Advanced help, please...

[MrPiercer]

So, now I'm getting a bit "bored" with the easy-to-use tools like GordianKnot etc.. Sure, it's great for calculations but then?

What I'm looking for would probably be best described as "advanced help & hints"...

I'm really curious about what's really going on "behind the scenes" when I encode and re-encode files.. I guess my curiousity comes from a desire in optimising my work as much as possible.

When I surf around I often come across new tools, like Avisynth 2.5 for example, but it's really not too often I see anything about how to use it....

So, I really like to know what's happening when I do stuff, what parts do what really... First then I can go on and do things manually..

Lets take an example I really would like to know everything about, what apps, tools and what order things are happening.

Ok, here goes...

I have a video file, divx3 video muxed with mp3 audio.
I split it up in Nandub to 2 stream, one audio and one video.
I go to GKnot and do the calculations for resizing the video and notes the values.
Then fire up Virtualdub and open the video stream, put in the resize filter and cropping as needed... Then go to the DivX5 codec setup and put in the bitrate value given by GKnot. Save for both passes.

Ok, then I hit F4 and start the resize and recompress process. But here, what's REALLY happening behind that VDub status screen?

I've understood that to use VDub's resize, I must do the color conversion to RGB and back (Full processing) but that seems like an unneccessary step really...

After some surfing I've understood that with newer mpeg2dec3 and AviSynth + filters I should be able to do this almost twice as fast and without the color conversion. But I don't even know where to begin since apparently no "front ends" supports those new pieces of software...

I'll be happy for any help at all on this, also to me by direct e-mail (anders@norrbring.biz)

Thank you!
Anders.

[Wilbert]

When I surf around I often come across new tools, like Avisynth 2.5 for example, but it's really not too often I see anything about how to use it....
Have you read the YV12 FAQ?

[MrPiercer]

Yes, I read it, several times...

But I don't get it anyway.. How can I do f.x. resizing and cropping WITHOUT the "Full Recompress" option in VdubMod? Every filter option is greyed out in all other settings...

Anders.

[Wilbert]

You have to resize and crop in AviSynth itself. If you read the faq at www.avisynth.org you will know how to make scripts (Q1.13). Also read http://www.avisynth.org/index.php?page=FiltersByCategory for the syntax of Crop(...), AddBorders(...) and BecubicResize(...).

I suggest you use FitCD, see http://shh.dvdboard.de/. It will automatically make a script example for you.

btw, what are the resize and cropping values you got in GKnot? Did you ever look in the avs files that GKnot makes?

[bilu]

You can do everything in Avisynth and then use the Fast Recompress option in Vdub.

Check documentation on Avisynth site. (http://www.avisynth.org)

Most of the time I don't use Vdub at all, just Avisynth and AVS2AVI ( a command line encoder - check the development threads in this forum )

I do all filtering, cropping and calculated resize (you can use functions) on Avisynth.

[trbarry]

Most of the time I don't use Vdub at all, just Avisynth and AVS2AVI ( a command line encoder - check the development threads in this forum

bilu -

Do you find that AVS2AVI is any faster? (on a single processor box)

- Tom

[MrPiercer]

Originally posted by Wilbert
btw, what are the resize and cropping values you got in GKnot? Did you ever look in the avs files that GKnot makes?

Oh yeah, I've looked in them alright, but those values (cropping and size) seems to be of no use when I go to VDub (or VDubMod) and use the resize/cropping there, the values don't correspond, often they're about 10-25% off (in any direction, relly...) for some reason.. So I just disregard those settings and use the bitrate, which seems to be pretty decent.

I don't know if GKnot is the right calculator to use really, I open a already "finished" file and do a compress check for about 10% of the file with the new sizes I want, and from there I grab the bitrate.

Anders.

[Wilbert]

Oh yeah, I've looked in them alright, but those values (cropping and size) seems to be of no use when I go to VDub (or VDubMod) and use the resize/cropping there, the values don't correspond, often they're about 10-25% off (in any direction, relly...) for some reason..
Could you give a concrete example? Then we can calculate it manually and compare it with GKnot, VirtualDub nad FitCD.

[MrPiercer]

Sure, Just give me a little while and I'll dig up some figures for you.. :)

What do you want to know? The original file's compressor, bitrate and video size I guess, and what I want in the other end?

[Wilbert]

If it is a DivX/Xvid only the resolution. If it is DVD: PAL/NTSC, anamorphic/letterbox/fullscreen and amount of black bars. And your target of course.

