Anyone use Virtual Dub for resizing?

craftech schrieb am 06.07.2009 um 00:57 Uhr
Tried this for the first time. Read that Lanczos 3 was good at resizing.

1. Frameserve 1920 x 1080 square pixel footage from mxf files on timeline. Project is HD 1080-60i (1920x1080, 29.970 fps)
2. Debugmode RGB 32 avi signpost file created
3. In Virtual Dub, Open video file. The avi signpost file.
4. Add video filter - resize.
5. Change filter mode to Lanczos 3. Change New Size from 1920 x 1080 to 720 x 405 (won't allow 480).
6. Check Interlaced checkbox.
7. File/Save as Avi.

Avi file always comes out deinterlaced despite checking the box. I want Interlaced.

Anyone know why?

John

Kommentare

musicvid10 schrieb am 06.07.2009 um 01:00 Uhr
I haven't used VDub for many a year.
But I think it's the lanczos filter.
craftech schrieb am 06.07.2009 um 02:49 Uhr
I tried it with Bicubic resize and it did the same thing. It won't resize an interlaced video into an interlaced video - only Progressive (non-interlaced). Loaded it into Procoder and it says it's non-interlaced. Loaded it into Vegas and under properties clicked match media settings and it says it's non-interlaced.

Virtual Dub resize is supposed to be really good at resizing, but is that only for resizing Progressive footage?

John
Laurence schrieb am 06.07.2009 um 02:49 Uhr
There's a little more to it than that. What you have to do is run three filters all together:

1/ Deinterlace with "unfold fields side by side" tab checked. This will give you two half hight side by side images. For example if your original footage was 720 x 480 interlaced NTSC, your image after running this filter would be 1440 x 240 and consist of two squashed looking versions of the frame sitting side by side. If you looked carefully, you would see that each of these images was what was captured 1/60th of a second apart.

2/ Resize with Lancos 3 to a size that is half the height you actually want and twice the width. Thus to get a 1440 x 1080 end result you would want to resize to 2880 x 560. To get 1920 x 1080 you would resize to 3840 x 560.

3/ Put another deinterlace filter in line with the final option "fold side by side fields together" checked. This will take the left and right images which have been resized and fold them back together alternating even and odd lines.

This will give you the resized interlaced look you are after. I experimented with this quite a bit some time ago, and what I found was that it was on par with any of the best resizing programs out there, but only slightly better than just resizing from Vegas.

To get very close this same look in Vegas, only two settings are important: that your rendering quality is set to best, and that you select a deinterlace method. It is important to set the rendering quality to best because that is the setting that selects which resize method Vegas uses. The "choose deinterlace method" tab is important because checking that tab is what makes Vegas separate the even and odd fields and resize them separately before recombining them into a resized interlaced method. If you leave this tab unchecked, Vegas will resize the image as a single image like it is progressive, and the interlace comb looks terrible resized.
craftech schrieb am 06.07.2009 um 02:54 Uhr
Thanks Laurence. I'll try that.

I am not happy with the look after Vegas resizes 1920 x 1080 interlaced to 720 x 480 interlaced even with those settings so I thought I would try Virtual Dub resize. Maybe it's the square pixels in the footage from the EX1. Not sure.

John
craftech schrieb am 06.07.2009 um 03:33 Uhr
Laurence,

I tried this as follows:

I loaded a 1920 x 1080 intermediate avi file into Virtual Dub. File is Upper Field First interlaced.

Add deinterlace filter with "unfold fields side by side". Left the field order at default since you didn't say to change it. Default is (Keep top field, interpolate/disgard bottom field.)

Add resize filter. Desired size is 720 x 480 so I had to disable Aspect Ratio in order to enter 1440 x 240 in the Absolute (Pixels) box. Filter mode Lanczos 3. Did not check "Interlaced". Unchecked was default. Wasn't sure about that. Do not letterbox or crop left checked (default).

