Can't perform compressibility test

[mazzo]

I'm doing my first Gordian Knot Project right now, and it seems to be ok. But it won't run the compressibility test. It says in the log that it uses DivX 4 on the compressibility check, but I don't have Div X 4, only 3.11 and 5.02, so I wonder why it tryes to use a codec I don't have.

It also tries to read a log file I don't seem to have, called say
shrek_5_perc_05_subs_fDelntrlc_NeutralBicubic_544x288.log , but it can't open it.

Why is that?

[jggimi]

You'll see the words "DivX 4" only because they weren't updated when DivX 4 was replaced by DivX 5.

If the log file was not produced by your compression check, then you had a codec failure.

The most common reason for codec failure is caused by installing GordianKnot *after* installing DivX 5. This is because GordianKnot includes DivX 4... and if you install DivX 4 on top of DivX 5, DivX will be broken. While this may not be your problem...it is the most likely reason.

You can check if DivX 5 is installed properly quite easily.[list=1] Start the Virtual Dub application.
Select Video.....Compression
See if DivX 5 (or DivX 5 pro) is one of the codecs listed.[/list=1]

[mazzo]

That's right, I did. But then I reinstalled 5.02, and reinstalled Gordian Knot excluding DivX4. Then it should work, shouldn't it?

[N_F]

It's always a good idea to install 5.02 after Gordian Knot no matter if you installed 4.x or not. So try reinstalling 5.02 again and then try again.

[mazzo]

oki doki

[mazzo]

Well, done that, but it's the same. Maybe it's not a big deal?

[mazzo]

Nothing works now. It just encodes audio. No video. Here is what is written in shrek_GKnot.kog:

18:20:06: Started DivX5-First Pass: D:\shrek\shrek.avs
18:20:07: Finished DivX5-First Pass. Duration: 0 seconds.
18:20:07: Trying to open Log-file.
18:20:07: Error: Could not open D:\shrek\shrek.log
18:20:07: Error: Could not count encoded Frames.
18:20:07: Speed: 0.000 Frames per Second.
18:20:07: WARNING: Number of counted frames differs from settings!
18:20:07: WARNING: Settings: 119449
18:20:07: WARNING: Counted: 0
18:20:07: WARNING: Difference: 119449
18:20:07: Correcting Bitrate...
18:20:07: Original Bitrate = 1087 k(=1000)Bits/s
18:20:07: ERROR: Correction impossible.
18:20:07: Now encoding at 1087 k(=1000)Bits/s

[jggimi]

You are still having codec failure (0 seconds execution time, no log file produced).

There are several possible reasons for codec failure. These are the three most common, most common first, least common last:[list=1]
Improper DivX 5 installation. You have not confirmed the results of the test I outlined earlier. Can Vdub see DivX 5? Invalid resolution. You don't show enough of the Gknot.log to determine if this is the cause. What is your chosen resolution? Adjusting modulo values (defaults are 16 and 32) downward can produce invalid resolution values. DivX produces macroblocks of 8x8 pixels, the color space requires mod2 minimum, and, even if the encoding works, many video cards are limited to mod16 for playback. AviSynth script errors. Gknot has, in the past, produced invalid .avs scripts. You can check this by opening the .avs file in a player or in Virtual Dub, and scroll around. If you get a failure to load, or if the player or vdub crash, then there is a problem with the .avs script (or the installation of AviSynth). Can you view the .avs video in Virtual Dub or in an .avi player?[/list=1]

[mazzo]

The Solution seems to be the 0.26.1 patch. I rip PAL movies, and is adviced to choose "fast deinterlace". I wonder if that's what went wrong with the 0.26 version, since 0.26.1 has a bugfix related to just that?

I didn't know about this patch before just two hours ago. Now I've tried again, and everything, EVEN the compressibility test, seems to work fine.

Thanks.

[jggimi]

Yes, there was a bug with Fast Deinterlace at 0.26. The bug caused a codec failure -- due to an error in the AviSynth script it produced (error #3, above).

I don't think you should be using any De-interlacing with most PAL DVD content; especially not Fast Deinterlace. There are some helpful hints for special PAL content -- such as content that was sourced from NTSC video -- in the tutorial http://www.doom9.org/ivtc-tut.htm -- if your source was transferred from film, you shouldn't need it.

Fast Deinterlace works by cutting your vertical resolution in half, eliminating every other line of video. It uses the VerticalReduceBy2 filter in AviSynth. This will effectively reduce the image quality of your original PAL DVDs from 720x576 to 720x288. If your final vertical resolution (prior to cropping) would be less than 288, you might consider using it.

I recommend following Doom9's guide for Gordian Knot -- and you'll note that he doesn't recommend deinterlacing normal PAL content.

[N_F]

Originally posted by jggimi
I recommend following Doom9's guide for Gordian Knot -- and you'll note that he doesn't recommend deinterlacing normal PAL content.

Though he does recommend fast deinterlace for interlaced PAL sourced (at least he did the last time I read the guide). I only recently started using decomb instead of verticalreduceby2. But I guess I can understand why, it may be a bit too much going directly to decomb (or other deinterlacer) when you're new to videoencoding.

