make alpha channel independent of lifetime of region frame

diff --git a/src/modules/core/transition_region.c b/src/modules/core/transition_region.c
index dfdb83cb0fd31a14dcd2d37c366b170dd29565b1..6fddfa0c59059e0e5bbd358e9b2f31af6b8990ed 100644 (file)
--- a/src/modules/core/transition_region.c
+++ b/src/modules/core/transition_region.c
@@ -113,25 +113,26 @@ static uint8_t *filter_get_alpha_mask( mlt_frame frame )
 
        alpha = mlt_frame_get_alpha_mask( shape_frame );
 
+       int size = region_width * region_height;
+       uint8_t *alpha_duplicate = mlt_pool_alloc( size );
+
        // Generate from the Y component of the image if no alpha available
        if ( alpha == NULL )
        {
-               int size = region_width * region_height;
-               uint8_t *p = mlt_pool_alloc( size );
-               alpha = p;
+               alpha = alpha_duplicate;
                while ( size -- )
                {
-                       *p ++ = ( int )( ( ( *image ++ - 16 ) * 299 ) / 255 );
+                       *alpha ++ = ( int )( ( ( *image ++ - 16 ) * 299 ) / 255 );
                        image ++;
                }
-               mlt_frame_set_alpha( frame, alpha, region_width * region_height, mlt_pool_release );
        }
        else
        {
-               mlt_frame_set_alpha( frame, alpha, region_width * region_height, NULL );
+               memcpy( alpha_duplicate, alpha, size );
        }
+       mlt_frame_set_alpha( frame, alpha_duplicate, region_width * region_height, mlt_pool_release );
 
-       return alpha;
+       return alpha_duplicate;
 }
 
 /** Do it :-).