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Widescreen dv to anamorphic dvd aspect ratio problem. Why?

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Anonymous
April 14, 2004 10:57:13 PM

Archived from groups: rec.video.desktop (More info?)

After converting some 16:9 (anamorphic DV) videos from my Panasonic
PV-DV953 to anamorphic DVD,using either Tmpgenc, or the Pinacle
studio 9 encoder, i found that the aspect ratio of the resulting
anamorphic dvd isn't right. People are shorter (i said shorter) and a
ball look like an elipse.
i've tried all the possible combinations of source aspect ratio and
video streams with these results:

Source Aspect Ratio: Video Stream
-----------------------------------------------------------------
16:9 525 line (NTSC) 16:9 display (people short)
16:9 Display 16:9 display (people short)
1:1 VGA 1:1 VGA (same result as the two first)
16:9 625 line (PAL) 16:9 display (people even shorter)


After a while i found out that if i set the video arrange method to

Custom; Center ; 700 x 490, i get the exact proportion. I even get a
little black bar on the sides, so i lose less image for the overscan,
so that's not a problem. There's some few lines lost on the top and
the bottom too.

I Tried other arrange methods like: Center, Center Keep Aspect ratio,
full screen, Fulscreen K.A.R and so on with no success. People always
short and fat.

Now two questions:

First: Are you guys owners of the PV-dv953 or the new Sonys that does
anamorphic DV as well, having the same problem? Shouldn't the
proportion be right out of the box, since the avi DV is also an
anamorphic 720x480 as the DVD compatible MPEG2 ? (I tried input 1:1
VGA and Output 1:1 VGA with the same results.

Second: I couldn't find the answer to this question even after a lot
of googling. Does this settings (custom, center, 700x490) in Tmpgenc
causes resizing of the image? I don't want resizing, wich would
certainly cause quality loss. I guess that it only sets a flag to
assign the pixel aspect ratio, but i'm not sure. Of course the
resulting mpeg is a compatible 720x480.
I never tested these anamorphic DVD on a widescreen TV. I Tested only
on a 4:3 TV (the player doing the letterbox) and on the PC monitor
with a software player with the same results. I measured the window of
the software player, and the proportion was exactly 16:9, although the
image inside it was distorted before i did the arrange method.

Could someone explain how exactly works the video arrange methods in
Tmpgenc? Does it cause resizing? All of them? Which ones?

I Know that the Anamorphic DV is 720x480 (1.5:1) if the pixels were
square.But the pixels in dv are 0.9, right? What I need is a perfect
16:9 (1.77:1) with a ball looking like a ball and people not skinny
nor fatty.

Sorry for the odd English. I'm from Brazil. Thanks. Waiting for
replies.
Anonymous
April 16, 2004 3:24:22 AM

Archived from groups: rec.video.desktop (More info?)

"Z? Carioca" <joaosilva5435@hotmail.com> wrote in message
news:e299b146.0404141757.1f0b7f25@posting.google.com...
> After a while i found out that if i set the video arrange method to
>
> Custom; Center ; 700 x 490, i get the exact proportion. I even get a
> little black bar on the sides, so i lose less image for the overscan,
> so that's not a problem. There's some few lines lost on the top and
> the bottom too.
>
> I Tried other arrange methods like: Center, Center Keep Aspect ratio,
> full screen, Fulscreen K.A.R and so on with no success. People always
> short and fat.

It sounds like your source video has a 1.78 aspect ratio. The 720x480
resolution in DVD video actually represents a 1.82 aspect ratio. When you
play back an NTSC video at that resolution on your DVD player, the center
area of 704x480 pixels is what gets the actual 16:9 ratio. So what you
probably need to do in TMPGEnc is set the Video Arrange Method to Center
(custom size) and set the target resolution to 704 by 480. There should be
vertical black bars on both sides of 8 pixels each. That's probably not the
only way to do it in TMPGEnc.

> Now two questions:
>
> First: Are you guys owners of the PV-dv953 or the new Sonys that does
> anamorphic DV as well, having the same problem? Shouldn't the
> proportion be right out of the box, since the avi DV is also an
> anamorphic 720x480 as the DVD compatible MPEG2 ? (I tried input 1:1
> VGA and Output 1:1 VGA with the same results.

I'm not an owner of that equipment, but I'm guessing . The camera produces
video in an aspect ratio of 16:9 or approximately 1.78, while standard DVD
video has an aspect ratio of approximately 1.82. The 16 of the 720
horizontal pixels are never displayed on an analog TV. It's some kind of a
consequence of digital to analog conversion. It's not a well-know fact. See
http://www.uwasa.fi/~f76998/video/conversion/ for more details.
__
Alex R
Anonymous
April 16, 2004 3:43:44 AM

Archived from groups: rec.video.desktop (More info?)

