As always my programs always try to satisfy a wide range of users, as you say if the resource is clean, it is already of high quality, filters can exclude them, although sometimes a magic touch always serves, even with resources high quality of encoding to obtain smaller sizes, with similar but never identical qualities.
I do not recommend mathematical use for a precise bitrate calculation (9 x 320k = 2880), because it does not exist.
The same thing with the use of the centesimal rule: in practice to get the bitrate multiplies X height X width and divided by 100. example: (640x288/100 = 1843 kbit/sec).
Or the basic bitrate formula is :
(Size - (Audio x Length )) / Length = Video bitrate
L = Lenght of the whole movie in seconds
S = Size you like to use in KB (700 MB x 1024° = 716 800 KB)
A = Audio bitrate in KB/s (224 kbit/s = 224 / 8° = 28 KB/s)
V = Video bitrate in KB/s, to get kbit/s multiply with 8°.
°8 bit = 1 byte.
°1024 = 1 kb
Example
90 minutes video, L = 90x60 = 5.400 seconds
700 MB CD but be sure that if fits use a bit lower like 695 MB, S = 695x1024 = 711.680 KB
Audio bitrate, A = 224 kbit/s / 8 = 28 KB/s
(711.680 - (5400x28)) / 5400 = 104 KB/s x 8° = 830 kbit/s.
The only way to obtain a good (size/quality) compromise is to start from a theoretical point of reference, to a practical result, performed out by several different tests.
