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Old 27th January 2009, 01:26   #1  |  Link
weaker
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Confused about interlacing, flags and encoding

Hi all,

this is my first analogue capture, so please bear with me.

I capture VHS tapes via S-Video-In on my ViVo capable Geforce 6600GT. I use VirtualVCR and the nVidia WDM drivers to capture to lossless Lagarith AVI in full PAL resolution (720x576). The card only supports capturing UYVY, that's why I use YUY2 in Lagarith.

I think I'm going to do the processing with AviSynth when I figured out how to use Lagarith with it and avoiding colorspace conversion to RGB through DirectShowSource() (Is that possible at all?).

In the end I want a DVD for watching on TV as a target platform and perhaps a progressive PC-only video in x264.

After reading the guide and the DVD FAQ I am confused and have several questions regarding the DVD:

As I capture interlaced video from VHS, what would be the best steps to preserve as much quality as possible?

1) Don't deinterlace, interlaced workflow, perform denoising/contrast enhancements/etc. only on fields (using SeparateFields()) and weave() at the end
Encoding with HCenc as interlaced MPEG-2 and creating a DVD with interlaced flag set.
Deinterlace last for the progressive PC-only vid.

1b) like 1) but denoising/etc. on the frame as it is (with both fields interlaced)

2) Deinterlace first and then perform denoising etc.
Encode with HCenc as progressive MPEG-2 and flag the DVD as progressive.

3) First perform denoising, luma/contrast correction then deinterlace.
Encode as progressive and flag as progressive.

4) Is there any case where it could make sense to set HCenc to progressive and flag the DVD interlaced (or vice versa)?

I hope I was able to pose the questions clearly. Thanks in advance.


PS: Why is HCenc not mentioned in the capture guide?
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Old 27th January 2009, 02:06   #2  |  Link
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There is no best, per forum rule 12.

There's no canned answer without knowing your source and the filters you want to apply. Knowing the source is necessary to know whether is is film or video, or something pathologic; the processing will be different depending on the result. Knowing the filters is necessary because some can be run on interlaced source and some can't.

You should post a specific source sample and tell us what problems you see that you think can be helped by filtering. Then we can help you generate a good processing chain for it.
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Old 27th January 2009, 18:54   #3  |  Link
weaker
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I know about rule 12 and that's why I explicitly stated that I want to preserve quality (which means that speed is not my concern). I'm sorry if that wasn't clear, English is not my mother tongue. I just want to avoid making mistakes regarding the processing order of the filters.

The source is "home-made" videos from an interlaced video camera/camcorder. I am quite sure that the source is truly interlaced and not progressive separated into fields (which I think was the intention of the film/video question?).

I try to find a suitable source image that shows what I want to process.

Thanks so far

EDIT: Here is a sample picture from the source. I just saved it as PNG otherwise it is unaltered.

Last edited by weaker; 27th January 2009 at 19:29.
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Old 28th January 2009, 04:07   #4  |  Link
linyx
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A short clip (10 seconds) would be far better for determining interlacing types, etc.
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Old 28th January 2009, 04:42   #5  |  Link
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I would keep it interlaced.
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Old 28th January 2009, 11:44   #6  |  Link
2Bdecided
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If you make a progressive DVD, you'll completely change the look of the footage, changing all the smooth movement into stuttery jumpy movement.

You may need to go
interlaced > progressive > process > re-interlace
if the processing (e.g. your choice of denoiser) only works on progressive content.

Cheers,
David.
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Old 29th January 2009, 00:16   #7  |  Link
weaker
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Thanks for your comments! I think I will keep it interlaced then for the DVD.

I have found a thread about aWarpSharp used to reduce chroma bleeding. I tried it after deinterlacing (TDeint+NNEDI) and it works very well. I'd like to use that filter for the final processing.
If I understand 2Bdecided right, I can use this filter (and similar progressive filters) like this:
SeparateFields() --> chroma-bleeding-filter --> Weave()

2Bdecided: It sounds as if I deinterlace for viewing on a PC (progressive) it is necessary to use double rate deinterlacing to keep the movement smooth?
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Old 30th January 2009, 11:41   #8  |  Link
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Quote:
Originally Posted by weaker View Post
2Bdecided: It sounds as if I deinterlace for viewing on a PC (progressive) it is necessary to use double rate deinterlacing to keep the movement smooth?
Yes. Be aware that this isn't as compatible as same frame rate deinterlacing - some older hardware might not be able to keep up. Being "PAL" it'll never look as smooth on a PC as on a TV (unless your PC monitor runs at 50Hz - very unlikely). Still smoother than 25fps though.

Cheers,
David.
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