[MrPiercer]

Ok, here goes:

The original file is DivX3, MP3 audio, 512x384, 23.976fps at 914kbit/s. Total size 189MB. Should be cropped 3 pixels from the right and 4 from the bottom.

I want the result to be DivX5, 640x480, 25fps, same audio.

Anders.

[Wilbert]

Don't crop (cause both have the same aspect ratio), but resize directly to 640x480. Script is:

AviSource("c:\divx3.avi")
BicubicResize(640, 480)

That's all. What values did you use in GKnot and VirtualdubMod ?

[MrPiercer]

Well, I have to crop... The aspect error is so low it won't matter anyway.. If it makes any difference on the quality, I'll just chop off from the 640x480 to be an exact fit.

Well, I didn't really *do* this file, I just made an example... But IF I'd do it, I'd go with the menu options in VDubMod, since I haven't had any deeper looks into what's really going on "under the hood" of the apps. So, I'd go in GKnot and do a compression test for the file and resize to 640x480, and the resulting size in MB, from there I'd go to VDub and there open the original .avi file - NOT the .avs from GKnot.

Then I'd go to VDub's menus and add the bicubic resize filter and do the cropping there.

Then a ctrl-c and set up DivX5 and put in the bitrate value I got from GKnot, and make it a 2-pass run.

And after that, just hit the F4 and start the job. I.e. I won't let GKnot do the actual job, just the bitrate calculation based on the compressability test.

I guess there are LOTS of better tools to use, faster and better.. Since the way I do it, every conversion I do this way ends up in full processing mode with all the drawbacks of color conversion and all that....

[bilu]

@trbarry

AVS2AVI is about the same speed as Vdub, perhaps a little bit slower.
But it's cool for tests :cool: :

avs2avi test.avs test.avi -p 0 -2 -q
(2-pass, priority idle ,not sure of the params, i'm @work now)

Priority idle is about 1-1.5 fps slower (7.3 fps decreasing to 6.8 fps)
and then I browse this forum ;) while encoding 5000-6000 frames.

After encoding I make necessary corrections to my script and run the batch file again :cool: , avoiding a lot of Vdub menus.

I have a P3@850, XP Pro and 192MB RAM

Bilu

[MrPiercer]

Hmmm...
Now I've been looking around for the all-over-the-place mentioned avs2avi app, but wherever I find a link and click on it, it's a dead link... Is there an official site for it, or where can I get? Binary or src doesn't matter much as long as it's possible to compile cleanly with VS .NET

Anders.

[Evil Andy]

You do realise that that avs file that GKnot makes does all the cropping and resizing for you? You don't need to do anything in VDub other than tell the compressor what bitrate to use.

Also, VDub's Bicubic resize is not the same as Avisynth's Bicubic resize (the one GKnot uses in the comp test) so the results of the compressibility test won't be so accurate in regard to your VDub resizing.

[Wilbert]

@MrPiercer,

I have to change that. It's this link http://forum.doom9.org/showthread.php?s=&threadid=36768. Start reading backwards.

Well, I have to crop... The aspect error is so low it won't matter anyway.
What do you mean? You don't have to crop. You can always crop after resizing if there are still black borders (also remember that the crop values have to be even), but that's not necessary.

[MrPiercer]

@Wilbert
Originally posted by Wilbert
You can always crop after resizing if there are still black borders (also remember that the crop values have to be even), but that's not necessary.
Geee... I have to be stupid.. :) I didn't even think about cropping afterwards.. Thanx!
And you say cropping values must be even, I guess you mean that the resulting values always have to be even, or am I mistaken?

Anders.

[theReal]

As Evil Andy already said you can easily do the cropping in Gknot. Then you just save the avs script and copy the "crop()" command into your own avisynth script (this is what I do all the time).

All other commands in avisynth are easy to understand and configure, only "crop()" is driving me crazy without a WYSIWYG frontend. Luckily the new Gknot is now able to open all .avi and .avs files and you can quickly get the correct crop() command line from it.

[MrPiercer]

Originally posted by theReal
As EvilAndy already said: you can easily do the cropping in Gknot. Then you just save the avs script and copy the "crop()" command into your own avisynth script (this is what I do).
Tell me about it.. :) The first 2 values are pretty clear, but the others are backwards... Anyways, thanks for the hint.. :)

[Warning: Don't mistake my high post-count for knowledge!
Oh, I won't.. ;) I've noticed that the more stooopid questions I ask, the more posts I count for... :D