Confused about file size

[Polarbear]

Hello All,

Have been playing with Divx for a while and only recently been playing with Xvid. I am still very uncertain about the file size issue. Previously with Divx (GMC, Bi-Direction), I could pretty much ALWAYS hit the 2CD mark, regardless of movie type or length, pretty much (99% Hollywood NTSC movies). With Xvid (VHQ-2, Qpel, Chroma, B-frame), I am getting (greatly undersized, 100-150megs) <2CD sized movies quite often, when I set it to 2-3CD encodings.

I don't have much time to do many encodings as of yet, but two movies that turned out 100-150meg short of 2CD marks are Superman II and A Walk to Remember. Superman II is >2 hours in length and has quite of lot of 'action' (736 x XXX), so I would assume it will definitely hit the 2CD mark, but it's almost 100megs short. Or am I doing something seriously wrong here?

Using latest GK System + Codec pack.

Is Xvid simply better at not 'wasting' space as compared to Divx, meaning that it will try its VERY best to preserve lower file size if it already 'maxed' out the compression?

Thanx in advance,
Cheers,
-Polarbear

[ominte]

In XviD's settings change "Max Overflow Improvement" and "max Overflow Degradation" to 30. This should solve your problems, otherwise post your settings so we can see where you may have gone wrong.

[Teegedeck]

Hm, what do you expect us to say? You've got to find out yourself whether the encode really was saturated, first. Also I'd recommend doing compressibility tests (as you use GKnot anyway) before encoding to prevent any surprises.

Do a search, you'll find lots of posts about 'undersized' and 'saturated' encodes. Perhaps you'll find them helpful.

[Imperial Llama]

Originally posted by Polarbear
Is Xvid simply better at not 'wasting' space as compared to Divx, meaning that it will try its VERY best to preserve lower file size if it already 'maxed' out the compression?

Both XviD and DivX will have a point at which the compression will max out. If you are using more then 1 consecutive b-frame then XviD may max out before DivX. However different movies will reach different maximum files sizes and the variation between movies is likley to be much bigger then the difference between using XviD and DivX.

To find out if your movie has maxed out load up the stats reader reader that should be in the XviD folder in your start menu. If you load your stats file generated from the first pass the stats reader will tell you what the maximum size will be.

Please also look at the advice and suggestions that were given to you in the previous thread you created about this. The fact that you have started a new thread rather then continued the old one leaves me wondering wether you bothered to even read it. :(

[Selur]

If you normally go for 2CD+ Rips, you also might want to try other quant matrices,..

And plz post your b-frame settings and the version of xvid you used.

[Polarbear]

Sorry guys,

I am still very new to Xvid, and I have read some of the posts, even including the 'saturated' or 'undersized' posts, but am still a bit confused, most importantly, still getting GREATLY undersized films very very often. As mentioned, I have personally not yet gotten an undersized film with Divx, so I am a bit confused here basically. And, right, best way to verify is to do 2 encodings or test it out, but I simply do not yet have the CPU time right now.

I tried the statsreader thing, it mentioned:
Frames: 137775
Size (MB): 1176
Max framesize: 134469

kBlk: 7
bBlk: 841
uBlk: 26

What exactly am I supposed to do with this? I assume 1176 MB means that I will be UNDERSIZED again, after setting final file size to 1490. My Xvid settings are as follows:

6-Ultra High
MPEG
XVID
2-Limited Search
300
1
Chroma
Qpel

B-Frame: (2 / 150/ 100 / 0)

Alt. Curve: (Max bitrate: 10000 / Max overflow improvement: 30 / Max overflow degrade: 30)

Please offer some suggestions, and try not to flame me.
Cheers,
-Polarbear

[iago]

Yes, this means undersize again if your ac3 track doesn't fill up the remaining space. If you don't wanna do another first pass (with higher resolution, disabling b-frames, etc.) or especially wanna keep the ac3 track, start your second pass and go for 1CD with ogg or mp3 audio. And try not to exceed a 1stPass/2ndPass ratio of 2/1 when deciding on your audio size.

regards,
iago


edit: or if you have got a first pass output and you are pleased with the quality, just mux the a/v streams and do not care about the undersize! ;)

[Polarbear]

Thanx for prompt reply,

The audio quality is personally not of concern to me, the primary concern is that of the visual quality. I want to try to attain the highest visual quality possible at 736 x XXX (Already a very high res. for NTSC blockbuster movies on DVD, I think.) I read some things that people say, b-frames of 2 do not affect the quality, am I correct? Meaning that it only helps to reduce the file size, but doesn't affect quality?

I can't personally spot the differences in 'quality' encodings now due to my crappy monitor and lack of HDTV, but I hope someday (year 2030+) to get one of those things. Essentially, if infact, my saturated film is visually as good as it gets with xvid, and on-par, if not surpass that of divx, which is bigger in file size, that is the end of my concern.

Thanx again for the help, guys.
Cheers,
-Polarbear

[iago]

In a "constant quant encode" (first pass output -> quant2 for I/P frames, and quant4 for B frames with your b-frame settings), quality will always be higher "without" b-frames.

regards,
iago


(Personally I would go for 1 CD in your situation, or do the first pass again disabling b-frames and/or using a high-bitrate custom matrix, together with LanczosResize - though I don't know if it's already Lanczos that you used ;))

LOL, if only the problem with all encodes would be merely 'undersize'! ;)

[Teegedeck]

Or (this is the part where I always get preachy;) ):

- encode using the full anamorphic resolution (no resizing)
- remove all noise-filters from your script (if there are any)

[/preachy]

[Polarbear]

Quick 'stupid' question...

How do I do Anamorphic under Gknot? (no noise filter used at this time). I am thinking of doing Anamorphic and disable B-frame after seeing all your comments. What do you guys think? Since I cannot as of yet hit the 3CD mark with any of these NTSC films I'm doing.

-Polarbear

[Nibor]

In GKnot there's no built in function or something like that.
You just don't do any resizing, just cropping!
The different part is not to create the anamorphic encodes, but to make it automatically playback in correct aspect ratio.
Hmmmmm... It's not that easy to explain :)

If you're really interested, I suggest you to read this thread (http://forum.doom9.org/showthread.php?s=&threadid=54677&highlight=anamorphic), there's a complete instruction how to do anamorphic encodes.

[Teegedeck]

Alternatively, you could skip cropping, too, and resize in BSPlayer - the aspect-ratio 16:9 is already defined. But the matroska/ffdshow way is so nice, yeah.

Edit: To prevent resizing, open tne avs-script that GKnot created, find the line with the resizer-command in it ('LanczosResize(736...)' or similar) and delete it or put an '#' at the beginning of the line.