"Alex R" <pcalex@REMOVETHIS.hotpop.com> wrote in message
news:GQEfc.149159$K91.374528@attbi_s02...
> "Z? Carioca" <joaosilva5435@hotmail.com> wrote in message
> news:e299b146.0404141757.1f0b7f25@posting.google.com...
> > After a while i found out that if i set the video arrange method to
> >
> > Custom; Center ; 700 x 490, i get the exact proportion. I even get a
> > little black bar on the sides, so i lose less image for the overscan,
> > so that's not a problem. There's some few lines lost on the top and
> > the bottom too.
> >
> > I Tried other arrange methods like: Center, Center Keep Aspect ratio,
> > full screen, Fulscreen K.A.R and so on with no success. People always
> > short and fat.
>
> It sounds like your source video has a 1.78 aspect ratio. The 720x480
> resolution in DVD video actually represents a 1.82 aspect ratio. When you
> play back an NTSC video at that resolution on your DVD player, the center
> area of 704x480 pixels is what gets the actual 16:9 ratio. So what you
> probably need to do in TMPGEnc is set the Video Arrange Method to Center
> (custom size) and set the target resolution to 704 by 480. There should be
> vertical black bars on both sides of 8 pixels each. That's probably not
the
> only way to do it in TMPGEnc.

In addition to that manual setting using Center-custom size, you can set the
Source Aspect Ratio to 16:9 Display, and video arrange method to Full screen
(Keep Aspect Ratio), and TMPGEnc should resize it properly (to 704x480 with
black bars).
__
Alex
pcalex (at) hotpop.com
Related resources
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Anonymous
April 18, 2004 2:29:25 PM

Archived from groups: rec.video.desktop (More info?)

"Alex R" <pcalex@REMOVETHIS.hotpop.com> wrote in message news:<Q6Ffc.141153$gA5.1677983@attbi_s03>...
> "Alex R" <pcalex@REMOVETHIS.hotpop.com> wrote in message
> news:GQEfc.149159$K91.374528@attbi_s02...
> > "Z? Carioca" <joaosilva5435@hotmail.com> wrote in message
> > news:e299b146.0404141757.1f0b7f25@posting.google.com...
> > > After a while i found out that if i set the video arrange method to
> > >
> > > Custom; Center ; 700 x 490, i get the exact proportion. I even get a
> > > little black bar on the sides, so i lose less image for the overscan,
> > > so that's not a problem. There's some few lines lost on the top and
> > > the bottom too.
> > >
> > > I Tried other arrange methods like: Center, Center Keep Aspect ratio,
> > > full screen, Fulscreen K.A.R and so on with no success. People always
> > > short and fat.
> >
> > It sounds like your source video has a 1.78 aspect ratio. The 720x480
> > resolution in DVD video actually represents a 1.82 aspect ratio. When you
> > play back an NTSC video at that resolution on your DVD player, the center
> > area of 704x480 pixels is what gets the actual 16:9 ratio. So what you
> > probably need to do in TMPGEnc is set the Video Arrange Method to Center
> > (custom size) and set the target resolution to 704 by 480. There should be
> > vertical black bars on both sides of 8 pixels each. That's probably not
> the
> > only way to do it in TMPGEnc.
>
> In addition to that manual setting using Center-custom size, you can set the
> Source Aspect Ratio to 16:9 Display, and video arrange method to Full screen
> (Keep Aspect Ratio), and TMPGEnc should resize it properly (to 704x480 with
> black bars).
> __
> Alex
> pcalex (at) hotpop.com


Thanks for the reply. i think that the 720 to 704 resizing is not
enough to correct the distortion. 720 to 688 is enough though. If
there's no other solution but resizing i'll try 688 and keep the 480
lines untouched. (Custom, center, 688x480) I read somewhere it's good
to use multiples of 16 because of the macroblocks. Does it make sense?
I Think that if the trancode was without resizing 720x480 avi to
720x480 mpeg, it would be easier for the encoder because there's no
interpolation, faster and would result in better quality. But is
doesn't work for me, unfortunately. 704x480 is as compatible mpeg for
DVD as well isnt'it? So if i crop the 16 columns in virtualDUB and
frameserve to TMPGEC and encode 704x480 there won't be any resizing.
Maybe it's a partial solution if i can cope with the little
distortion.
Anonymous
April 19, 2004 3:03:12 AM

Archived from groups: rec.video.desktop (More info?)

Z? Carioca wrote:

> Thanks for the reply. i think that the 720 to 704 resizing
> is not enough to correct the distortion.

