On Sat, 30 Sep 2006 00:53:48 +0200, Bernhard Frühmesser <[EMAIL PROTECTED]>
wrote:
On Fri, Sep 29, 2006 at 01:55:04AM +0200, Herman Robak wrote:
Now, how about having a close look at the result, and figuring out what
the problem is? Then file bug reports. I would certainly like a more
capable titler.
...
Ok, i just used a small part of the Title and created a DVD image file
about 7MB. If possible watch it on a TV screen and or on a LCD Monitor
(also a laptop screen). It looks worst on an Apple laptop if you watch
it with DVD Player and on a TV screen with a stand alone DVD Player (i
tested it with 2 different DVD players - philips and jvc).
The file is available at:
http://www.fruehmesserkeg.at.tf/images/Title.img
(or failing that, here:
http://vi06n235.members.eunet.at/images/Title.img)
That does not look jerky when I view it unscaled (each video pixel
displayed as one screen pixel) on my laptop. But it does flicker
on the horizontal edges when I switch to fullscreen.
I noticed that the text had some hairlines that were so thin that
they almost disappeared. Sharp lines that are thinner than 2 pixels
will flicker easily when moved. On an interlaced screen with low
refresh rate, like at TV screen, this problem will get much worse.
Cinelerra's titler does nothing to protect you against the quirks
of raster screens. Your scrolling title would look quite nice on
a film transfer, but will certainly not work well on TV.
So what should you do?
Firstly, use fonts without thin hairlines. Secondly, apply a slight
vertical blur (radius 1.5 or 2 pixels) to get rid of the flicker on
the sharp horizontal lines. You will have to put the title on a
separate video track to apply effects on the titles only; that is
easy.
Secondly, if you want to use as little blur on the titles as
possible, you have to use one of the handful of "safe speeds" for
scrolling. That is, the text _has to_ scroll an even number of
pixels per frame. If the frame rate is 25 fps, then 50 or 100
pixels per second is OK. Other rates will cause the letters to
change shape slightly between frames, as they will not produce
exactly the same raster pattern. Some of the changes in raster
alignment are more noticable than others, hence the "jerks".
If your titles had moved at 50 fields per second, your choices
of good scrolling speeds would have been very limited; the slowest
good speed would then be 150 pixels per second. (it takes some
drawings of rasters and scan lines to explanain)
Final words: Cinelerra's titler is under-featured as a TV titler!
You _need_ a good, thick, outline; not a drop-shadow. You also
_need_ sensible presets for vertical scrolling, and a sensible
amount of vertical blur. You can accomplish all of that manually,
but you should not have to.
--
Herman Robak
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