Posted by Joshua Zyber on 10/06/06 00:37

<jamestk9888@webtv.net> wrote in message
news:1160090350.555254.286220@b28g2000cwb.googlegroups.com...
> that was the point of my original post witch is why i asked why dont
> all dvd come in anamorpic like most of the anchor bay dvd's that i
> have
> seen. for the rest see my prievious posts and would someone please
> awnser my questions.

James, you're simply not understanding the process. I'll try to spell
this out as simply as I can.

- All NTSC DVDs are encoded at a resolution of 720x480 pixels,
regardless of aspect ratio. 720x480 is the one and only NTSC DVD
resolution.
- DVD pixels are not square.
- A 4:3 image on DVD fills the entire 720x480 pixel grid and uses all of
those pixels.
- An anamorhic 16:9 image on DVD also fills the entire 720x480 pixel
grid, using the exact same number of pixels.

Are you following so far? 4:3 and 16:9 DVDs are in fact the same as one
another.

- Anamorphic 16:9 DVDs are encoded on disc in a process where the
picture is vertically stretched. If you were to display this on a 4:3 TV
without "letterbox" downconversion, the picture looks distorted. To test
this, connect your DVD player to a 4:3 TV but set it for "16:9
Widescreen" mode and play an anamorphic widescreen disc. You'll see what
the native image on the disc looks like.
- When viewed on a 16:9 TV, that distorted image is now stretched
horizonally across the frame. This restores the proper picture geometry.
However, you're still using 720x480 pixels.
- The only difference between a 4:3 picture and an anamorphic 16:9
picture is that that 16:9 picture's pixels are stretched to be "fatter"
than the 4:3 picture's pixels.

Got that? Good.

Now try to picture what happens when you want to view a 4:3 720x480
picture on a 16:9 screen. The TV can't tell the difference between 4:3
or 16:9 content. All it sees is 720x480 pixels coming in. It's all the
same to the TV. Therefore, since your TV is 16:9 in shape, its first
instinct is to stretch all those pixels to the "fatter" 16:9 shape
that's meant for anamorphic DVDs. This leaves your 4:3 picture looking
distorted.

The thing to do now is to tell your TV that you're watching a 4:3
picture. What it does then is squish the 720x480 pixels back to the
"skinnier" 4:3 shape, thus restoring your picture geometry.

What you're advocating is for the DVD studio to author discs so that 4:3
content is "pillarboxed" into the center of a 16:9 frame. This would
indeed maintain proper picture geometry when watched on a 16:9 TV, but
there's a catch. The DVD is still only encoded at 720x480 pixels. In
order to "pillarbox" the picture, the studio would have to scale that
4:3 image so that it only uses 540x480 pixels, with the remaining 180
scan lines filled with black bars. Your original 720x480 picture has
been downconverted to an effective 540x480 resolution.

When you "anamorphically enhance" a 4:3 picture, you *lose* resolution,
not gain any. Anamorphic enhancement only benefits genuine 16:9
widescreen material.

Additionally, because the studio has authored the 4:3 picture as a
widescreen image with black bars hard-coded on the sides, those viewers
watching on a 4:3 TV now get a picture that's shrunken down and has bars
on all 4 sides. The image *will not* fill their screen.

Are you starting to get the picture?

The best thing for a DVD studio to do is encode all material at the
highest 720x480 resolution and let the TV do the aspect ratio control.
This works out the best for everyone.

If it annoys you that you have to manually adjust your aspect ratio,
there are DVD players on the market that can be set to automatically
"pillarbox" 4:3 content when they read the aspect ratio flag on the
disc. You're still losing resolution with this process, however, because
now the player is downconverting the image to 540x480 pixels and adding
the black bars. It's really best for you to let the TV adjust the aspect
ratio, because the TV doesn't downconvert the resolution.

If anything I've said here still doesn't make sense to you, read it
again.

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