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Old 4 May 2003, 01:42 AM   #1
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Default DVD2AVI, Forced Film, Decomb Telecide()

I'm getting a little confused as to what I should be using as my settings in DVD2AVI and what actual difference they make.

All the movies I'm ripping are 29fps, Film Type: NTSC. I've tried using both Filed Operation:None and Field Operation: forced film and it just doesn't seem to make any difference.

I'm also kinda unsure as to what seetings I need to use with Decomb in conjunction with my DVD2AVI settings

LoadPlugin("C:\Program Files\AviSynth 2.5\plugins\MPEG2Dec3.dll")
LoadPlugin("C:\Program Files\AviSynth 2.5\plugins\decomb.dll")
mpeg2source("C:\newproject\myproject.d2v")
telecide()
decimate(cycle=5)
Crop(8,4,704,472)
LANCZOSResize(512, 384)

or

LoadPlugin("C:\Program Files\AviSynth 2.5\plugins\MPEG2Dec3.dll")
LoadPlugin("C:\Program Files\AviSynth 2.5\plugins\decomb.dll")
mpeg2source("C:\newproject\myproject.d2v")
FieldDeinterlace()
Crop(8,4,704,472)
LANCZOSResize(512, 384)

? is there a difference. I can't seem to see one, but I wanna make sure I'm doing things right. Can anyone tell me what I should set field operation to in DVD2AVI and what code I should use to deinterlace my movie in my avs file?

as always, many thanks

thomas
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Old 4 May 2003, 01:57 AM   #2
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this article explains ntsc, pal, ivtc, forced film etc.. also when to use forced film and when to use ivtc and when to use deinterlace etc.

http://www.doom9.org/ivtc-tut.htm

I found it very helpful
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Old 4 May 2003, 04:54 AM   #3
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Ok, I've read the guide.

I've examined my movie after creating an avs like this

LoadPlugin("C:\Program Files\AviSynth 2.5\plugins\MPEG2Dec3.dll")
LoadPlugin("C:\Program Files\AviSynth 2.5\plugins\decomb.dll")
mpeg2source("C:\ITVC\notforced.d2v")
Telecide(post=false)

my dvd2avi project file was saved with field operation=None.

When looking through my movie frame by frame in VirtualDub I can see that every frame has interlacing lines. So after readin the guide I'm told that pure interlaced DVD's cannot be ITVC'd and must be de-interlaced.

So can someone just confirm I've got this right, with my pure interlaced DVD I need to save my DVD2AVI project film with "Field Operation=None".

Then my AVS script should be like this:

LoadPlugin("C:\Program Files\AviSynth 2.5\plugins\MPEG2Dec3.dll")
LoadPlugin("C:\Program Files\AviSynth 2.5\plugins\decomb.dll")
mpeg2source("C:\ITVC\notforced.d2v")
FieldDeinterlace()

Is that right? so I'm deinterlacing while still at 29fps?

I'm still really unsure if I need to include anything in my script relating to Telecide or decimate.

Telecide(post=false) ? or should I not write anything for this?

many thanks

thomas
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Old 4 May 2003, 08:45 AM   #4
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Unless you know that your particular source is an originally-FILM NTSC material (which is very often the case), stick to a normal deinterlacer. Inverse Telecine will not work indeed with purely interlaced material.

My experience with DVD2AVI's 'FORCE FILM' field operation has been varied. At times, it will work. However, a lot of other times, it does not and that is where the Decomb Avisynth filter comes handy. The best (and easiest) way to find out whether DVD2AVI's 'FORCE FILM' field operation works or not is to simply save the project, open it via Avisynth & Virtualdub, and scroll through the video to see whether you can see any remnants of interlacing artifacts. When you see interlaced frames, you should be able to see similar artifacts anywhere else along the video (the artifacts will not be isolated to one specific set of frames; it can be found throughout the video).

In the above case, you would be better off to fire Decomb instead. Use the default values, which are:
Telecide()
Decimate(cycle=5)

Similarly as above, open the AVS file in Virtualdub and scroll through the video. Should you still see any remaining interlace artifacts, then you know that you have a purely interlaced material (which is uncommon). In that case, you will have to stick to a deinterlacer and dump the Decimate filter as well (reducing the framerate in this case will only result in choppy video).

Cheers!

p.s.
Quote:
Is that right? so I'm deinterlacing while still at 29fps?
Where the Decimate command does not come into play, the framerate will remain unaltered, in this case, 29.97fps.
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Old 4 May 2003, 08:57 AM   #5
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Thanks for the reply.

I'm actually encoding an "adult" DVD, which according to the guide above, most often means is totally pure interlaced.

