Assume I want to rotate an *.avi or *.mp4 video by 90deg. Therefore I enter something like

ffmpeg -i ...... -vf transpose=1 ....

Which video and which audio bitrate are taken for this necessary re-encoding?
The same as the original?

That would be perfect!

Otherwise: How can I tell ffmpeg: Take the (almost) same bitrates as the original video!

Do I really have to manually fiddle out (e.g. by MediaInfo tool) what the current, old bitrates are?
Is there no automatic detection?

Peter