[hakko504]

IMHO using Fast Deinterlace alias VericalReduceBy2 is a Very Bad Thing™! You loose half the resolution as well as creating a lot of ghosting. Instead I would recommend SeparateFields.SelectEven as it will do the same thing, be faster, and doesn't create the ghost effects. Still even this one should not be used unless you intend to get a small final resolution like 512x288 or 448x336. Note that the last resolution has a higher verical resolution than the original, but in theory pixels may be redistributed without problems AS LONG AS THE FINAL NUMBER OF PIXELS ARE REDUCED. (720*288=202752 > 448*336=150528 > 512*288=147456).
If you don't have fullscreen 16:9 or fullscreen 4:3 I'm willing to bet my money that you have FILM material, and if it looks like it is interlaced then the most likely situation is that you have a field shifting problem, and then Telecide is the way to go.

Oh, and jggimi, in my experience almost all material produced for TV in Europe are interlaced and needs deinterlacing.

[mazzo]

Thanks. This forum is great.

[jggimi]

Thanks for the correction, Hakko. They don't call me "master of misinformation" for nothing. :-)

[mazzo]

Hakko - how do you do that? :::

Instead I would recommend SeparateFields.SelectEven as it will do the same thing, be faster, and doesn't create the ghost effects.

[hakko504]

In the pop-up window where you select FastDeinterlace, you have a button at the bottom called Edit. Press that one and you will be presented with the GKnot-generated .avs. If you use 0.26 Then you should first see a call to VerticalReduceBy2. After that there is a crop call. Put SeparateFields.SelectEven on the line after the crop, and make sure that there is no # first on that line as # is a comment mark and AviSynth will ignore anything after a # sign. In 0.26.1 the VerticalReduceBy2 is already placed after the crop, and you can place the SeparateFields.SelectEven in that part of the script.
Basically your script should look like this (with all remarks removed):LoadPlugin("mpeg2dec.dll")
crop(8,0,704,0) #Only crop to get rid of noise at edges!
SeparateFields
SelectEven
BicubicResize(448,336,0,0.5) #or (512,288,0,0.5) for 16:9
#If needed, add some noise reduction here,
#or if you have the time, before the resize

[jggimi]

You'd have to edit the AviSynth (.avs) script that Gordian Knot creates and sends to Virtual Dub. These files are text files filled with commands, but that act like .avi video streams, that do all of the resizing, cropping, and other changes to the video as it's being fed to Virtual Dub for DivX encoding.

To edit an .avs script, you press the "EDIT" button at the bottom of the "Save & Encode" window. Gordian Knot will open a text editor for you, prior to running the encoding.

You cannot edit .avs scripts for compressibility tests from within Gordian Knot, in the way you can edit a standard encoding job. Edited .avs scripts for those tests have to be manually run through Virtual Dub, and the settings you'd have to make in order to do the test and get proper results imported back into Gordian Knot require some advanced skills. If you want to see the steps, look at http://forum.doom9.org/showthread.php?s=&threadid=37945

[EDIT: Hakko and I responded at the same time, he's just faster than I am.]

[mazzo]

Sorry. No can do. The edit button is grayed out.

[mazzo]

BTW: Can I edit the .avs manually, and THEN start the encoding?

[hakko504]

Sure, no problem.

[mazzo]

I've heard of BOB as a deinterlacing method. How's this compared to SELECTEVEN?

[hakko504]

Well, bob is quite OK, if you use some form of smartbob. The built-in function in AviSynth is really only clip.separatefields.Bicubicresize(clip.width,clip.height) and will produce some quite awful effects, lines jumping up and down, shimmering colors, etc. Xesdeeni's SmoothDeinterlacer (http://forum.doom9.org/showthread.php?s=&threadid=35850) has a doublerate=true parameter that will do a much better job. This also exposes bobs biggest disadvantage as well as it's biggest advantage. It actually doubles the framerate! I have encoded a few clips at 352x288x50fps which have become incredibly fluent, but I'm not at all sure that it actually plays back all 50 frames every second. You need a very good CPU to playback 50fps at fullscreen, that's for sure, so I very much recommends B-frames enabled when encoding 50fps, to make it easy for the computer to decide what frames to discard. Also remember that a bobbed video requires roughly double the bitrate, since there is twice as many frames to encode.

[mazzo]

Sounds interesting. I have downloaded it. How do you use it (with b-frames and all)?

[hakko504]

B-frames are available on the DivX5.0x encoding tab of GKnot. It does require the Pro version to be installed though. At the same place you should make sure the 'Correct video Bitrate' is NOT checked, as we intend to double the framerate. Then add the job to the joblist, but don't start encoding. Now edit the .avs by adding two lines: LoadPlugin("<path>\SmoothDeinterlacer.dll") at the top of the file, and SmoothDeinterlacer(doublerate=true) in the sction where the deinterlacing takes place, still placing it before the crop.
And remember to choose a small resolution, like 384x288, 352x288 or 320x240, depending on how long the movie is. You should not aim for more than 1h/CD when using bob.