Thank you!

[JarrettH]

Hi there...

I'm new and have learned so much from using the search function. :p

I have learned that...

- at least HALF of the settings are subjective!
- QPel is generally regarded as a good thing
- Chroma Motion is generally regarded as a good thing
- Trellis, in my opinion, is a good thing but only to be used with the H.263 Quantization Matrix (yeah, yeah...it *can* work with the others but generally isn't suggested)
- Max I-Frame interval should be YourFrameRate X 10
- VHQ is subjective (although I have searched here and apparently, by testing, VHQ1 offers the best quality...probably by miniscual amounts nobody can perceive so everyone leaves it at 4 because it takes longer)
- B VOP is subjective, after reading a lot about this, I have decided not to change anything
- Turbo only affects B VOP and QPel
- GMC's benefits aren't worth it at this time
- and countless other tidbits from the unofficial XviD guide

I did a lot of experimenting with Alien 3 Special Edition. I tried putting it on 2CDs (it is 2hr 25min). The highest bitrate I could manage was 905kbps plus using the AC3 audio track.

I used 2-pass, QPel, Chroma, default B VOP settings, unticked Turbo, VHQ1, and I/P/B quant=3. I did this using H.263, HVS-Best, and SixOfNine=24. H.263 was less detailed, HVS-Best was more detailed, and SixOfNine was just as detailed as HVS-Best, but I thought the noise in the picture was less apparent then it was with HVS-Best so I stuck with this version. Alien 3 has A LOT of smoke and 'atmosphere' in the picture if you know what I mean. The cinematography in it is gorgeous and innovative in a few ways (rotating steady cam in the corridors). It's my favourite of the series. I'm quite pleased with the results!:)

After all this research, I have decided most of the XviD defaults are best.:D heh

[Teegedeck]

Welcome to the forum! I hope you enjoy your stay as much as your encoding.

Just one thing:

Originally posted by JarrettH
- Trellis, in my opinion, is a good thing but only to be used with the H.263 Quantization Matrix (yeah, yeah...it *can* work with the others but generally isn't suggested)
? Why - where - what?!? :confused:

[Audionut]

Originally posted by JarrettH
After all this research, I have decided most of the XviD defaults are best.:D heh

I would agree. Except to enable trellis by default, as AFAIK, the problems associated with trellis have been fixed.
Custom Quant Matrix. Namely SixOfNine24.
Max I-Frame interval should be YourFrameRate X 10

Oh and totally not related to xvid, but, Removegrain (http://forum.doom9.org/showthread.php?s=&threadid=79751)
Removegrain with unfilter is a good way to shave approx 20% off the bitrate needed, with out quality loss.

[JarrettH]

Thanks Audionut, I'll redo the SixOfNine and maybe HVS using Trellis.
Is it possible to use those filters with VirtualDub? (they didn't load properly) I have AviSynth, but I'm not into scripting at all.

[Blue_MiSfit]

Definatley learn how to do basic scripting... all you have to do for a basic script is something like this


#plugins
loadplugin("c:\yourplugins\mpeg2dec3.dll")
loadplugin("c:\yourplugins\unfilter.dll")
loadplugin("c:\yourplugins\undot.dll")

#source
mpeg2source("c:\yourVobs\movie.d2v")

#crop and resize
crop(whatever,whatever,whatever,whatever)
lanczosresizze(whatever,whatever)

#denoising filters
unfilter(-5,-5)
undot()


thats all it really takes
1) load plugins
2) select source
3) perform functions

complex scripts are beyond me too, but anyone can write a script like this...

Learning how to at least use avisynth filters without something like GK is essential to maximizing quality from your rips, even for someone with little to no experience. That ulfilter(-5,-5) call will have almost no perceptible effect on the movie, but will boost compressibiltiy by 10-20%. I ALWAYS use it now.

[JarrettH]

Is there a way to estimate how much a filter such as those can compress? Say if I wanted to use a filter and predict how much it could compress so I could increase the bitrate while still fitting it on 2 discs.

[Blue_MiSfit]

there's no way to tell without doing a compressibility test.

add something like this:
SelectRangeEvery(280,14)
to the end of your avs.

this will feed 14 frames every 280 frames (thus 5% of the movie) to whatever application you use for encoding (virtualdub or whatever).

Encode at whatever settings you want to use, but make sure to use single pass constant quantizer 2. This will generate a file that represents "best quality at current codec settings". You can then open the resultant file in vdub, go to file - file information.

check the average delta frame size and multiply that by the number of frames in the movie to get a rough idea of how big a movie will be at full quality using whatever settings / script you cook up.

do this several times with various combinations of filters / xvid settings to determine what you want the final encode to be. usually you can make your final filesize about 70-80% of your predicted size and still get good quality. Just play around and see what happens, that's the best way to learn xvid / avisynth

[Chainmax]

For compressibility gains I use RemoveGrain(mode=2) and/or Deen("a2d",1,3,5). Neither of them seem to cause significant detail loss, but then again my eyes aren't as well trained.
BTW, JarrettH, when you start learning how to do basic scripting, remember that less is more, meaning that you should use the least possible amount of filters. You will pretty much always get better results by fine-tuning a couple of filters than by throwing lots of them in your script.

P.S: Enc (http://jonny.leffe.dnsalias.com/enc/index.htm) appears to be a pretty nifty compressibility test tool.

[JarrettH]

Thanks for all your help everyone.
Every day I'm seeing how big a role AviSynth plays in encoding, even some apps won't work without an AVS script.:eek: