without adding actual information. Yet mediainfo
reports exact bitrate and CBR, if that's your desire. (I tried it, it
works.)

Moritz