Genlock - master source (DVI) + one framebuffered camera source

Hi,

I'm trying to build a system that can overlay a camerasignal to a DVI signal from my PC . (using Altera VIP)

Here ist my setup so far:

---------------------------------------------------------------------------- MIXER
----------------(A : DVI-source 1080p60) CVI -> ALFABLENDMIXER(layer0) --->|......|
---------------------------------------------------------alpha0_source --->|......|
---------------------------------------------------------------------------|------| ---> CVO (1080p60 same pixclk as source A)
(B:Camera 1080p60) CVI -> CSC -> FRAMEBUFFER -> ALFABLENDMIXER(layer1) --->|......|
---------------------------------------------------------alpha1_source --->|______|


The output signal are not as expected: blinking.. flimmer.. blackscreen..

My first guess is that the problem is lack of framebuffer in the sourceA-path, but its not physical possible due to memory bandwidth!!!

When im replacing sourceA with a TestPatternGenerator i got the intended overlay functionality :).

It should be possible to run with a DVI input with some small adjustings but here im needing help!!!?????

How do i setup the SourceA-path to run without framebuffer?? Using genlock or simpler solution?


I hope someone can give me some hints to reach my goal.

Thanks,
Bertel