Tmpgenc aspect ratios

[bfavre4]

(situation is DV to DVD mpeg2 in Tmpgenc)
Is it better to use 1:1 vga in the source video aspect ratio and also 1:1 vga in the aspect ratio of output? I fear that choosing 4:3 in the output aspect ratio might squish DV's 720x480 to 640x480 (since you set 4:3), then stretch it back to 720x480 since the output frame size is 720x480, all because maybe Tmpgenc doesn't know rectangular pixels. Is this true?

If one uses 1:1 vga for input aspect ratio and 1:1 vga for output, doesn't that mean Tmpgenc will simply read the DV source then encode it, without touching any aspect ratios?

Or does 1:1 vga mean something else? Will it preserve the rectangular pixels of DV so that the mpeg2 file has rect pixels also? (since DVD accepts 720x480 rect pixels)

Also, those source video arrange methods: full screen and full screen keep ratio, and center, center keep ratio, anyone know the differences? The mouse-over text doesn't help much.

Lastly, "enable padding not to be lower than min bitrate" will basically limit the minimum bitrate to the set minimum bitrate, but what does padding mean? Does it compromise quality at all?

[Wilbert]

FitCD suggests to resize it to 688x416, see "http://mitglied.lycos.de/fitcd/".

Why this resize? This has to do with the fact that the pixels on your TV are not square (but 10/11:1), contrary to your PC which has square pixels.

Your DVD with resolution 720x480 will be squized a bit when viewing it on your TV to a resolution of 654.5x480 (note that 720*10/11 = 654.5). This implies that there must be black borders above and below obtaining a picture resolution of 654.5x(654.5*480/720) = 654.5x436.4 (in that case you maintain the aspect ratio).

There are now two options:
1) cropping the original DV to 720xsomething
2) resizing to 688xsomething (note that 688 and something must be a multiple of 32)

Let's look at the second option. We know that "something" is such that

"something" * 720/688 = 436.4, implying that "something" = 417 (and thus we take 416 since it must be a multiple of 32).

So we have to resize to 688x416 and add borders around it to obtain 720x480.

TMPGEnc source settings (advanced tab):

1) 1:1 vga and center(custom size, enter the size 688x416)

2) the borders will be added automatically

3) stream settings (video tab):
4:3 625 lines NTSC (whatever it is called)

I don't know about the padding stuff. But try this and let us know if you succeed.

[bfavre4]

Thanks. I will try that. By the way, do you know a good site to learn the rectangular and square pixel and aspect ratio stuff for DV and DVD? That software program download site you gave only has that program, not tutorial or anything.

[Wilbert]

"Thanks. I will try that. By the way, do you know a good site to learn the rectangular and square pixel"

See:
"http://www.uwasa.fi/~f76998/video/svcd/faq/#1.1"
and a reference in there:
"http://toolbox.sgi.com/TasteOfDT/documents/video/lurker/pixelaspect.html"

"and aspect ratio stuff for DV and DVD?"

See:
"http://gregl.net/videophile/anamorphic.htm"
and
"http://www.doom9.org/aspectratios.htm"

the bitrate and resolution guide:
"http://www.doom9.org/bitrate_guide.htm#res"

"That software program download site you gave only has that program, not tutorial or anything."

There is a text file in this program (but that's not really a tutorial), and an example:
"http://galileo.spaceports.com/~truman/resize/resize.html"

Good, that it is almost weekend :)

[bfavre4]

Great sites. I will visit them.

But before I saw your reply, I was researching already and came to this conclusion:

I've learned that DV's and DVD's 720x480 (made of 0.9 rect pixels) resolution is not 4:3. The resolution of 704x480 is 4:3. I read that the TV or DVD player reads the video information from the disc and discards 8 pixels from the left and 8 from the right to display 704x480 on the screen. This is called "overscan". So when displaying 704x480, it's 4:3 without the extra 16 pixels. Can you confirm this?

And what is the difference between "overscan" and Title Safe and Action Safe margins? Is overscan cropping MORE off Title Safe and ACtion safe?

[Wilbert]

I've learned that DV's and DVD's 720x480 (made of 0.9 rect pixels) ...

Your TV has 0.9 (10/11) rect. pixels.

... resolution is not 4:3

That's true since it's played back at 720*10/11 = 654.5 with an
aspect ratio of 654.5/480 = 1.3636.


I read that the TV or DVD player reads the video information from the disc and discards 8 pixels from the left and 8 from the right to display 704x480 on the screen. This is called "overscan". So when displaying 704x480, it's 4:3 without the extra 16 pixels. Can you confirm this?

Maybe I'm wrong, but I think this is just coincidence.
16 pixels / 720 * 100 % = 2%, but it is usually (depends on your TV?) more like 10 %.

And what is the difference between "overscan" and Title Safe and Action Safe margins? Is overscan cropping MORE off Title Safe and ACtion safe?

No idea, since I don't know what "Title Safe margin" and "Action Safe margin" is.

[bfavre4]

All right. Thanks.