Creating a 16x9 file

Paul G
Posts: 9
Joined: Wed Jan 23, 2008 5:59 am
Location: Perth Western Australia

Creating a 16x9 file

Post by Paul G »

I am trying to use a preset which I downloaded from the web, the spinning globe. I wish to render it out as a 16x9 video, Pal. which has a normal 720x576 4x3 aspect ratio. I read that the correct size to do this is to use a custom size of 1024x576. I did this but it appears that the file I created appears to be a 4x3 ratio file which sits upon a larger 16x9 background.

To achieve this it looks as if the background star field has been stretched which would be OK except that the foreground sky does match the background.
When you go to render the file out as an AVI file you are asked for dimensions in pixels as well as being having a box that displays aspect ratio. Most 16x9 files are created using pixels that have an aspect ratio of 1.4568. I could try entering this ration into the box but the custom box for ratio doesn't open. Is know that I could render out the project as 4x3 & then stretch it in my video software, Vegas, but to do this would mean that the globe would no longer be round. Is there any way to produce a 16x9 file that isn't stretched & hasn't gotten the unmatched background?
Thanks in advance
Subquinte
Posts: 3
Joined: Mon Jan 28, 2008 8:08 pm
Location: Germany

Post by Subquinte »

Using a DV-PAL 4:3 source in a 16:9 environment with 720x576 pixels needs a correction factor of 1.4242. This factor must always be used if the line duration is
53,3 usec (DV "pseudo" standard) instead of 52 usec, which is the PAL TV standard. The factor 1.4545 must be used when the source is "only" 704 x 576 pixels . PAL TV needs 704x576 active pixels and must get black bars to the left and the right side, each 8 pixels wide, to get the 720x576 standard (see: ITU-BT-601 rev. 5).
If you have a DV-source, 1.4545 will softly squeeze circles by the factor 1.4545/1.4242= about 1,02%

When I work with COOL3D Pro (not often, therefore I also have sometimes questions about it ...), I only work in a custom 1024x576 environment
with 50fps progressive and export this format lossless to a 4:2:2 YUY2 file .

All generated pictures show the correct AR, circles are round.
Most video-editors accept the 1024x576 format and convert (squeeze) it to anamorphic 720x576.
A very good way is to use AVISynth, which can anamorph and interlace the file (if it will be burned to a DVD later). As a result one gets a DV compatible file which can be edited with other DV-sources without resizing.
If your source (e.g. the spinning globe) is not a nonanamorphic 16:9 format, you first must preprocess it. The only way I know is to use AVISynth.
If the source is e.g. 4:3 PAL, you have 3 choices:

1) Generating a "pillar-boxed" video file

Lets say your source is based on DV (720x576), then you must add 152 rows of black (or any other colour) to both sides of your video.
152 + 720 + 152 = 1024 pixels. This way is lossless but some older MPEG-2 encoders don't like coloured borders (code is blown up), therefore black is the best choice.

2) Crop-resize (=> direct anamorphic output)

The source must be cropped to get 432 lines. Then the cropped video must be resized to 576 pixels. This works only, when the video has been
deinterlaced first (bobbed) because interlaced video cannot be vertical resized without getting errors.

3) Crop only

Crop vertical until you get 16:9. Needs deinterlacing !

Normally one cannot mix 4:3 nonanamorphic with anamorphic sources. One source must be preproccessed first ... but some more expensive software can do it (e.g. Edius ?)

You wrote that the background seems to be stretched. This e.g. can happen, when the globe is 16:9 nonanamorphic and the background 4:3 fullscreen.

Hopefully this can help you a little bit. (Sorry for my bad english...)

- Ray