AVS Decimate Command....

TornWingedAngel · Post by **TornWingedAngel** » Tue Sep 30, 2003 12:21 pm

Ok, so when I use the Decimate command in my .avs, I get extremely choppy, slow, and problematic clips. If I just use Telecide WITHOUT using Decimate, I don't get any problems. Any idea what is going on? Do I need to use Decimate to de-interlace my footage? Thanks!

Zarxrax · Post by **Zarxrax** » Tue Sep 30, 2003 1:02 pm

If you are trying to play the avs file in realtime your computer just isnt fast enough to handle it most likely. You must compress to a format you computer can playhback in realtime in order to see the result.

trythil · Post by **trythil** » Tue Sep 30, 2003 5:32 pm

It's also possible that your footage isn't actually telecined.

Telecide doesn't actually do the frame removal necessary to go from 29.97fps telecined -> 24fps progressive -- you can think of it as a deinterlacer optimized for telecined material. (Indeed, part of the Telecide core is an adaptive deinterlacer as a last attempt to get progressive frames.) Decimate actually does the framerate change.

I don't know what you're working with, so I can't say this for sure, but there's a chance that your source may not be telecined. Though here's some general guidelines:

- Anamorphic DVDs (e.g. widescreen) are almost always from film sources and thus can be inverse telecined to 24fps progressive.

- Television series range from 29.97fps interlaced (contemporary anime like Love Hina and Excel Saga) to a mix of telecined and interlaced (FLCL is one of these iirc) to just freaking gross (original Evangelion TV release, Ranma 1/2).
Your best choice for those three cases would just be to use an adaptive deinterlacer, since either the source is originally at 29.97fps (in which case decimation to 24fps will look funky) or the source was originally 24fps but you can't recover the original progressive frames (and therefore just shouldn't bother trying, as chances are you'll make a bigger mess of it if you try to fix it).

As far as I understand Telecide operation, it will first try to combine fields from different points in time to see if it can reconstruct a progressive frame. It'll pass along whatever the best match is, determine if it's interlaced (or in the author's terminology, combed) and then smart deinterlace that. Therefore the reason why you're not seeing any motion problems with Telecide but with Decimate may be because Telecide is just acting as a (really slow) deinterlacer, and Decimate doesn't know any better -- in its default mode of operation it just scans every n frames, looks for the two that match the best, and discards one of them.

TornWingedAngel · Post by **TornWingedAngel** » Tue Sep 30, 2003 10:09 pm

Well I'm working with the Trigun DVD's in fact, (And for God's sake, I'm not putting it to Linkin Park) and I'm going to move my footage to a faster computer to check that out.

If anyone has worked with Trigun DVD's PM me or reply please? Give the dude a little more info. Thanks

NicholasDWolfwood · Post by **NicholasDWolfwood** » Wed Oct 01, 2003 5:24 pm

I'm working with R1 Triguns...they suck. I use Decomb with post-processing on the IVTC...

AkabaneKuroudo · Post by **AkabaneKuroudo** » Fri Jul 16, 2004 4:18 pm

Argh, I have this same EXACT problem. Whenever I use the Decimate() command I get very choppy footage wherever I try to play it. The interlaced avs plays just fine in anything and so does the avs file where I just use Telecide() and not Decimate. Anybody have any suggestions

Scintilla · Post by **Scintilla** » Fri Jul 16, 2004 4:29 pm

Holy necropostage, Batman!

AkabaneKuroudo wrote:Whenever I use the Decimate() command I get very choppy footage wherever I try to play it. The interlaced avs plays just fine in anything and so does the avs file where I just use Telecide() and not Decimate. Anybody have any suggestions

Yeah -- don't use Decimate.

AkabaneKuroudo · Post by **AkabaneKuroudo** » Fri Jul 16, 2004 4:49 pm

hehe, sorry about that ridiculous posting. After mindlessly seaching the through all the old posts I kinda forgot myself for a second...heh. Anyway if I don't use decimate then my footage hasn't truly gone through Inverse Telecine right? I'm trying to IVTC before I edit like it says in the guides. If I don't use decimate now, won't all my editing be off since there are extra frames in there? I'm confused...

Scintilla · Post by **Scintilla** » Fri Jul 16, 2004 5:28 pm

AkabaneKuroudo wrote:hehe, sorry about that ridiculous posting. After mindlessly seaching the through all the old posts I kinda forgot myself for a second...heh. Anyway if I don't use decimate then my footage hasn't truly gone through Inverse Telecine right? I'm trying to IVTC before I edit like it says in the guides. If I don't use decimate now, won't all my editing be off since there are extra frames in there? I'm confused...

If you try a normal IVTC process (Telecide plus Decimate) and it comes out choppy, that most likely means that your source was actually originally done at 29.97, and by IVTC'ing it you're not getting rid of extra frames, but throwing away frames that AREN'T duplicates. With sources like that, you'll want to keep the frame rate at 29.97. It's <i>okay</i> not to IVTC.

AkabaneKuroudo · Post by **AkabaneKuroudo** » Fri Jul 16, 2004 5:39 pm

If I telecide without decimating and view it in vdub I can physically see the duplicate frames, so I think decimate is doing the right thing. Maybe my description of "choppy" is a little off. It's more like lag kinda...in premiere the timecode jumps and its all laggy and everything. I don't know if that helps at all but I dont think its taking out frames its not supposed to since I can go in vdub and check that. The footage is off the Cowboy Bebop Vol 1 DVD. I don't know if that helps at all.