alpha blend of sample_vpp_drm

Hi all,

I tried alpha blend with sample_vpp_drm, and I find it doesn't work accurately.

 You can view the result here.

• http://youtu.be/2IYki6OvHP4

below is my .par file:

stream=./input_nv12.yuv
width=1920
height=1080
cropx=0
cropy=0
cropw=1920
croph=1080
dstx=0
dsty=0
dstw=1920
dsth=1080
framerate=25
fourcc=nv12

stream=./blend_nv12.yuv
width=320
height=240
cropx=0
cropy=0
cropw=320
croph=240
dstx=500
dsty=0
dstw=320
dsth=240
framerate=25
fourcc=nv12
AlphaEnable=1
GlobalAlpha=128

of course, the input_nv12.yuv resolution is 1920x1080, and the blend_nv12.yuv is 320x240

I want to blend the blend_nv12.yuv on the input_nv12.yuv.