I've tried various methods now, and all produce the final DivX file virtually identical:

Not Forced Film
Decomb FieldDeinterlace()

Not Forced Film
Telecide()
Decimate(cycle=5)

Forced Film
Decomb FieldDeinterlace()

Forced Film
Telecide()
Decimate(cycle=5)

All the above produce pretty much the exact same file, I can't spot any difference at all between them. Except ofcourse the framerate.

I've checked my movie before any processing in VirtualDub, and I do see interlacing artefacts on virtually everyframe. So according to most guides I read, and the fact that it's an adult DVD and 29fps I'm concluding that this means it's pure interlaced. Which according to the guide linked above means I cannot run any ivtc on it...

However, as all my results turn out virtually indentical, without any stuttering or audiosync problems I'm left totally confused?

thomas
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Old 4 May 2003, 09:12 AM   #6
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What does DVD2AVI say, while you are saving the project or previewing the VOB files, in the Statistics Window under the Video Type section? [not that I depend on this information, but it's good to have a clue of some sort]

On other things,
Quote:
Decomb FieldDeinterlace()
Is this command a valid one? I have personally never seen it at work before.

Quote:
the fact that it's an adult DVD and 29fps I'm concluding that this means it's pure interlaced.
Not quite right.

As far as I know, purely interlaced materials are usually computer-generated videos. An adult material does not differ from any others in terms of the technology used to capture them into video.

What puzzles me though is that the Decomb command does not work for you. Did you open the AVS file in Virtualdub and check, by scrolling through the video IN Virtualdub, for interlace artifacts?
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Old 4 May 2003, 09:28 AM   #7
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Sorry, I was writing that command short hand, my script would have been:

LoadPlugin("C:\Program Files\AviSynth 2.5\plugins\MPEG2Dec3.dll")
LoadPlugin("C:\Program Files\AviSynth 2.5\plugins\decomb.dll")
mpeg2source("C:\DR20\dr20.d2v")
FieldDeinterlace(threshold=25)
LANCZOSResize(512, 384)

When previewing in DVD2AVI, type="NTSC" no percentage is listed. I'm using version 1.6.

I read this on the guide linked above:

Quote:
PURE INTERLACED DVDS. What kinds of DVDs have been produced as NTSC Pure Interlace? Most Sports DVDs, most Concert DVDs, almost all Adult Films, some DVDs made from television series, and movies made on low budgets and shot with video cameras are pure interlaced material. In addition, many of the "Making Of" documentaries and other extras included on DVDs are also pure interlaced material. These can only be deinterlaced. But before you do, be sure to check the frames just to make sure. Don’t just rely on DVD2AVI to tell you. Deinterlace only as a last resort, because of the quality hit you'll take.
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Old 4 May 2003, 09:32 AM   #8
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Quote:
Originally posted by Enchanter
What puzzles me though is that the Decomb command does not work for you. Did you open the AVS file in Virtualdub and check, by scrolling through the video IN Virtualdub, for interlace artifacts?
All the four(shorthand) methods I list above work, this is what I can't understand. They all work the same. They all remove interlacing artefacts and my end DivX movie works perfectly.

If I open my VOB files in DVD2AVI, and save the project without forced film. I then use a basic avs script w/no plugings or filters to open in VirtualDub.

Looking through my movie in Virtual Dub frame by frame I can see that virtually everyframe in a scene with lots of moments contained interlacing artefacts(horizontal lines)...

thomas
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Old 4 May 2003, 09:52 AM   #9
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Quote:
Originally posted by thomaslurv
All the four(shorthand) methods I list above work, this is what I can't understand. They all work the same. They all remove interlacing artefacts and my end DivX movie works perfectly.

.
.
.

Looking through my movie in Virtual Dub frame by frame I can see that virtually everyframe in a scene with lots of moments contained interlacing artefacts(horizontal lines)...
This should not be the case with Decomb.

However, as long as your movies turn out well and working, use whichever that you think looks the best. IMHO, Decomb should provide all the deinterlacing features you need.
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Old 10 May 2003, 03:12 PM   #10
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Quote:
Originally posted by thomaslurv
All the four(shorthand) methods I list above work, this is what I can't understand. They all work the same. They all remove interlacing artefacts and my end DivX movie works perfectly.
I can explain this for you.

First, when you have interlaced video, setting forced film only has the effect of setting the frame rate to 24fps (technically, there are no RFF/TFF flags set so there is no 3:2 pulldown to be suppressed by force film). So eliminating that factor leaves you wondering why Telecide/Decimate and FieldDeinterlace both worked. The answer is simple. FieldDeinterlace worked because the video is interlaced! Telecide/Decimate worked because Telecide does "postprocessing", which just means it deinterlaces frames that come out of the field matching process still combed. Technically, it is not correct to attempt field matching on an interlaced video, but in most cases the original frame gets passed through. However, if you erroneously decimate, your video may become jerky.

Summary: FieldDeinterlace() is the correct thing to do in your case.

Last edited by neuron2; 10 May 2003 at 03:16 PM
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