Poor compression/low comptest value

[Gen]

Hi,

I'm using Gordian Knot to convert a film (Fando y Lis) to 1400MB avi using the XviD codec. It's a black and white film, NTSC 29.970fps interlaced and the AR's 1.66, but I'm having a problem with the compressibility test. It's usually pretty easy to get 70-80%+ as comptest value with a decent resolution, but this time I've found that the comptest value is very low, and I'm not sure if there's anything I can do about it.

I've searched around for some info and found The Scientist's and manono's posts in this topic were pretty handy: http://forum.doom9.org/showthread.php?t=121381

From what I understand, I'm limited to either reducing the resolution or increasing the file size. But at a resolution of 608x384, increasing the file size to 2100MB still only puts the comptest value at 57.9%. In order to get a 70%+ comptest value at 1400MB, I'd have to reduce the resolution to 432x272, which is much too small. The audio's 192kbps AC3, 133MB in size, so it doesn't really take up that much of the 1400MB space. I tried converting the film anyway just to see what it would look like at these settings, but it was very blocky.

So...is there anything else I could do to increase the quality, or am I basically out of options? Any help would be appreciated!

[manono]

Hi-

So, did you make it 23.976fps by using Force Film in DGIndex? Surely you didn't leave it interlaced.

Filtering can help to make a film more compressible, but with the tradeoff of a softer picture.

Also, based on the pics here:

http://www.dvdbeaver.com/film2/DVDReviews30/Films_of_Alejandro*_Jodorowsky.htm

it looks a bit green and should be greyscaled.

[Gen]

Ah well that's the thing, almost all my DVDs are PAL region 2, so I wasn't sure what to choose this time because I'm used to selecting "Honour pulldown flags". When I previewed the film, it said the framerate was 29.970 and it was interlaced, so I searched for an answer. I found an example of someone selecting "Honour pulldown flags" for their NTSC interlaced film, so I went with that instead of "Forced film".

Anyway, I didn't leave it interlaced, I used tdeint(slow=2) which worked fine, but the resulting avi was blocky because of the compression problem.

As for the greenish image, kudos for spotting it, but my copy is actually the original Fantoma release. I'm not sure why Anchor Bay decided to fiddle with it when they re-released it, I just took a snapshot of my copy and I think it looks fine in comparison: orig. (http://img.photobucket.com/albums/v390/genxide/vlcsnap-4277903.png) vs. AB re-release (http://www.dvdbeaver.com/film2/DVDReviews30/a%20robert%20siodmak/a%20fandysPDVD_008.jpg)

[manono]

OK, I was assuming you had the same one as the review. If it's interlaced, then most likely it needs to be IVTC'd. Make the D2V project file using Honor Pulldown Flags (as you did, I think), open it in VDub(Mod) without further filtering (no deinterlacing), scroll to a spot with movement and start advancing a frame at a time. If, in every 5 frame sequence, you see 3 progressive frames and 2 interlaced frames, then it's been hard telecined - had the telecine encoded into the video. The answer to making it progressive again is an IVTC and not a deinterlace. The IVTC will bring the framerate down to 23.976fps and give you a big boost in compressibility. Deinterlacing a movie is about the last thing you want to do.

If it's not as I think it is (the 3/2 pattern), then maybe post a small 10 second sample somewhere so we can have a look. Use DGIndex and its [ and ] buttons to isolate a small section. Then File->Save Project and Demux Video. Upload the resulting M2V to someplace like MediaFire.

[Gen]

Thanks for all your help!

I went through a sequence of frames, but most were interlaced, the 3/2 pattern didn't seem to be there. Regardless, I tried IVTCing and converting it anyway, but the result was a dud. Anyway, I've uploaded a small clip as you suggested (~13MB - http://www.mediafire.com/download.php?wdkdyr92mpo )

[manono]

Darn. I should have known when you mentioned Fantoma that it was going to be crap. I've run into their garbage DVDs before. How badly do you want to do this one right? Ready to learn some AviSynth?

First go and get the R-Pack:

http://forum.doom9.org/showthread.php?t=95924&highlight=MRestore

You'll also need an up-to-date version of TIVTC and MaskTools, both linked in that same first post. You'll also need a bobber. Get Yadif or LeakKernelDeint, or TDeint. I'll use KeakLernelDeint for the job. Get it here:

http://avisynth.org/warpenterprises/

Read the MRestore.txt file that's included. Stick the MRestore.avs in your AviSynth Plugins folder or someplace else, if you like. You have to Import the MRestore.avs into your script. The script might go something like this:

LoadPlugin("C:\Path\To\DGDecode.dll")
LoadPlugin("C:\Path\To\LeakKernelDeint.dll")
LoadPlugin("C:\Path\To\MT_MaskTools-26.dll")
LoadPlugin("C:\Path\To\TIVTC.dll")
Import("C:\Path\To\MRestore_v23e.avs")
MPEG2Source("C:\Path\To\FandoyLis.d2v")
LeakKernelBob(Order=1)
MRestore(Numr=2400,Denm=6000)

Notes about the script: I couldn't make the latest MRestore unblend it properly. I don't know why. In the "Old" folder inside of the R_Pack is version 23e which I'm using. Your sample uses top field first (Order=1 in LeakKernelBob). The DVD is probably the same, but to be sure run the Preview in DGIndex and check the field order. You can use any bobber and I usually use Yadif myself. The KernelDeint included in GKnot doesn't have a bobber included, but the modified LeakKernelBob does. If you get an error message when testing it in VDub(Mod) and can't figure it out, post it here along with your script. If it opens, go File->File Information to make sure the framerate is 23.976fps.

It's 23.976fps, but it hasn't been telecined. It's been field blended. You can put on LeakKernelBob by itself (without the MRestore line) and see all the blends/ghosts/double images. MRestore is an unblender. A standard IVTC won't work. Deinterlacing just keeps all the blends. This won't completely unblend it, but will do a pretty good job and it should play smoothly, and it should increase the compressibility because of the lower framerate. I realize you'll have other filters, including crops and resizes. Add them in as well. Let me know if you have any problems. This will improve it greatly, but it'll never look as good as it would if Fantoma had done it correctly.

[Gen]

Ah, you're a legend! As you pointed out, the DVD quality isn't great anyway, but it's just finished encoding and it worked pretty darn well - a lot better than my first attempt. When I compared the DVDs online, the picture quality swayed me, but I've learned my lesson; I'll be sure to avoid Fantoma's releases in future.
I'm still very much a novice with this type of stuff, but I already had MRestore and the other plugins you suggested, although I'd only used them once. In fact, I've had them ever since I came across field blending with another film not too long ago, and I saw one of your posts in the Video Help forums advising someone. Anyway, :thanks: