Hi! I'm trying to compose two videos, and I'm using the alpha plug-in to make the white color transparent. To test the alpha plug-in I'm creating the pipeline with gst-launch. The first test I done was: gst-launch videotestsrc pattern=smpte75 \ ! alpha method=custom target-r=255 target-g=255 target-b=255 angle=10 \ ! videomixer name=mixer ! ffmpegcolorspace ! autovideosink \ videotestsrc pattern=snow ! mixer. and it works great! Then I created two videos with those lines: gst-launch videotestsrc pattern=snow ! ffmpegcolorspace ! theoraenc ! oggmux ! filesink location=snow.ogv gst-launch videotestsrc pattern=smpte75 ! ffmpegcolorspace ! theoraenc ! oggmux ! filesink location=bars75.ogv And changed the videotestsrc to a filesrc and it continues working gst-launch filesrc location=bars75.ogv ! decodebin2 \ ! alpha method=custom target-r=255 target-g=255 target-b=255 angle=10 \ ! videomixer name=mixer ! ffmpegcolorspace ! autovideosink \ filesrc location=snow.ogv ! decodebin2 ! alpha ! mixer. But, when I use the ideo I want to compose, I'm not able to make the white color transparent gst-launch filesrc location=video.ogv ! decodebin2 \ ! alpha method=custom target-r=255 target-g=255 target-b=255 angle=10 \ ! videomixer name=mixer ! ffmpegcolorspace ! autovideosink \ filesrc location=snow.ogv ! decodebin2 ! alpha ! mixer. Can you help me? Any idea what is happening? I'm using GStreamer 0.10.28 You can download the test videos from here: <a href="http://polimedia.upv.es/pub/gst/gst.zip">http://polimedia.upv.es/pub/gst/gst.zip</a> Thanks in advance, Miguel Escriva