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-   -   problem with downscaling fullHD to dvd (https://www.dvinfo.net/forum/what-happens-vegas/488069-problem-downscaling-fullhd-dvd.html)

Stanley Szpala November 26th, 2010 09:16 AM

problem with downscaling fullHD to dvd
 
hi, I read the relevant posts on this forum, but I still can't do it properly: when play on widescreen portable dvd player or on my PC (1920x1080), I get the picture that has small black bars on all sides (top/bottom and left/right). Without changing the the aspect ratio on the display, I want to have no black bars, or in one direction only.

My workflow:
avchd (USA Canon Vixia HF200) -> Movie Studio 10 -> avi (1920x1080) ->VirtualDub (resize={Lanczos3, new size=720x405, aspect ratio=same as source, 'do not letterbox', not interlaced} -> avi,
->DVDarchitect5 -> dvd

any advice on the settings I should use instead?
thanks

Jeff Harper November 26th, 2010 02:46 PM

Shouldn't your aspect ratio be 720x480? 1.212 pixel aspect ratio?

Craig Longman November 26th, 2010 06:23 PM

As Jeff pointed out, 720x480 with a PAR of 1.2121 is the general setting for widescreen DV. I wonder if the players just look for that resolution and only resize it appropriately when they see that?

And, for the record, square pixels widescreen DV would be 396 (480/1.2121).

Hope this helps,

Stanley Szpala November 26th, 2010 10:52 PM

thanks guys, I had a hard time entering the aspect ratio as you suggested in Virtual Dub, and I did something like this:

new size = 854 x 480, aspect ratio = 'compute height from ratio = 854:480', framing options='do not letterbox'


but my real problem was the wrong template in DVD Architect: I used:
MPEG-2 720x480-60i, 4:3 (NTSC)
instead of:
MPEG-2 720x480-60i, 16:9 (NTSC)

Now the frame nicely fills the screen.

The avi from VirtualDub looks almost as good as FullHD !
The dvd looks good, it fills the screen almost exactly, but not exactly (playing in PowerDVD8). It feels like it doesn't display in the native resolution of the monitor. I need to work on this...

Jeff Harper November 27th, 2010 03:22 AM

the problem with converting to avi before going into architect is architect is reconverting to mpeg 2, which I wouldn't like.

Try this just to see how the results work...put the original video into vegas, render to mpeg 2 using the dvd architect (widescreen 720x480 ) and see what happens.

It will then fit properly and will have only been converted once, and the aspect ration will be exactly correct.

Randall Leong November 27th, 2010 09:39 AM

Quote:

Originally Posted by Jeff Harper (Post 1592535)
the problem with converting to avi before going into architect is architect is reconverting to mpeg 2, which I wouldn't like.

Try this just to see how the results work...put the original video into vegas, render to mpeg 2 using the dvd architect (widescreen 720x480 ) and see what happens.

It will then fit properly and will have only been converted once, and the aspect ration will be exactly correct.

Actually, a quality loss is inevitable no matter what, in this case. This is because the MPEG-2 encoder itself does a very poor job of downsizing, especially on interlaced video. In the OP's case, not only does the video have to be converted (format-wise), but also downsized. And Vegas' MPEG-2 encoder does not use anywhere close to the most appropriate downsizing method (Vegas alone does not offer Lanczos3 resizing at all whatsoever - it offers only bilinear downsizing, which results in major artifacts when resizing pixel aspect ratios). And downsizing the vertical resolution to less than 480 pixels will always result in a loss of image quality no matter what simply because once you downsize the video's vertical resolution to only 405 or 360 pixels, you'll never regain those lost pixels of resolution. As a result, AVCHD downconverted to widescreen SD using Vegas alone will look worse than if that same video is shot in LD (Low Definition) mode (320x240p; there is no 240i).

And the problem here is not the downsizing per se, but the fact that standard-definition video almost always uses non-square pixel aspect ratios while most high-definition video uses square pixel aspect ratios.

Stanley Szpala November 27th, 2010 07:42 PM

thanks guys, I realize downscaling from Movie Studio doesn't work great, and I use Lanczos.
So far the best results I get when:
downscale in VirtualDub,
convert to mpeg (8000Mbps) in Movie Studio,
burn in DVD Architect.

The frame fills the screen nicely now. Quality is not bad, although not as good as SD avi.

I haven't figured out how to avoid resampling in DVD Architect.

Adam Stanislav November 27th, 2010 10:41 PM

Quote:

Originally Posted by Stanley Szpala (Post 1592747)
I realize downscaling from Movie Studio doesn't work great, and I use Lanczos.

The way you said it I get the impression you are assuming that if Lanczos does not work for you, no other method would. I know this is a common myth on this form that "Lanczos is the best." The reality of resizing is that no method is the best for all cases. Each method has its advantages and disadvantages. Lanczos tends to get good results when resizing photographed images. It is quite unsuitable for resizing text, for example. It is not the best for drawings, such as traditional 2D cartoons and graphs.

If Lanczos does not work for you, try a different method.

