[XviD-devel] Min. framesize

[Dirk Knop]

Hello all,

I'm still experimenting with 2pass curve compression and now I'm a 
little stuck. For getting the "ideal" linear curve while downscaling, I 
have to respect the fact that there _is_ a minimum framesize below which 
downsclaing makes no sense, just stacks up overflow and thus ruins some 
frames/scenes.

My formular is wrong: I now assume the min. framesize is MBs / 9.4 +24 
(in bytes).

There's a bigger fixed bytes part (24bytes is just the avi frame 
overhead). That formular works perfect for 680MBs (e.g. 640x272 
resolution), but for 880 MBs (e.g. 640x352) it is flawed by ~3 bytes. So 
for doing a propper scale I need the _exact_ formular - can anybody help 
me here?

The results achieved now are already better than before, my quantizer 
distribution has only 14 frames with quantizers >5 now (which I consider 
being "bad frames", and this happened due to the formular assuming 
115bytes min frame size wile it's 118 bytes in the 880MBs scenario). 
It's worth to mention that I talk about a 141620 frames movie ;)

Any help is appreciated!

Best regards,
Koepi