You are not supposed to _resize_ from 720 to 704, anyway.

720x480 and 704x480 are essentially variations of the same
image format - the 720 pixel variation just has 16 pixels
wider "canvas".

In other words, 704x480 is the middle area of 720x480.
(It is _not_ a horizontally squeezed version where people
would look thinner.)

If you need to convert between these two formats, you either
add 8 pixel black borders to both sides (704 -> 720) or crop
8 pixel columns from both sides (720 -> 704). (You do _not_
resize/resample/rescale/interpolate.)

You might want to take a look at
<http://www.uwasa.fi/~f76998/video/conversion/#conversio...;
for a more detailed explanation.

> 720 to 688 is enough though.

Sounds quite weird.

I have not shot much anything in 16:9 yet so I cannot offer
much insight into what might be wrong with your encoding
parameters, but something is definitely wrong if you first
1) shoot anamorphic 16:9 footage with your DV camcorder and
then 2) have to resize the footage in order to make an
anamorphic 16:9 DVD out of it.

Creating an anamorphic 16:9 DVD out of anamorphic 16:9 DV
footage should be a simple matter of encoding the 720x480
DV images to 720x480 MPEG-2 images - with no need to resize
anything at any point. (Of course, the MPEG-2 stream needs
to be correctly flagged so that the DVD player knows it is
anamorphic 16:9 material.)

> I read somewhere it's good to use multiples of 16 because
> of the macroblocks. Does it make sense?

Yes, it makes sense from the encoding point of view. However,
the idea is not that you should resize directly to multiples
of 16, since this would cause quite coarse rounding errors
and ruin the aspect ratio. If you need to resize video images
for some reason, the first and foremost thing you should
take care of is keeping the aspect ratio correct.

"The divisable by 16" restriction is only applied after
resizing, not during it - in other words, once you have
resized the image the exact, correct amount to keep the
aspect ratio intact, you add borders (or crop the image)
to make the canvas dimensions multiples of 16 pixels (or
whatever the encoder demands.)

--
znark
Anonymous
April 20, 2004 7:37:41 AM

Archived from groups: rec.video.desktop (More info?)

"Z? Carioca" <joaosilva5435@hotmail.com> wrote in message
news:e299b146.0404180929.101af103@posting.google.com...
> Thanks for the reply. i think that the 720 to 704 resizing is not
> enough to correct the distortion. 720 to 688 is enough though. If
> there's no other solution but resizing i'll try 688 and keep the 480
> lines untouched. (Custom, center, 688x480) I read somewhere it's good
> to use multiples of 16 because of the macroblocks. Does it make sense?
> I Think that if the trancode was without resizing 720x480 avi to
> 720x480 mpeg, it would be easier for the encoder because there's no
> interpolation, faster and would result in better quality. But is
> doesn't work for me, unfortunately. 704x480 is as compatible mpeg for
> DVD as well isnt'it? So if i crop the 16 columns in virtualDUB and
> frameserve to TMPGEC and encode 704x480 there won't be any resizing.
> Maybe it's a partial solution if i can cope with the little
> distortion.


To answer your questions, I don't think it makes much difference in quality
if you round to the nearest 16 pixels. What's important is to get the exact
aspect ratio right. 704x480 is not a compatible resolution for a DVD player.
The overall resolution of the final MPEG-2 file should always be 720x480. If
you do any shrinking, there must be black bars around the frame. You
shouldn't be cropping the source video at all. That would have the opposite
effect of what you're trying to do. I don't think there is much quality loss
in resizing 720 to 704.

What happens when you play the captured video on your computer? Is the
aspect ratio correct? If it is, what you can do is take a screenshot
(Alt+PrtScr) of the window in which the video is playing and paste it into a
graphics program (even Paint). Then use the graphics program to measure the
actual dimensions of the playback window to find out what the real aspect
ratio of your video is. Seems like it should be exactly 16:9, but I'm not
sure why interpreting your source video as 16:9 is not working.
__
Alex
pcalex (at) hotpop.com
Anonymous
April 20, 2004 12:16:11 PM

Archived from groups: rec.video.desktop (More info?)

On Tue, 20 Apr 2004 03:37:41 GMT, "Alex R"
<pcalex@REMOVETHIS.hotpop.com> wrote:

>704x480 is not a compatible resolution for a DVD player.

720x480 (576), 704x480 (576), 352x480 (576), 352x240 (288), all
are_standard_ DVD resolutions.
Anonymous
April 20, 2004 3:23:38 PM

Archived from groups: rec.video.desktop (More info?)

