What does Gknot send in the job to VirtualDub?

[Swan]

This is perhaps a dumb question, but after studying GordianKnot's log file on a video I just encoded, I became curious just what happens when Gordian starts to encode. I use DivX 3.
I see interesting stuff like "SetMotionDetection(8,10,300,300" and "SetLumaCorrectionAmp(0,10,30)" and "SetQualityControl(2,16,0,20)" in the log.

GordianKnot sends a job to VirtualDub (not Nandub, right?), but with what parameters?
If I wanted to encode a movie, using 2-pass and the same settings, in Nandub, what things would I need to set up, for it to be identical with how GordianKnot does it?

Also, I'd love to know what the ecf contains and why it is important. If I wanted to encode a video in Nandub, how would I create an ecf, if I didn't have access to GordianKnot? I know how to create one in Gordian, under Nandub Files.

/Swan

[manono]

Hi Swan-

DivX3 uses only Nandub. If you wanted to use GKnot settings, but run Nandub yourself (I used to do it that way), then make your 2nd pass Modified Stats File in the Stats File Editor Tab (after loading the Stats file from the first pass in the Nandub Files Tab), do what you want in there, and hit Calculate and then Save, and then create the ECF File in the Nandub Files Tab. Then open the .avs in Nandub, go File-Load Processing Settings-GordianKnot_Default.vcf (it's in the GKnot-Nandub folder-maybe move a copy into your movie folder). Then when in Nandub, Go Video-Fast recompress, and then Video-SBC Options-SBC Settings. In the ECF Tab, load the ECF. In the Bit Rate Curve Tab, Encode Using the Modified Stats File. And then in the DivX Tab, fill in the Bit Rate and the Minimum Allowed Bit Rate (those are in the file name of the Modified Stats File). Then go File-Save As AVI, and the second pass is underway (unless I forgot something-it's been awhile). While in there, you can study the other settings that GKnot uses. Don't forget to fill in the Audio File Size and the Interleaving values so GKnot can calculate the Bit Rate correctly.

If you wanted to run the first pass also by yourself, then make the audio in advance and fill in the size and interleaving values, load the default.1st.pass.vcf (in File-Load Processing Settings-it's also in the GKnot folder-Nandub), and go Video-Fast Recompress, and File-First Pass, and name it Movie.stats or something like that. Piece of cake.

To see what an .ecf contains, open it in Notepad.

[Swan]

manono, thanks!
I will give this a shot tonight.
I want to, just for fun, encode an episode of a Tv-series I have captured and encode to DivX 3 with Nandub, manually. Just using Gordian for the compressibility test and for calculating the correct resolution and bitrate to use.

I love Gordian, but I want to unravel the GordianKnot and see if I can emulate what it does, so I learn more about Nandub and DivX-encoding, manually. :)

One thing I wonder about is, I always want Antishit enabled (with the setting you recommended to me ages ago and which works great). Should I set Nandub to Fast Recompress during the first pass anyway? Shouldn't I use Full Processing then? Or is that just necessary during the Second Pass in Nandub?

Previously, when I've encoded using 2-pass in Nandub, I downloaded "Nandub Options Explained" and looked at Doom9's guide and from that, created a vcf I load.
It's bascially a copy of the recommended settings in Doom9's Nandub guide. I did not mess around with the settings, followed the guide to a T. I may have made a mistake, of course.
I then used Gordian for the cropping, compressibility test, etc and made an .avs script. Loaded this into Nandub, loaded my vcf and encoded.

But Gordian's encodes look better.
I'm trying to figure out what I do wrong when I encode manually.
My "manual" encoded files don't look bad, but they're not as pleasing as Gordian's.
What is the secret you think?
Is it the ecf?
The Minimum Allowed Bit Rate setting? I have not changed that from encode to encode..
Nor have I ever pressed the "calc" button next to Curve compression (symmetric)in Nandub after the first pass, but I have set a reasonable crosspoint (280). Is this vital?
I use Motion based curve modulation (25%, as in the guide) and have deactivated Bitrate reservoir modulation.
In other words, what settings in Nandub's vcf needs to be changed from video to video (apart from the obvous ones: bitrate, name of stats file, etc)?

The ecf seems to contain information on where keyframes and deltaframes are to be encoded. But why is it so important to use?
And how was this ecf file created, before GordianKnot came along?

Hope I'm not too boring, I just want to learn more. :)

/Swan

[manono]

Hi Swan-

You can use Fast Recompress for the first pass, but if you use Anti-Shit, then you will need Full Processing for the second pass (which might be a reason to switch to XviD or DivX5 sometime, as there is no "shit", so you can use Fast Recompress for both passes).

To compare the differences in settings between what the guide uses and what GKnot uses, just before running the second pass with your GKnot generated settings, go File-Save Processing Settings, and give it a name like GKnot Settings.vcf, and then open them both side by side and compare.

You don't actually need an .ecf unless you make certain changes in the Stats File Editor tab (and then you could load the GordianKnot_noECF.vcf file). But I always had my own keyframe settings (in which case you need an .ecf for sure). I also disabled Motion and Luma Correction, and sometimes raised the minimum Key Frame size, and if certain scenes were giving me trouble, I'd give them more bits. That Stats File Editor Tab is actually quite powerful. In none of the other codecs can you adjust the bit rate for certain scenes the way you can with GKnot-DivX3, or set key frames where ever you want-very useful for anime when the episodes are all run together (and, of course, you can also give the end credits whatever percent you wish). It may work in XviD, but I'm not real sure. You can scale the curve linearly in XviD, and that suits my needs well.