DV->DivX & Deinterlacing problems

[SpikeSpiegel]

Hi!
This is the 1st time I handle DV files (PAL) and I have some problems

The last version of Avisynth (2.5.3) should support DV files with AviSource, but, when I open the avs file with VirtualDub, appears this message:

Avisynth open faliure:
AviSource: couldn't locate a decompressor for forcc dvsd

Where can I find a DV codec?

Well, anyway this is not important because using DirectShowSource the file is opened with no errors
The REAL PROBLEM is deinterlacing:

I tried with Bob(Avisynth internal), Decomb(Avisynth), KernelDeint(Avisynth) Deiterlace(VirtualDub) and with SmartDeiterlace(VirtualDub)
Bob and SmartD(with threshold=0) produce good quality (no noise, high definition), but the speed is really low
With the other filters frames are full of noise or are too smooth

Which is the best filter/configuration (for Avisynth 2.5 or VirtualDub) for DV deinterlacing?
DV files should be Bottom Field First, isn't it?

[StarRide]

The speed is really slow maybe because you are using DirectShowSource.

I remember DirectShowSource is good if it reads the source from start to finish along the time line, but it has a very hard time seeking and moving back along the time line.

Try loading anything with DirectShowSource, load the avs in virtualdub, seek forward and then seek back. U'll know what i mean.

Simple deinterlacers that just blends the fields in each frame wont be affected much by directshowsource's limitations.

IVTC filters, such as decomb, will have a hard time since for each interlaced frame it checks the previous, current and next frame for matches.

Maybe for SmartD and bob it does something similar, ie. seeking backwards and forwards?

It is much better to find that codec and use something other than directshowsource.

[SpikeSpiegel]

Originally posted by StarRide
Try loading anything with DirectShowSource, load the avs in virtualdub, seek forward and then seek back. U'll know what i mean.

I know, I know, but I fear that this time I can't avoid it:

I'm sure that the codec is already on my OS (even if it doesn't appear on the codec list, WinMediaPlayer can play perfectly that file!), maybe there's something wrong with Avisynth...

Anyway I found 2 codecs, but one (libdv from sourceforge) has a strange extention (have u ever seen .rpm files?) and the other (www.mainconcept.com) is commercial

[StarRide]

Unfortunately, i dont have any experience in DV captures and anything related.

[SpikeSpiegel]

Originally posted by StarRide
Unfortunately, i dont have any experience in DV captures and anything related.

Never mind, neither do I!

Now I'm using DivXPro5.1.1 (it's really faster! ) and SmartDeint. (VirtualDub), so the speed is no so bad (if only I could use AviSource... )

[StarRide]

http://forum.digital-digest.com/showthread.php?s=&threadid=27347

might help you.

and this one also

http://forum.doom9.org/showthread.php?s=&threadid=58110

[SpikeSpiegel]

Thanks!
My situation is very similiar to the one of whom posted that thread:

I was absolutely sure that the codec of the DV file was the Microsoft one (as the one who created the file told me) till, reading that thread, I had a little doubt
immediately I opened that file with VirtualDubMod, but this time, after the error message ("can't find a decompressor..."), I gave a look to the "File Information":
FourCC: [dvsd]
DV codec (MainConcept)....MAINCONCEPT?!?!?!

Probably the program used to convert the capture to DV has MC as internal codec...
I've just downloaded the MC demo version and now I can open the file directly with VirtualDub or with AviSource via Avisynth

[StarRide]

glad that worked. Just use it to decode and u wont have the little watermark of demo to worry about

[SpikeSpiegel]

Ok, now DV support is no more a problem

Now I'm using SmartDeinterlacer with these settings:
Frame-only differencing (field-D is too low)
Blend instead of interpolate in motion areas
Motion th=0 (it's really indispensable for max definition)
Scene change th=100

This way there's no loss of info (all fields are displayed) and no noise-artifacts, the fps is not doubled (like Bob; if fps is too high the file is not supported DVD-DivX players)
the only problem is that, extracting one single frame (if there's motion), the picture will appear blurred (because two fields are blended in the same frame):
this can be a problem if you wanna do "photo editing" with frames, but when you see the whole video it has the only effect of making high motion scenes more fluid.

[Pertwee]

Hi SpikeSpiegel

Can you let me now where this SmartDeinterlacer can be found?

I assume you are talking about a VDubMod filter??? Or am I right up the wrong tree?

Regards,

Pertwee.

[SpikeSpiegel]

Yes, it's a VD-VDMod filter (and, most of all, a Donald Graft filter=great quality), you can find it here:

http://neuron2.net/smart.html

Try different parameters (for example: uncheck "blend.." and select "cubic.." for more sharpness), anyway all depends on the video quality of the source:
if it's low you should denoise it and set the threshold to a higher value (if it's too low, even noise will be considered as motion)

[Pertwee]

Thanks for your prompt input.

The filter is excellent and does just what I want.

Kind regards

Pertwee

[Pertwee]

SpikeSpiegel

Just another quick question regarding de-interlacing if you can spare a moment. Am I right in thinking that there is absolutely no benefit in de-interlacing your video if you compress from 720x576 to 384x288 (PAL of course)??? I have heard some people say that the final quality is still better if you de-interlace the full resolution file first before re-sizing down???

Any thoughts

Regards

Pertwee

[SpikeSpiegel]

Ok, I see we need some theory:

In interlaced videos, each frame is made with 2 fields, each field contains 1/2 of horizontal lines: the first (fieldA) contains "odd lines", the second (fieldB) has the even ones of the video after 1/25" (or 1/30" if it's NTSC) (or vice-versa).
If you separate fields (of a PAL video) you will obtain something like this:

720*576 (PAL 25fps)-> 720*288 (50fps)

This way there's no loss of "info", but the picture is distorted: Bob deinterlace method can fix it doubling each line.
Now there's still a great problem: there's no TV that can display 50fps, so if you don't wanna see it on your monitor, you must halve the frame rate, losing fluidity and definition.
But there's still something whorse: 720*576 (25fps)->384*288 (25fps) (sorry, it was too good to be true..)
This way you lose ALL fieldsB and you're halveing the fieldA lines lenght: thrust me, results are REALLY bad.

[SpikeSpiegel]

The solution is to blend or interpolate fields only when and where it's necessary: this is what SmartDeinterlace does.
I did some other tests and the best configuraton seems to be (assuming that the source quality is good):

for MAX fluidity:
Field-only differencing
Blend instead of interpolate in motion areas
Motion threshold=0
Scene change threshold=100

for MAX sharpness:
Frame-only differencing
Use cubic for interpolation
Motion threshold=0
Scene change threshold=100

All other options must be unchecked.

P.s.
...ah, I was forgetting, there's still another method: Motion Compensation
it's perfect, but it's also a little...expensive
here you can find some info: www.teranex.com