How is it different.? setting you mbps you instructing a Constant bit rate.
in ffmpeg, There is no native or true CBR mode, but you can “simulate” a constant bit rate setting by tuning the parameters of a one-pass average bitrate encode: with the -b:v , which is what TVAI does/uses (you can export the command from TVAI and see for yourself it uses the “-b:v” flag). you need to understand (ffmpeg limitation), it is not possible to have constant bitrate for all the frames because of the different frame types and encoding priorities. Hence, if the bitrate is constant over a pre-determined time-period, the video is called a CBR-encoded video. if you want you can tweak your export command to have few extra restrictive parameters to come close as you can to the CBR you are looking for that ffmpeg permits by adding " -maxrate" , " -minrate" & " -bufsize", but those are not usually needed. just set the mpbs in tvai which is sufficient in most cases to act as CBR.
Try something like this in TVAI CLI (change the number to whatever CBR value you want):
BTW - CBR is not a desirable recommended encoding method, unless you doing live stream/broadcast.
CRF is the current recommended encoding method by all means.
I couldn’t make CRF work in the command line with the built-in TVAI ffmpeg, so I export it (in TVAI) as FFV1 (or ffvHuff, sometimes UT-Video) lossless, then handbrake it with CRF.
you need to export the command 1st.
After you set all your presets and filters, setting, export format, bitrate, etc. and ready to “Execute” the job. go to the menu and export the command
Then copy it to notepad and then add those parameters after the “-b:v” “xM” …
once you added those into the notepad, copy the entire text in the notepad and open command in TVAI and past it into the CMD window that was opened.