On Friday 30 October 2009 12:59:17 Kapil Agrawal wrote:
> Probably videobox and videomixer may fix it
> -kapil

No, as I stated before in my email, changing the whole frame alpha value is not useful in my case.

Anyway I managed to find the solution myself: the "alpha" plugin works and provides a chroma-key feature that is exacly what I needed.

Now I have another problem: PgmImageSink (in pigment library) refuses to receive a stream with Alpha channel in it.

filesrc -> decodebin -> alpha -> pgmimagesink (doesn't work)

If I put an ffmpegcolorspace, the pipeline runs successfully but the alpha channel is filtered.

filesrc -> decodebin -> alpha -> ffmpegcolorspace -> pgmimagesink
(works but ffmpegcolorspace removes the alpha channel)

Even using capsfilter to force a colorspace with alpha channel won't work.
I think that the problem is in pgmimagesink, but any suggestions are welcome!