Discussion:
[CinCVS] 16:9 from 4:3 ??
(too old to reply)
Bernhard Frühmesser
2006-10-02 14:00:54 UTC
Permalink
Hello,

I have a video with 720x576 with 4:3 aspect ratio, is it possible to get
a 16:9 (Letterboxed) aspect ratio out?

I have set 16:9 in the "Format Dialog", it looked 16:9 while watching in
the compositor, but after rendering it was 4:3 again.

So it it possible at all to get 16:9 out of a 4:3 source matterial?

Thanks,
BF.
Herman Robak
2006-10-02 17:30:57 UTC
Permalink
Post by Bernhard Frühmesser
Hello,
I have a video with 720x576 with 4:3 aspect ratio, is it possible to get
a 16:9 (Letterboxed) aspect ratio out?
I have set 16:9 in the "Format Dialog", it looked 16:9 while watching in
the compositor, but after rendering it was 4:3 again.
Depending on the format, you may have to tell the player that the
correct aspect ratio is 16:9. For mplayer, that would be:

mplayer -aspect 16:9 movie.avi

MPEG files can contain aspect information, which the player should
obey automatically. I think raw DV streams contain aspect info, too.

I do not know whether Cinelerra adds the appropriate aspect ratio
header to output formats that support that kind of information.
This would indeed be worthwhile to test!
Post by Bernhard Frühmesser
So it it possible at all to get 16:9 out of a 4:3 source matterial?
If you want letterboxing, you either have to mask off the top and the
bottom of the image, or scale it down vertically. Both operations are
quite straightforward in Cinelerra.

Generally, letterboxing is not desireable. It is a workaround to
display wide content on 4:3 screens. Modern 4:3 TVs and media players
can do the letterboxing themselves, when they detect that the content
is 16:9. Wasting a lot of bits to encode black pixels should be
avoided, if possible.
--
Herman Robak
Bernhard Frühmesser
2006-10-02 21:50:16 UTC
Permalink
On Mon, 02 Oct 2006 16:00:54 +0200, Bernhard Frühmesser
Post by Bernhard Frühmesser
Hello,
I have a video with 720x576 with 4:3 aspect ratio, is it possible to
get a 16:9 (Letterboxed) aspect ratio out?
I have set 16:9 in the "Format Dialog", it looked 16:9 while watching
in the compositor, but after rendering it was 4:3 again.
Depending on the format, you may have to tell the player that the
mplayer -aspect 16:9 movie.avi
MPEG files can contain aspect information, which the player should
obey automatically. I think raw DV streams contain aspect info, too.
I do not know whether Cinelerra adds the appropriate aspect ratio
header to output formats that support that kind of information.
This would indeed be worthwhile to test!
Post by Bernhard Frühmesser
So it it possible at all to get 16:9 out of a 4:3 source matterial?
If you want letterboxing, you either have to mask off the top and the
bottom of the image, or scale it down vertically. Both operations are
quite straightforward in Cinelerra.
Well, i have been playing around with masking off the top and bottom,
but for some reason the finally rendered file was 4:3 again with no
borders... and i can´t find out why. I have now read the part about
masking in the Secrets of Cinelerra bout 10 times or so :-)

Is there some trick to get the masks rendered too?

Thanks,

BF.
Generally, letterboxing is not desireable. It is a workaround to
display wide content on 4:3 screens. Modern 4:3 TVs and media players
can do the letterboxing themselves, when they detect that the content
is 16:9. Wasting a lot of bits to encode black pixels should be
avoided, if possible.
Herman Robak
2006-10-02 22:27:12 UTC
Permalink
Post by Bernhard Frühmesser
Post by Herman Robak
If you want letterboxing, you either have to mask off the top and the
bottom of the image, or scale it down vertically. Both operations are
quite straightforward in Cinelerra.
Well, i have been playing around with masking off the top and bottom,
but for some reason the finally rendered file was 4:3 again with no
borders... and i can´t find out why. I have now read the part about
masking in the Secrets of Cinelerra bout 10 times or so :-)
What format is your recorded video?

Is it 4:3? Do you want 4:3 video to appear like 16:9 video on a 4:3
screen? Then you have to black out part of the image, which is rather
wasteful.
Why would you want that? For artistic effect; go ahead, put on black
bands, if you like. To match it with other 16:9 content you have,
black bands may be totally wrong, and stretching the middle 432 pixels
out to 576 pixels would be more reasonable. So I think you should
tell us exactly what you are trying to accomplish.