Gerald Webb November 27th, 2010 11:22 PM

Somebody should really do a sticky about resizing Hd to Sd. It comes up about every week, it just shouldn't cause this much grief.
I know there are lots of workflows, but the simple one that never fails, and seems to be used by a lot of people a lot more clever than me, always works.....

1. Edit in Hd, export to square pixels (1440x1080 1.33 aspect pixels become 1920x1080 square pixels) full Hd in a near lossless codec of your choice.
2. Drop it into Virtual dub, apply the Resize filter to SQUARE PIXEL Sd, This seems to be where it goes wrong for a lot of people-
PAL Sd Widescreen is 1048x576 which equals 720 (which is horizontal width) x 1.4568 (which is PAL widescreen pixel aspect ratio).
So,
NTSC Sd widescreen would be 872x480 which equals 720 (which is horizontal width) x 1.2121 (which is NTSC widescreen pixel aspect ratio).

Then export from Virtualdub to Lagarith lossless codec, and then bring it into you DVD authoring program of choice.
All the DVD programs Ive used know exactly what to do with the square pixel files and you shouldn't have to play with aspect ratios at all, just choose PAL or NTSC and they get it right straight away, well this goes for Architect, Adobe Encore, and my personal fave, Nero Vision.

Stanley Szpala November 27th, 2010 11:48 PM

thanks Gerald, looks like the frame size might be off in my workflow: somewhere on the internet I found the wide-screen to be 854x480, while you're saying 872x480. I'll check it out.
And Adam, maybe I didn't make it clear, but I'm happy with Lanczos in VirtualDub. It's the conversion of SD avi to mpeg2 that appeared to be the weak link.

Stanley Szpala November 28th, 2010 01:05 AM

872X480 is not the same aspect ratio as 1920x480.
Do you recommend 'letterbox/crop' or 'do not letterbox or crop'? The % difference is small.

Stanley Szpala November 28th, 2010 01:40 AM

well, although the frame fits the screen nicely, I see a huge difference between the quality of my dvd and sd avi. Maybe it's normal, but I'm disappointed. I set 8MBps encoding in DVD Architect, and I feed it with uncompressed sd avi (872x480) now.
To be precise, my dvd video looks good when shown in its native resolution, but when I make it full screen, it becomes blurred way more than sd avi.

Randall Leong November 28th, 2010 11:53 PM

Quote:

Originally Posted by Adam Stanislav (Post 1592782)
The way you said it I get the impression you are assuming that if Lanczos does not work for you, no other method would. I know this is a common myth on this form that "Lanczos is the best." The reality of resizing is that no method is the best for all cases. Each method has its advantages and disadvantages. Lanczos tends to get good results when resizing photographed images. It is quite unsuitable for resizing text, for example. It is not the best for drawings, such as traditional 2D cartoons and graphs.

If Lanczos does not work for you, try a different method.

And not only that, but there are many methods that deliver poor results on everything. I have shot scenes that when I used a resizing method that does well on text it ended up ruining the rest of the image with severe artifacts, while using a method that does well on the image made the text unreadable. And worse, an in-between method just rendered both image and text unwatchable.

If those images are what you typically work with, then maybe it's best to shoot in the format that exactly matches the capability of the end user media (Blu-ray, DVD-Video). And if one must downconvert (downsize) such tricky scenes, then maybe it would be better converting from digital HD to analog SD then back to digital SD (using the analog composite outs of the HD camcorder connected to the analog composite inputs of the digital SD capture device)?

Jeff Harper November 29th, 2010 08:21 AM

Stanley, your are using an odd size, it cannot look right. 720x480 is not a suggestion, it is the dimensions it needs to be to play properly on a TV.

You avoid recompressing by rendering to a format that DVDA can use, which is mpeg 2. Please read DVDA help for more information, this is explained clearly there, then come back and let us know what is happening.

John Peterson November 29th, 2010 08:35 AM

Quote:

Originally Posted by Gerald Webb (Post 1592793)
Somebody should really do a sticky about resizing Hd to Sd. It comes up about every week, it just shouldn't cause this much grief.
I know there are lots of workflows, but the simple one that never fails, and seems to be used by a lot of people a lot more clever than me, always works.....

1. Edit in Hd, export to square pixels (1440x1080 1.33 aspect pixels become 1920x1080 square pixels) full Hd in a near lossless codec of your choice.
2. Drop it into Virtual dub, apply the Resize filter to SQUARE PIXEL Sd, This seems to be where it goes wrong for a lot of people-
PAL Sd Widescreen is 1048x576 which equals 720 (which is horizontal width) x 1.4568 (which is PAL widescreen pixel aspect ratio).
So,
NTSC Sd widescreen would be 872x480 which equals 720 (which is horizontal width) x 1.2121 (which is NTSC widescreen pixel aspect ratio).

Then export from Virtualdub to Lagarith lossless codec, and then bring it into you DVD authoring program of choice.
All the DVD programs Ive used know exactly what to do with the square pixel files and you shouldn't have to play with aspect ratios at all, just choose PAL or NTSC and they get it right straight away, well this goes for Architect, Adobe Encore, and my personal fave, Nero Vision.

DVD Architect will re-compress that video. So if you don't like the compression algorithm it uses, you are out of luck quality wise.

John


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