BSP: Yocto Linux L3.10.17_1.0.0-ga
Refer to "Appendix A mfw_isink Usage" in i.MX 6 Series Yocto Project Multimedia User's Guide, Rev L3.10.17_1.0.0-ga, 05/2014.
Now, I'm trying to test the "isink defines an environment variable VSALPHA to control the video visibility".
But, I couldn't see the changing of transparency of video image despite I changed the VSALPHA value.
$ export VSALPHA=0
$ gst-launch playbin2 uri=file:///home/mount/mp4_mpeg4_aac.mp4 video-sink="mfw_isink axis-left=400 axis-top=400 disp-width=640 disp-height=480"