On Thursday 21 December 2006 06:30, Joey Richards wrote:
> Hello,
>
> I'm having trouble with dissolves into static PNG images.  I have a
> simple video with two tracks -- one for the video and another where I
> place PNG title images, etc.  These titles are text on a translucent
> (alpha<1) background rectangle to increase readability.  I'd like these
> to quickly fade in and out to avoid the jarring affect of their suddenly
> popping on to the screen.
>
> I tried this with a dissolve transition at the start and end of each
> region with the PNG image.  The title track is empty between PNG images.
>   The dissolve from an image to a blank region works as I expect -- the
> background box gently fades out.
>
> The transition when the PNG appears does not work correctly.  On the
> first frame as the dissolve begins, a very dark region corresponding to
> the text background box appears and then the image fades in.  This is
> what I'd expect if the alpha is not being correctly interpolated --
> e.g., if it faded from 1 instead of from 0.
>
> In case this was a problem with a transition from nothing to the image,
> I have tried placing a blank (alpha = 0 everywhere) image before the PNG
> title -- no effect, it still pops in black then fades in.  I can get the
> effect I want by keyframing the fade attribute of the track, but this is
> a lot more tedious than just dropping a dissolve onto the clip.

Please create a bug report, bugs.cinelerra.org. Attach a small project that 
shows the problem, along with the PNG (video is not needed).

-- Hannes

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