"Alex R" <pcalex@REMOVETHIS.hotpop.com> wrote in message news:<9W0hc.20784$hw5.33498@attbi_s53>...
> "Z? Carioca" <joaosilva5435@hotmail.com> wrote in message
> news:e299b146.0404180929.101af103@posting.google.com...
> > Thanks for the reply. i think that the 720 to 704 resizing is not
> > enough to correct the distortion. 720 to 688 is enough though. If
> > there's no other solution but resizing i'll try 688 and keep the 480
> > lines untouched. (Custom, center, 688x480) I read somewhere it's good
> > to use multiples of 16 because of the macroblocks. Does it make sense?
> > I Think that if the trancode was without resizing 720x480 avi to
> > 720x480 mpeg, it would be easier for the encoder because there's no
> > interpolation, faster and would result in better quality. But is
> > doesn't work for me, unfortunately. 704x480 is as compatible mpeg for
> > DVD as well isnt'it? So if i crop the 16 columns in virtualDUB and
> > frameserve to TMPGEC and encode 704x480 there won't be any resizing.
> > Maybe it's a partial solution if i can cope with the little
> > distortion.
>
>
> To answer your questions, I don't think it makes much difference in quality
> if you round to the nearest 16 pixels. What's important is to get the exact
> aspect ratio right. 704x480 is not a compatible resolution for a DVD player.
> The overall resolution of the final MPEG-2 file should always be 720x480. If
> you do any shrinking, there must be black bars around the frame. You
> shouldn't be cropping the source video at all. That would have the opposite
> effect of what you're trying to do. I don't think there is much quality loss
> in resizing 720 to 704.
>
> What happens when you play the captured video on your computer? Is the
> aspect ratio correct? If it is, what you can do is take a screenshot
> (Alt+PrtScr) of the window in which the video is playing and paste it into a
> graphics program (even Paint). Then use the graphics program to measure the
> actual dimensions of the playback window to find out what the real aspect
> ratio of your video is. Seems like it should be exactly 16:9, but I'm not
> sure why interpreting your source video as 16:9 is not working.
> __
> Alex
> pcalex (at) hotpop.com

Ouch! You're right. To crop out columns will cause the opposite
effect. Now i realized it thinking about it. I'd have to add colums.
But the 688x480 solution is working for me. At this point i suspect
that the camera doesn't deliver the aspect ratio it promisses. The
distortion is something about 5% to 7% . I even drawed a graphic with
16 columns of squares of one inch and 9 lines of squares and put a
circle iside it. I can get a perfect circle if i do the 688x480 trick.
Of course i set up my monitor so the window of the software dvd player
is exactly 16:9. But should the window be 16:9 (1.777) or 1.85:1?
I'm sure the distortion doesn't have anything to do with the 720 to
704 resizing or 1.85 versus 1.77 because this would cause 2% to 3% of
distortion and i have about 5% to 7%
If you have any interest, i can email you some frames of the original
avi file of this graphic, or even 5 seconds so you can test yourself
with tmpgenc.
After some googling i found a message of a guy who does wedding videos
professionaly that he got complains of some clients that people looked
short and fat. I bet he's got the same problem that i have.
Anonymous
April 23, 2004 11:02:41 AM

Archived from groups: rec.video.desktop (More info?)

"Z? Carioca" <joaosilva5435@hotmail.com> wrote in message
news:e299b146.0404201023.4fe7e540@posting.google.com...
>
> Ouch! You're right. To crop out columns will cause the opposite
> effect. Now i realized it thinking about it. I'd have to add colums.
> But the 688x480 solution is working for me. At this point i suspect
> that the camera doesn't deliver the aspect ratio it promisses. The
> distortion is something about 5% to 7% . I even drawed a graphic with
> 16 columns of squares of one inch and 9 lines of squares and put a
> circle iside it. I can get a perfect circle if i do the 688x480 trick.
> Of course i set up my monitor so the window of the software dvd player
> is exactly 16:9. But should the window be 16:9 (1.777) or 1.85:1?

The display area of the DVD player window should have an aspect ratio of
1.82:1 (approx. 872x480). I'm not sure why you need to specifically set up
your monitor for that.

> I'm sure the distortion doesn't have anything to do with the 720 to
> 704 resizing or 1.85 versus 1.77 because this would cause 2% to 3% of
> distortion and i have about 5% to 7%
> If you have any interest, i can email you some frames of the original
> avi file of this graphic, or even 5 seconds so you can test yourself
> with tmpgenc.
> After some googling i found a message of a guy who does wedding videos
> professionaly that he got complains of some clients that people looked
> short and fat. I bet he's got the same problem that i have.

Well, you seemed to have solved the problem. You're probably right about the
camera not delivering a true 16:9 aspect ratio.
__
Alex
pcalex (at) hotpop.com
!