Add another deinterlace filter with "fold side by side fields together" checked. Left the field order at default since you didn't say to change it. Default is (Keep top field, interpolate/disgard bottom field.)

The resulting avi file was a 720 x 480 4:3 Lower Field First interlaced file instead of a 720 x 480 16:9 Upper Field First file.

When you get a chance can you tell me where I went wrong with my procedure?
Laurence schrieb am 06.07.2009 um 05:21 Uhr
Just stick a "field swap" filter in there and you should be fine. You could stick it either at the beginning or the end of the filter chain. It shouldn't matter.
apit34356 schrieb am 06.07.2009 um 08:03 Uhr
Carftech, are you sure to what to compress/resize 1920x1080 to 720x480 without bars?
John_Cline schrieb am 06.07.2009 um 11:00 Uhr
"The resulting avi file was a 720 x 480 4:3 Lower Field First interlaced file instead of a 720 x 480 16:9 Upper Field First file."

As far as I know, a DV-format AVI file is the only flavor of AVI which has a flag in its header that identifies whether the video is 16:9 or 4:3. There is no flag in the header that tells Vegas the field order of the file and Vegas has no algortihm to actually test the field order of the file. It may be that you just need to manually tell Vegas what the correct aspect ratio and field order are. When you pull the video back into Vegas, just right-click on the file, go to its properties and set the aspect ratio to 1.2121 Widescreen and set the Field Order to "Upper."

In Virtual Dub, when you "unfold" or "fold" fields, the field order selection shouldn't matter. I'm certain that you are doing it correctly in Virtual Dub but, like I said, you need to manually set aspect ratio and field order of the resulting file in Vegas since that information isn't part of the AVI file.
craftech schrieb am 06.07.2009 um 12:15 Uhr
Just stick a "field swap" filter in there and you should be fine. You could stick it either at the beginning or the end of the filter chain. It shouldn't matter.
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Laurence,

What about the "Interlaced" checkbox. Checked or unchecked? And why is it coming out 4:3?
Desired size is 720 x 480 widescreen from 1920 x 1080 widescreen so I had to disable Aspect Ratio or I wasn't able to enter 1440 x 240 in the Absolute (Pixels) box. Did not check "Interlaced". Unchecked was default. Wasn't sure about that. Do not letterbox or crop left checked (default). Is that right?

And in the deinterlacing filters are you saying that the setting "Keep top field, interpolate/disgard bottom field" has no effect on the outcome?

Thanks again,

John
craftech schrieb am 06.07.2009 um 12:17 Uhr
Carftech, are you sure to what to compress/resize 1920x1080 to 720x480 without bars?
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I do want the bars.

Thanks Apit,

John
craftech schrieb am 06.07.2009 um 12:25 Uhr
"The resulting avi file was a 720 x 480 4:3 Lower Field First interlaced file instead of a 720 x 480 16:9 Upper Field First file."
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As far as I know, a DV-format AVI file is the only flavor of AVI which has a flag in its header that identifies whether the video is 16:9 or 4:3. There is no flag in the header that tells Vegas the field order of the file and Vegas has no algortihm to actually test the field order of the file. It may be that you just need to manually tell Vegas what the correct aspect ratio and field order are.
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Thanks for the input John.

If I insert media and then go to project properties and click on the folder Match Media Settings it opens the browser whereby I can find the folder with the media I imported. When I click on that it seems to always identify the pixels and field order correctly. Works for the MXF files and Avi files. It identified the Virtual Dub resized media as 4:3 Lower field first. I also tried Procoder 3 and loaded it as a source file. Procoder 3 said the same thing. It identified it as 4:3 and Lower Field first when it identified the media. In Vegas when I displayed the file on an external monitor it was 4:3 and not 16:9.

John
John_Cline schrieb am 06.07.2009 um 13:46 Uhr
Let me say this again; Except in the case of DV-format AVI files, All Vegas and Procoder see is a 720x480 file and neither program has any way to tell whether an AVI file is widescreen or not. PERIOD. The Match Media Setting in Vegas DOES NOT actually "look" at the video and determine exactly what it is and neither does Procoder. You must manually set Vegas' project properties to widescreen. You have to manually tell both programs whether it is widescreen or not and you have to manually specify the field order. It is NOT automatic.

