Overflow Treatment for low bitrates is botched

[Malevolent]

No matter what i do,
below some limit (dependant on video source)
the codec just insists on making undersized or oversized results.

Example:
First pass (full Q) = 100mb.
Scnd Pass (70% of 1st.) = 70.00mb
Scnd Pass (60% of 1st.) = 60.00mb
Scnd Pass (50% of 1st.) = 49.00mb
Scnd Pass (40% of 1st.) = 42.00mb
Scnd Pass (30% of 1st.) = 33.70mb

The ONLY remedy so far has been seting the overflow values to 0,20,20
and that can't be too good.

This behaviour is invoked mainly when the avg quant goes beyond 4.

-Settings:
All default/all changed/some changed.
-Version: XviD-1.0.1-05062004

[jon.schaffer]

Originally posted by Malevolent
...and that can't be too good.

Hi, just like to know what do you mean by CAN'T. Do you mean that tweaking the values is a bad thing? (1)
Or that the results have a poorer quality than without this tweaking? (2)


If (2), try lower values (e.g: 0, 4, 9). I had this problem, and 0, 20, 20 led to artifacts (blinking blocks due - I think - to a too strong increase and then decrease of the bitrate from a frame to another)

If (1), IIRC, the developers are working on a smarter Bitrate Control...


Yours,
Jon