[vlc] Movie alphamask with another movie

[Alex Suter]

On Jan 18, 2008 11:50 AM, Antoine Cellerier <dionoea at videolan.org> wrote:
> That sounds exactly like the mosaic plugin. (see
> http://wiki.videolan.org/Mosaic )
>
> Mosaic input items can use specific filters including one called
> "alphamask". It only supports png images as input for the time being but
> it wouldn't be too hard to change that to using another movie stream.
>
> Could you please be a bit more precise with what you want to acheive so
> I can be a bit more specific? (Documentation on all that mosaic stuff is
> kind of sparse ... it's mainly in the svn commit messages)

Hi Antoine,

Thanks for the response! I was looking at the mosaic code, and was
going to use it as an example, but haven't yet traced out all of the
code paths to figure out exactly how to do it.

What I'm trying to do is mask a movie stream (say, coming from a
DVD) with another movie stream (coming from a mp4 or something
similar on disk). The on-disk mp4 would be a very simple black and
white silhouette. Anything black on the mp4 would be black in the
final image. Anything white on the mp4 would show the DVD stream
in the final image.

I got the alphamask plugin working great, but as you say, it currently
only takes a static png file. I'd love to be able to use a dynamic movie
based mask in its place.

Thanks again for any pointers. It's fun code to pore over.

                           -- Alex