Minimum Quantizer: 1 or 2?

[plazz2000]

Hi,

A month or so ago I noticed that the default minimum quantizer was changed from 2 to 1.

According to doom9's new XviD 1.0 guide:
Setting the minimum quantizer to 1 won't do any good, just blow up the size of the video.

So what's the recommended setting?

[mikeX]

A minimum quantizer of 1 is the default now in order to avoid undersized files, meaning that a quantizer of 1 will be used only when the desired size (in a 2 pass encode) is bigger than the size achieved at the 1st pass (min quant is 2 there). A quant of 1 usually just bloats filesize with no/little quality gain...
Think of it as a way of avoiding 'Why is my file undersized...' sort of questions
For more information use the 'search' and/or take a look at The Unofficial XviD FAQ (http://www.vslcatena.nl/~ronald/docs/xvidfaq.html), the issue has been discussed before!

[HarryM]

I know. Personally I don't prefer min_quant=1 (xvid default now). I use min_quant=2 always. It is better for me.

IMHO xvid uses quant=1 in another cases too - not only at(potentially) undersized files.

Size of q1-frame is multiply(!) bigger than q2-frame. It causes heavy bitrate curve distortion, e.g.

quant of frames (min_quant=1) -
2323142232323223152323

quant of frames (min_guant=2) -
2323222323232323222223

q1 consumes much much bitrate - codec must compensate this by using relatively high quant at next frame, presently.

[_rEuTeL_]

yep, quality is really fluctuating when setting it to 1
it's very annoying and looks amateurish

I recommend setting the number of B-frames to 0 if your video size is too low

[Jawor]

I also use quantizers 2-31, but there are movies that look bad even at a constant quantizer of 2 (e.g. Roman Polanski's The Ninth Gate). I would have to use constant quant = 1 and B-frames 2/1.00/0.00 to get really good quality, so I've decided not to encode the whole movie, but I used it to test my quantization matrix (see here (http://forum.doom9.org/showthread.php?s=&threadid=74463)).

[Didée]

Hah! Recently I stumbled over Aliens (part 2, if you wish so).

This is the most noisy DVD source I personally have seen so far. With some "normal heavy" filtering, I managed to get an encoding of ~2.0 GB at quant 3 and 704*416. And that result looked very, very poor.

So, this seems to be one of the better test cases for noisy sources.

BTW, being upset by this result, I fiddled a special denoising strategy for very noisy clips. Now it looks quite OK at ~1.4 GB / quant 3. Did only constant quant tests up to now, though.
I'll post the script when I got it generalized so as to be usable as an AviSynth function.

- Didée

[Soulhunter]

Originally posted by Didée
BTW, being upset by this result, I fiddled a special denoising strategy for very noisy clips. Now it looks quite OK at ~1.4 GB / quant 3. Did only constant quant tests up to now, though.
I'll post the script when I got it generalized so as to be usable as an AviSynth function.Cant await to test this with the 25th hour !!!

If you have seen thus flick already, you will understand... :D


Bye