Bitrate

Hello everybody,
I have a list of videos with different bitrates and I would like to convert this list to a specific format like "mp4". I would like to have this list of videos converted to "mp4" with the same bitrate as the source video, is this possible?

I don't want to use the "Copy" option in the Codec, I want to convert to "MPEG4" for example using the same bitrate parameter as the source, automatically.