Christophe Cholet

Local alpha and IPU overlay

Discussion created by Christophe Cholet on Jun 21, 2012
Latest reply on Mar 19, 2015 by Sudipta subudhi



On the current IPU video stream, I wish to overlay a picture by using local alpha blending technique.

I obtain 3 results:

(local_alpha is enabled)

1- Picture format = BGR24 bits + 8 bits separate alpha ==> Correct blending of the picture.

2- Picture format = BGRA32 bits ==> The picture doesn't appear.

3- Picture format = BGR 32 bits + 8 bits separate alpha ==> The picture is blended but colors are corrupted (i've tried severals BGR or RGB possibilities).


For the cases 2 and 3, if i switch local alpha to 0 and global alpha to 1, then i see the picture (but no more the video stream).


So, i think there's an IPU issue when 32 bits overlay signal and local alpha are used.

Someone can confirm or not ?