Two Avalon ST Interfaces comparison

[Altera_Forum]

Hello all, 

 First, I'm sorry if this is not the right forum to post such question !  Second, I desperately need your help !  I'm trying to compare two avalon streaming interfaces (one output from a vip frame buffer and the other from a scaler) with the same resolution ! My problem is how to make my component receives both frames at the same time (make both startofpacket signals asserted at the same time) ? Logically the scaler source (or my custom component 1st sink) should control the other sink (from frame buffer) but I couldn't make that happen !   Any suggestion would be appreciated !  PS : Can I modify the alpha blending mixer behavior to make it compare the 2 sinks ? Or is there any explanation on how does it behave ?   Thank you

[Altera_Forum]

For 1, you need to have both Avalon sinks in the same clock domain if you want to compare the signals. You can do this in SOPC Builder/QSys by using a dual clock fifo instead of a single clock fifo. 

For 2, yes you are right that it makes things more complicated. You must have the same frame rate if you want to compare the two streams, so you will have to drop some frames on the fastest stream.