>On Thu, 16 Jun 2005, Matto Marjanovic wrote:
 ...
 >> One would expect the _quality_ of the encoding to vary though.  With the
 >>  24fps input, mpeg2enc should have more room in the same file to store
 >>  real information.  With the telecined input, mpeg2enc will squander
 >>  some of its limited bit reservoir in encoding those redundant fields.
 >
 >      Is it reasonable to say:
 >
 >      If it's not bitstarved in the first place (i.e. isn't using
 >      all the bits it was given) then reducing the amount of data 
 >      substantially should result in a smaller (even less bitstarved)
 >      file? 

Sounds reasonable to me.
I've kind of imagined that at "-q 2", mpeg2enc is almost always bitstarved,
 in the sense that it is getting close to being asked "please try to 
 encode this losslessly, if possible".

    704 * 480 * 1.5 * 8 * 24 = ~97,321 kbps
                             /   6,400 kbps
                           ------------------------
                            15:1 compression ratio required


    704 * 480 * 1.5 * 8 * 30 = ~121,651 kbps
                             /    6,400 kbps
                           ------------------------
                            19:1 compression ratio required

"-q N" kind of translates into "minimum compression ratio".
 "-q 2" probably equates to less than "15:1".  (Yes?  No?)
 Following that logic, until a 'q' minimum is chosen which falls between
 15:1 and 19:1, you won't see much difference in file size.
 
It'd be neat if mpeg2enc provided some statistics as to the 'q' levels
 it actually uses per frame (since the command-line parameter is just
 the minimum).

-m


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