Is it 16:9, and your screen is 4:3? Are you sure rendering letter-
boxed video is the only way to get letterboxed display on the TV?
Otherwise the normal way is to keep the 16:9 image pixel for pixel,
and let the player or the screen do the scaling/letterboxing.
Post by Bernhard Frühmesser
Is there some trick to get the masks rendered too?
I am not sure if I understand the question. However, I would consider
using Cinelerra's mask feature to be overkill here. You could use an
overlay of two black PNGs, or one black PNG with a transparent stripe
in the middle.

A simpler way would be setting the track's size to 720x432, or
whatever height you wanted. Right-click on the track, and choose
"resize track".
--
Herman Robak
Herman Robak
2006-10-02 22:49:08 UTC
Permalink
Post by Herman Robak
What format is your recorded video?
Is it 4:3? Do you want 4:3 video to appear like 16:9 video on a 4:3
screen? Then you have to black out part of the image, which is rather
wasteful.
Some background information about 16:9, dos and don'ts:
http://www.adamwilt.com/DV-FAQ-etc.html#widescreen
--
Herman Robak
Bernhard Frühmesser
2006-10-02 22:48:33 UTC
Permalink
On Mon, 02 Oct 2006 23:50:16 +0200, Bernhard Frühmesser
Post by Bernhard Frühmesser
Post by Herman Robak
If you want letterboxing, you either have to mask off the top and the
bottom of the image, or scale it down vertically. Both operations are
quite straightforward in Cinelerra.
Well, i have been playing around with masking off the top and bottom,
but for some reason the finally rendered file was 4:3 again with no
borders... and i can´t find out why. I have now read the part about
masking in the Secrets of Cinelerra bout 10 times or so :-)
What format is your recorded video?
Is it 4:3? Do you want 4:3 video to appear like 16:9 video on a 4:3
screen? Then you have to black out part of the image, which is rather
wasteful.
Why would you want that? For artistic effect; go ahead, put on black
bands, if you like. To match it with other 16:9 content you have,
black bands may be totally wrong, and stretching the middle 432 pixels
out to 576 pixels would be more reasonable. So I think you should
tell us exactly what you are trying to accomplish.
The source video is 720x576 4:3.

I would keep the video as it is, but a friend want´s it Letterboxed 16:9
and it will be shown via a Videobeamer and not enough it should match
with 16:9 content from real 16:9 source matterial :-(

Here is a picture of the original video:

Loading Image...

And here is a picture of how a friend would want it:

Loading Image...

So Letterboxed and final aspect ration 16:9.
Is it 16:9, and your screen is 4:3? Are you sure rendering letter-
boxed video is the only way to get letterboxed display on the TV?
Otherwise the normal way is to keep the 16:9 image pixel for pixel,
and let the player or the screen do the scaling/letterboxing.
Post by Bernhard Frühmesser
Is there some trick to get the masks rendered too?
I am not sure if I understand the question. However, I would consider
using Cinelerra's mask feature to be overkill here. You could use an
overlay of two black PNGs, or one black PNG with a transparent stripe
in the middle.
Well, i have added a Mask (borders) to top and bottom with which the
video nearly looks like the second photo. But the Rendered file doesn´t
have the borders and i don´t know why.

I will try the "PNG-way" - thanks for the tip!
A simpler way would be setting the track's size to 720x432, or
whatever height you wanted. Right-click on the track, and choose
"resize track".
I have tested this but it cut´s off too much and i don´t have any more
space left for the black borders on top and bottom.

BF.
Herman Robak
2006-10-03 07:43:18 UTC
Permalink
Post by Bernhard Frühmesser
Post by Herman Robak
What format is your recorded video?
Is it 4:3? Do you want 4:3 video to appear like 16:9 video on a 4:3
screen? Then you have to black out part of the image, which is rather
wasteful.
Why would you want that? For artistic effect; go ahead, put on black
bands, if you like. To match it with other 16:9 content you have,
black bands may be totally wrong, and stretching the middle 432 pixels
out to 576 pixels would be more reasonable. So I think you should
tell us exactly what you are trying to accomplish.
The source video is 720x576 4:3.
I would keep the video as it is, but a friend want´s it Letterboxed 16:9
and it will be shown via a Videobeamer and not enough it should match
with 16:9 content from real 16:9 source matterial :-(
http://vi06n235.members.eunet.at//images/Drehtag1_5.jpg
http://vi06n235.members.eunet.at//images/snowdd3.jpg
So Letterboxed and final aspect ration 16:9.
Please read Adam Wilt's DV FAQ about 16:9 ...
http://www.adamwilt.com/DV-FAQ-etc.html#widescreen

...and check out if your friend has 16:9 content that does 16:9 "the
right way" or "the wrong way". If his 16:9 content does it "the right
way", then you are trying The Wrong Thing. REAL 16:9 content does not
have black bars in the video. REAL 16:9 DV must be stretched 33% more
horizontally, or it will look like this:
Loading Image...

