[cnelson87]

hello,
Long time reader, first time poster...
I know all about making mpeg VCD's - I've read all the tutorials and downloaded all the tools. But one thing I'm a little unclear on is video resolution. Everything I've read says 352 x 240. But if NTSC is 720 x 480, shouldn't it scale down to 360 x 240?
Regardless, 352 x 240 for my source footage isn't working for me. After exporting to mpeg in QT or Toast I have black bars at the top and bottom. Either that or the sides are cropped off. And the end result is 320 x 240. If my source footage is 320 x 240 everything is OK. Sort of. There's about a 1 or 2 pixel difference between crop and fit.
Can anyone offer an in-depth explanation of what video resolution to use and why?
Thanks,
C.

[Theodour]

I don't know how in-depth I can go, but ...
The VCD format uses a slightly better resolution than VHS. VHS is, being analog, doen't have a digital comparison, but it uses something like 200 horizontal scan lines.
VCD is thus a bit better at 352x240. VCD does not use square pixes, obviously. The picture is squished a bit horizontally. That is just how VCD works. Note: Quicktime player will report VCD files as 320x240. I don't know why.
The picture is sampled up and squeezed to become the 640x480 tv screen we know and love.

DV (iMovie and FCP's format), along with DVD are based on non-square pixels too: 720x480. Their image is squeezed horizontally, but that is it. No upsampling. That is why DVD looks better than VCD in general (However, with carefully encoding, and quality source footage, you can pull off some remarkable quality VCDs)

In general, the term "pixel aspect ratio" is used in describing this non-square pixel phonomenon.
When making your VCD mpegs, start with regular footage -- 720x240, and let the encoding software downsample to 352x240.

[cnelson87]

Thanks Theodour, what you say makes perfect sense, and basically follows everything I've read. But, unfortunately, doesn't quite work exactly as stated.
I've ripped a couple minutes from a DVD (one that I own, for the record) at four different resolutions: 720x480, 640x480, 352x240, and 320x240. 720 and 352 just don't work! Using both Toast and QT Pro, I either get black bars at the top and bottom if I use the "fit" option, or the sides are cropped off if I use the "crop" option. 640 and 320 work perfectly; no black bars and no cropping.
So, I've come to a conclusion. VCDs aren't really 352x240. Well, they sort of are; they're upsampled from 320x240, then squashed back down to a 4:3 display ratio. What a convoluted process! I really don't understand why the encoding software has to upsample to 352x240 then back down to the original 320x240, but that's what it does.
Anywayz, these are my results. I would be very interested in hearing someone else's real-world results if they differ from mine. In the meantime, I'm just gonna save on hard-drive space and rip away at 320x240.
C.

[Theodour]

cnelson,
You might be able to find your answer here, though It is pretty technical looking:
<a href="http://mpeg.telecomitalialab.com/" target="_blank">http://mpeg.telecomitalialab.com/</a>
Also, try some of the links at mpeg.org.
Here is what I have tried, and it works ok for me--but this is captured video, not ripped from DVD. The stuff you get off a DVD might be 16:9 stuff, and I don't even think that can be made into VCD ... hmmmm ... unless you either sqiush it, or allow for gaps on the top and bottem ... in fact, that might be what is going on with your stuff.
But for real, no fooling, VCD really is 352x240. Why? I don't know ... as Dr. Suess says, go ask your dad.

</font><blockquote><font size="1" face="Geneva, Verdana, Arial, sans-serif">quote:</font><hr /><font size="1" face="Geneva, Verdana, Arial, sans-serif">Originally posted by cnelson87:
<strong>Thanks Theodour, what you say makes perfect sense, and basically follows everything I've read. But, unfortunately, doesn't quite work exactly as stated.
I've ripped a couple minutes from a DVD (one that I own, for the record) at four different resolutions: 720x480, 640x480, 352x240, and 320x240. 720 and 352 just don't work! Using both Toast and QT Pro, I either get black bars at the top and bottom if I use the "fit" option, or the sides are cropped off if I use the "crop" option. 640 and 320 work perfectly; no black bars and no cropping.
So, I've come to a conclusion. VCDs aren't really 352x240. Well, they sort of are; they're upsampled from 320x240, then squashed back down to a 4:3 display ratio. What a convoluted process! I really don't understand why the encoding software has to upsample to 352x240 then back down to the original 320x240, but that's what it does.
Anywayz, these are my results. I would be very interested in hearing someone else's real-world results if they differ from mine. In the meantime, I'm just gonna save on hard-drive space and rip away at 320x240.
C.</strong></font><hr /></blockquote><font size="1" face="Geneva, Verdana, Arial, sans-serif">