How do i activate the alpha channel on an avi inserted into Power.

[Guest]

I know that Powerpoint will accept the alpha channel or transparency of a
gif, because their r irregular shaped animated gifs that come as part of the
office library.

However, i have a black and white animated image of the actual presenter
with their associated voice over that was created as an avi file with an
alpha channel. It inserts just fine into the powerpoint presentation, with
the exception that its transparency channel never gets used by powerpoint.

If i could easily tranlate this file to a gif, that might be a workaround...?

 

[Bill Dilworth]

Transmute that puppy to a GIF.

Movie files are not played by PowerPoint, they are played 'over top' of the
presentation by the system's video player. Your idea of the GIf is, I
believe, the best available solution.

--

Bill Dilworth
Microsoft PPT MVP Team
Users helping fellow users.
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Change org to com to defuse anti-spam,
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[Guest]

Thanks Bill.
Several times, i tried various animated gifs, howeever only the first 2
seconds would play. The gif would then just stop. Perhaps the raason was that
there were too many frames per second ( 25) and at 14-15 seconds ( 320 x 240)
the gif renderer in powerpoint may have been unable to keep up...

I tested these transparent Gifs in a browser and they seemed to work quite
well.

So, i have taken the long way around the problem.

For others having the same problem, one clunky workaround is to layer a copy
of the background image being used in Powerpoint into the same program that
you are using to create your transparent animation. So, if u are using After
affects or Premier or other applications, put/composite a screen copy of the
powerpoint presentation frame behind your animation - the same animation that
has the transparency.
Then create a video specifically of the rectangular region of interest and
import that vicdeo and very carefully layout it over the presentation frame
so that the background of the video matches the background of the
presentation.

Hint: When you select the size of your region of interest, try to use a
width height ratio of 4:3 or something else pretty standard, because if u
dont many of the video comopression codecs may refuse to create a video file
with an odd ratio, and that will leave you with only the option of using
uncompressed video which can be huge.

Region of interest is an aferaffects term which means selecting the area
with a marquee and pottentially cropping it later, as one would do in
photoshop or psp.

 

[Alon Amit]

As far as I know, animated gifs are a very poor substitute to a movie
with an alpha channel. They only offer 8 bits per pixel (256 colors),
and they don't have an alpha channel - only a single a color that can
be designated transparent. (A true alpha channel allows multiple levels
of transparency per pixel).

Also, I've never seen animated gifs used with a size or frame rate that
even approach a "movie". I don't know if there's a hard limit built
into the format, but I'll be surprised if you can do 24fps at 320x200
with an animated gif.

This issue really bugs me, and I think I've mentioned it here in a
couple of posts in the past. I've also sent a feature request to
Microsoft. PowerPoint's handling of video and flash content is
dreadful.

AA