...whereas with the correct stretching it will look like this:
Loading Image...

What kind of medium shall the videos be on? DVD? DVDs have aspect
ratio as part of the format. If the player detects a 16:9 aspect
ratio, and knows that the screen is 4:3, it will add letterboxing.

Rendering letterboxing into the video is only appropriate if the
main video is 4:3, with some 16:9 material put into it. This is
because DVD players can't switch aspect ratio during playback.
(they can't switch between PAL and NTSC during playback, either)
Post by Bernhard Frühmesser
Post by Herman Robak
A simpler way would be setting the track's size to 720x432, or
whatever height you wanted. Right-click on the track, and choose
"resize track".
I have tested this but it cut´s off too much and i don´t have any more
space left for the black borders on top and bottom.
So if you leave the project resolution at 720x576 in the Format dialog,
but set it to 720x432 for the track, you don't get a 16:9 image with
black borders above and below? That was what I was expecting.
--
Herman Robak
Bernhard Frühmesser
2006-10-03 15:00:09 UTC
Permalink
On Tue, 03 Oct 2006 00:48:33 +0200, Bernhard Frühmesser
Post by Bernhard Frühmesser
Post by Herman Robak
What format is your recorded video?
Is it 4:3? Do you want 4:3 video to appear like 16:9 video on a 4:3
screen? Then you have to black out part of the image, which is rather
wasteful.
Why would you want that? For artistic effect; go ahead, put on black
bands, if you like. To match it with other 16:9 content you have,
black bands may be totally wrong, and stretching the middle 432 pixels
out to 576 pixels would be more reasonable. So I think you should
tell us exactly what you are trying to accomplish.
The source video is 720x576 4:3.
I would keep the video as it is, but a friend want´s it Letterboxed
16:9 and it will be shown via a Videobeamer and not enough it should
match with 16:9 content from real 16:9 source matterial :-(
http://vi06n235.members.eunet.at//images/Drehtag1_5.jpg
http://vi06n235.members.eunet.at//images/snowdd3.jpg
So Letterboxed and final aspect ration 16:9.
Please read Adam Wilt's DV FAQ about 16:9 ...
http://www.adamwilt.com/DV-FAQ-etc.html#widescreen
I did, really interesting and informative!

Thanks for the Link !
...and check out if your friend has 16:9 content that does 16:9 "the
right way" or "the wrong way". If his 16:9 content does it "the right
way", then you are trying The Wrong Thing. REAL 16:9 content does not
have black bars in the video. REAL 16:9 DV must be stretched 33% more
http://www.nuug.no/pub/herman/lm/mediaspillere/16x9-feil.png
http://www.nuug.no/pub/herman/lm/mediaspillere/16x9-riktig.png
What kind of medium shall the videos be on? DVD? DVDs have aspect
ratio as part of the format. If the player detects a 16:9 aspect
ratio, and knows that the screen is 4:3, it will add letterboxing.
The final Video will be on a DVD.
Rendering letterboxing into the video is only appropriate if the
main video is 4:3, with some 16:9 material put into it. This is
because DVD players can't switch aspect ratio during playback.
(they can't switch between PAL and NTSC during playback, either)
I think i´ll tell him to keep the original as it is as there are so many
close up pictures in the video that if i would Letterbox the video these
close up´s don´t look good anymore.

So far he didn´t care about 16:9 while shooting the video
Post by Bernhard Frühmesser
Post by Herman Robak
A simpler way would be setting the track's size to 720x432, or
whatever height you wanted. Right-click on the track, and choose
"resize track".
I have tested this but it cut´s off too much and i don´t have any
more space left for the black borders on top and bottom.
So if you leave the project resolution at 720x576 in the Format dialog,
but set it to 720x432 for the track, you don't get a 16:9 image with
black borders above and below? That was what I was expecting.
Well, this works within cinelerra but as soon as i start rendering
cinelerra makes the whole box reboot... and i can´t find out why.
This happens as "mortal user" and as well as root.

BF.

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