Problem rendering Sonic Foundry Text to NTSC DV AVI (Vegas 4.0c)

jdmh wrote on 5/25/2003, 4:37 AM

I am using the Sonic Foundry Text Generated Media event to create a title with the colour of R=255, G=172, B=75 and a transparent (or black) background. However when I render to an NTSC DV avi file, The letters have some white in them towards the right edge (looks sort of like a registration problem).

The problem doesn't seem to happen when generating a PAL DV avi (or it is much less noticeable).

I can reproduce by doing the following:

1) Start with a new empty project (PAL or NTSC)
2) Insert->Video Track
3) Insert->Text Media (just use the default "Sample Text")
4) Change font size (on Edit tab) to 36 (not strictly necessary but results are more obviously wrong at this font size).
5) Change colour (on properties tab) to R=255, G=172, B= 72.
6) Close the Video Event FX dialog.
7) File->Render As... and ensure type is "Video for Windows (*.avi)" and the template is "NTSC DV".
8) View the resulting file in Windows Media Play or within Vegas and the problem with the colour of the letters is visible.

I've tried a couple of other colours as well - the problem doesn't occur with pure red (r255,g0,b0), but it does occur with yellow (r255,g255,b0).

Help would be appreciated. I'm trying to create some NTSC versions of my PAL films for some North American friends, but the titles look really poor :-(.

Thanks!

David

Comments

farss wrote on 5/25/2003, 8:05 AM

Just tried it here, put the rendered file back into the same time line to do an A/B comparison and cannot see any difference.
All looks fine, used to be a problem with text prior to 4.0c but you have that!
Are you using text on black background?

jdmh wrote on 5/25/2003, 9:30 AM

It happens with background set to transparent (which ends up being black) or if I specifically set the background to black.

I've also tried it with a still image rather than the generated media and the same problem occurs so it looks like a problem with rendering with the NTSC DV template rather than the generated media.

Not quite sure what I can do about this or why I'd be getting different results to others. Any hints or suggestions would be greatly appreciated!

David

farss wrote on 5/25/2003, 9:33 AM

I assume you are just looking at it in the preview window, what quality have you got that set to and what render quality do you have set when you do the render to NTSC?

jdmh wrote on 5/25/2003, 7:39 PM

When I looked at it in the preview window, I set the quality to Best (Full). I've also looked at it in Windows Media Player and also captured a still and looked at the result in Paint Shop Pro. The problem is apparent in all cases.

The quality setting when I render is set to Best.

In my preferences:

Ignore third party DV codecs is ticked.
Use Microsoft DV codecs is unticked.

If it is relevant, I am running Windows XP Pro with SP1.

Thanks!

David

farss wrote on 5/26/2003, 2:05 AM

As far as I can see you've done everything correctly, I doubt WinXP has anything to do with it (using Win2K hre). I tried exactly the font,size and color you'd specified, rendered it out as NTSC DV and bought that back onto the same timeline on a track underneath so I could easily switch between sources and they both looked OK.

I've just got a small project rendering at the moment, when its finisehd I'll have another go.

I'm interested in this because I had a lot of trouble with text prior to 4.0c but it turns out the issue was with raster fonts which they have disabled in 4.0c

jdmh wrote on 5/26/2003, 4:19 AM

Thanks, I appreciate the help :-)

Out of interest I tried a couple of other things as experiments:

1) I tried enabling the "Use Microsoft DV codec". Same problem, maybe even a bit worse.

2) I tried rendering as MPEG-2 with the DVD-NTSC template. Problem didn't occur. Unfortunately this isn't a viable workaround because I get other artifacts (strange ghosting) when I try to render my film directly to MPEG-2 :-( I guess this is a separate problem :-()

I'm running out of ideas. Do you think it is worth reinstalling VV3 and seeing if that works any better?

David

jdmh wrote on 5/26/2003, 5:29 AM

Further to this, I've done a bit more playing around. The problem does occur when rendering to PAL, but it is not so bad. You can have a look at some snaps that illustrate the problem at:

http://users.bigpond.net.au/DavidHayward/vegas.htm

David

farss wrote on 5/26/2003, 7:32 AM

Your eyesights a lot better than mine!
I downloaded your NTSC file and opened it in photoshop, zoomed in all the way and now I can see white lines at the edge of the characters.

I have to say I haven't looked THAT closely at whats happening on my PC, still in the middle of a render.

The interesting thing is this seems most pronounced at the vertical edges, and at the edges the pixels are an intermediate color. Looks to me like something wierd is going on when the pixels are being mapped, the conversion to NTSC will make this worse as they are remapped to suit the new screen size.

I'd bet if you rendered to avi and then mpeg2 it will get even worse as well, thats what I've seen happen in the past.

Best suggestion I can make is to lodge a formal tech support request with SoFo, I probably should have suggested this some time ago but I thought this issue was fixed, not just made a bit better. Make sure they know to look VERY closely, they may be as blind as me.

I had a project I'd started in Premiere that I'd rendered out and then bought into VV4. I added more text in VV4 but the text created in Premiere looks better than what I added in VV4 and its a generation newer.

By the way it's good to see someone in Australia using VV!

jdmh wrote on 5/26/2003, 6:36 PM

Thanks again farss, your help is much appreciated. I'll submit a formal support request as you suggest.

David

SonyDennis wrote on 5/27/2003, 12:39 PM

Those small artifacts are typical of the 4:1:1 and 4:2:0 (luma to chroma) color space compression that DV uses. See Adam Wilt's fine articles on 4:1:1/4:2:0 in recent issues of DV magazine.
///d@

jdmh wrote on 5/27/2003, 8:40 PM

Thanks for the pointer SonicDennis. In case anyone else is interested, I was able to find useful info at:

1) www.dv.com: An article called "Uncompressed? Lossless?" by Adam Wilt (Jan 2003).

2) http://www.adamwilt.com/Tidbits.html

If you know of any other sources of helpful info then please let me know. I can't claim to have absorbed it all (all I want is decent looking titles, jeez! :-), but if I've understood correctly, then my possible courses of action are:

1) See if I can find a better codec (unlikely to solve the problem but may improve it).

2) Choose a less saturated colour for my titles.

3) Run a soften or blur filter over the text before rendering. Will look worse on the computer screen, but should improve the result coming out of the codec.

4) Render to a non DV format. MPEG2 NTSC is the target and I would render directly to that except for another problem (documented in a separate thread). However if I've understood correctly, the problem is still likely to manifest when the video gets to a TV (though it would look good on a computer monitor).

Further comments welcome (especially if any of the above is incorrect).

David

mikkie wrote on 5/28/2003, 9:51 AM

Since you're already talking about dv.com, might want to look at Adam Wilts later column on color conversion once it's been DV -> paraphrased, once it's gone it's gone. And the article by John Jackman onkeying discusses the edge prob as well.

Assuming you want to go to 4:2:2, I'm unsure whether it would be best to convert to non-DV 4:2:2 beforehand, or if you'd get the same results rendering 4:1 DV to 4:2:2