[pitivi: 3/5] fix bug 634933 - Preview in the Timeline is weird and wrong...

[Edward Hervey <edwardrv src gnome org>]

commit 8521cfe331f51dc6c721c3cf2653f55332bf4842
Author: Benjamin M. Schwartz <bens alum mit edu>
Date:   Mon Nov 29 11:47:53 2010 +0000

    fix bug 634933 - Preview in the Timeline is weird and wrong...

 pitivi/elements/thumbnailsink.py |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)
---
diff --git a/pitivi/elements/thumbnailsink.py b/pitivi/elements/thumbnailsink.py
index 0f51041..e170844 100644
--- a/pitivi/elements/thumbnailsink.py
+++ b/pitivi/elements/thumbnailsink.py
@@ -82,7 +82,11 @@ class CairoSurfaceThumbnailSink(gst.BaseSink):
         b = array.array("b")
         b.fromstring(buf)
         pixb = cairo.ImageSurface.create_for_data(b,
-            cairo.FORMAT_ARGB32,
+            # We don't use FORMAT_ARGB32 because Cairo uses premultiplied
+            # alpha, and gstreamer does not.  Discarding the alpha channel
+            # is not ideal, but the alternative would be to compute the
+            # conversion in python (slow!).
+            cairo.FORMAT_RGB24,
             self.width,
             self.height,
             self.width * 4)