Flattened stills on TV.

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I have been making slideshows with stills burned on a VCD using either Nero 5 (latest version) or WinOnCD 3.7. The results are acceptable , but after a while a slight distorsion in the photographs show started to irritate me and also others were making remarks. Especially when people were displayed and more so if they saw themselves. The problem is a broadening of the pictures, that is the width was stretched. Testing with circles in the center of the pictures showed flattened circles. The flattening of the circles was about 15%. When correcting the width of the pictures to .85 of the original width the circles were shown as perfect circles on the TV-screen. Applying the width reduction to the photographs gave the pictures the appearance the slide whatchers liked. Another observation is that the images of the original unreduced pictures were displayed with black bands on top and bottom of the pictures. When reducing the width to 85% the pictures used the whole 4*3-area of the TV-screen.

First I thought that the broadening of the pictures was due to a misalignment of the TV. However a test image braodcasted by one of the TV stations showed an almost correct circle in the middle. It did have a slightly flattened appearance but that was only a few percent.

I presently have no idea what is wrong. According to the info on http://www.geocities.com/aussie01au/Do-it.html you should have a 4 * 3 ratio of the original input picture, but others said it should be in the ratio of 352 * 288 (or 704 * 576).

Here are some numbers: the size of the original input pictures is 512 * 384 pixels; when burning with WinOnCD I used "match image to visible screen size"; the TV screen has a width * height ratio of 4 * 3; the TV is using PAL; the DVD-player is Pioneer-525; after reducing the width of the input pictures the size used is 435 *384.

Question: What is wrong or what am I doing wrong?

TYIA for your reactions, with friendly greetings, Eppo R. Kooi.

-- Eppo R. Kooi (E.R.Kooi@XS4all.NL), December 13, 2000



I have some comments to make which may help in the end:

1) my site, in the stills web page mentions computer burner based still presentations in the 1st paragraph and then never again because its a NLE based mpeg stream system I have detailed. If the instructions for the stream base images are followed the results will be correct OR all your motion video will suffer the same faults you see in the stills.

2) Burner software generated stills shows are restrictive and you will note I mention a couple of frame sizes which relate to full frame dimensions. I have made only one test presentation so I am no expert but the principal is similar for the source material. Thats also why burner stills are not detailed on my site, I have no hands on, the stream is better.

3) this has been discussed at length on this site several times in the past 15 or so months.

There has always been an argument over the frame sizes for DVD and one school of thought suggests 704 x 576 Pal is correct, most of us with DV camera bases must use 720 x 576. Both are covered by the DVD player spec so there are some conflicts. SpruceUp DVD at least recognises that.

Then comes the DVD player. Some like 704 wide better than others and THIS aspect comes into your stills presentation process. From memory the 525 likes the 704 wide stuff better.

Whilst I think of it, have you tried your presentation on your PC with PROPER software that does the correct expansion, in other words not players like Media player and WinDVD that get it totally wrong. What do your circles look like under those circumstances with SthDVD for example when expanded to fill the 4:3 computer screen?

As is stated on my site, you must start at sizes above those required, if your expanding 512 wide images the quality will be quite low by comparison with those done from full frame or larger.

Here is what I believe you should do as a test. Because this is a burner related process you MUST use final images in either 704 x 576 or 720 x 576 produced from 768 x 576 wide PAL frame sizes to get the quality, ie you MUST get them to the correct sizes for the burner program which is the DV size. You will have to check which is better by doing your little tests with your circles. I have never produced still source material at 352 x 288 but I would use initial sizes of 384 x 288 or higher and feed the burner with 352 x 288. If you have a lot of images below full frame dimensions I would suggest you use that concept, or at least test it - process your source material back to 352 x 288 for the burner in suitable photo imaging software.

Some TV's produce out of round circles from the start, lots of consumer TV's are way out, I have seen circles on other TV's that look as though they were hit with a piece of wood and had a flat on one side. You are very correct to have checked what your TV produces first because you can then adjust what you see in your tests, well done, glad you did not just accept that the TV is correct.

Your circles will never be round on the TV if you use original source images based on ANY DV frame size - 720 x 576, 704 x 576, 352 x 288 etc etc you must start with the equivalent analogue sizes first AND then get them to the DV sizes. DV sources with circles will be round if you play them in Media player and god knows what in WinDVD. You should try 16:9 as an exercise as well, great image format using 1024 x 576 as a base!

-- Ross McL (rmclennan@esc.net.au), December 14, 2000.

There is now a more specific description of preparing stills for VCD, XVCD, SVCD and DVD on my DVD for the consumer page.


-- Ross McL (rmclennan@esc.net.au), December 18, 2000.

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