[XviD-devel] minor changes / todo list

Hans K. Rosbach hk at circlestorm.org
Sun Jun 22 17:16:56 CEST 2003


> on a simular matter, i experimented with some "3rd pass" encoding
sessions,
> where the third pass uses "quant-length" data collected from the 1st and
> 2nd pass to increase desired frame size accuracy.
> in my tests it works quite well (frame overflow decrease by upto 50%),
> however there doesnt seem to be much noticble visible improvement.
> more testing is neccessary.

Just a thought here..

Overflow and Underflow occurs due to a faulty estimation of what the
framesize will be at a specific quant, right?

If so, would it not be a good option to allow re-encode a specific number
of times? Example

//Encode frame with the estimated quant
frame = encodeframe( estimatedquant );

//Check size, if too big then re-encode with a higher quant
if (checksize(frame) > (estimatedsize + allowedoverflow)){
    frame = encodeframe( estimatedquant + 1 );
}

//Check size, if too small then re-encode with a lower quant
if (checksize(frame) < (estimatedsize - allowedunderflow)){
    frame = encodeframe( estimatedquant -1 );
}

Of course, this is just code to illustrate my point. More "AI" is needed,
and
allowing for further attempts as to archive the wanted size.
This would in effect be faster and more easy to use than a 3'rd pass, due to
not
needing to do a lot of other stuff all over again. Of course this does not
allow for
further advantages that might be archived by using another pass, but it
would
allow much higher precicion.

I hope someone likes it, I sure would use this option if available.

-=Dead2=-




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