Unlike AVI files, MPEG2 and MXF files DO have a flag in the header which specifically tell Vegas and Procoder that the files are in widescreen format and the field order.

If you set the Vegas project properties to "720x480 DV Widescreen" and import the video you resized in Virtual Dub and set its properties to 1.2121 widescreen and upper-field first first, it will be correct and display correctly. If you really want a 4:3 project and have the video display letterboxed, the select "720x480 DV" for the project settings, but you will still have to set the file to widescreen and upper field.

For that matter, Vegas set to "Best" render quality will resize the video every bit as well as Virtual Dub. Lanczos3 is slightly better when you are rescaling UP in size, but you are reducing so there is absolutely nothing to be gained by going through Virtual Dub. In fact, Vegas basically does the same "unfold", "resize" "refold" method as Virtual Dub. However, in order to get it to work correctly, you will need to have the "Deinterlace method" in the Project Properties set to anything OTHER than "None."
Laurence schrieb am 06.07.2009 um 17:32 Uhr
I would agree with John that any difference in the resize between Vegas and VirtualDub's best Lancos 3 uprez algorithm is minimal. When I did a bunch of tests, sometimes I thought I could see a difference, but most of the time I could not. It's not that VirtualDub doesn't do a really good job of resizing footage. It does. It's just that Vegas does such a great job on it's own.
craftech schrieb am 06.07.2009 um 19:38 Uhr
John and Laurence,

Thank you. I am convinced. And John, thanks for that lengthy explanation. Much appreciated. I'll use Vegas to resize and skip VD especially that (as you said) I am downsizing.

Regards,

John
MPM schrieb am 06.07.2009 um 22:36 Uhr
FWIW, if you can do it in V/Dub, you can do it in AviSynth, plus some. Biggest hassle is Vegas not accepting .avs files, unlike P/Pro etc. [hint hint Sony]. Advantage? 1 is you can use AviSynth to manipulate the file before it gets to Vegas' timeline. Edit HD at DVD frame sizes, render your mpg2, change the script in the avs, change project/media properties, render HD.

RE: field order questions in V/Dub... don't know that it matters but some parts had it reversed -- fixed with latest build out today. FWIW, if you don't mind a more film look, cut fps to 24 at D1 & add pulldown. Or go from D1 <60 to <30 with decimation. Not as correct technically as Lawrence, but can work.

Far as resizing etc., V/Dub & AviSynth are much faster than any NLE I've seen, & AviSynth is a bit faster than V/Dub IMHO, but especially when going small for the web the extra sharpness can be a headache -- Lanczos & bicubic aren't always a good thing (see the AviSynth docs & comparisons).
fldave schrieb am 06.07.2009 um 23:49 Uhr
Also add a Sony Sharpen to the HDV file before downsizing in Vegas. But be sure to set it to 0 (zero). It really does makes a very big difference in the final output.
craftech schrieb am 07.07.2009 um 00:43 Uhr
Also add a Sony Sharpen to the HDV file before downsizing in Vegas. But be sure to set it to 0 (zero). It really does makes a very big difference in the final output.

Set it to zero? Isn't that Reset to None?

John
fldave schrieb am 07.07.2009 um 02:49 Uhr
Set your preview display to Best/Full, then toggle the Sharpen filter (set to zero) on and off. You should see a difference, as others have reported on the forum.

So a setting of zero is not the same as the filter not being in the chain.
craftech schrieb am 07.07.2009 um 03:14 Uhr
Set your preview display to Best/Full, then toggle the Sharpen filter (set to zero) on and off. You should see a difference, as others have reported on the forum.

So a setting of zero is not the same as the filter not being in the chain.


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OK, I'll try it.

Thanks,

John