Is that a format that can have a variable visual buffer ?

[kizzie33]

If there a format that doesn't need a fixed visual buffer because this seems stupid. Im trying to transcode 300GB's worth of videos to one standard format.
If i have a low vb then the file is a reasonable size but on a fast moving shoot i loose quality. If i have a high vb then i hold the quality but have a stupid file size.

I have tried different formats, i have tried not putting the vb size but it also errors "rc buffer underflow" so its using a fixed vb size.

Thankyou for your help, im sure its something simple im missing but this is become very annoying. I mean i understand the point of a fixed vb size but surely in the age 4GB computers and 320Mb/s HDD's there must be an alternative.