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Considering you have quite a lot of experience building such systems it might not be very useful information but here it goes as this may be useful for others.
The first step in debugging such a system would be to tap the Avalon-ST connections between the cores. With a trigger on sop high, valid high and data = 0x0F you should be able to catch and analyse the control packets flowing through.
You have to bear in mind that the last control packet is the one that matters so placing the trigger on the start of the image packet (sop high, valid high and data = 0x00) might give you a better view of what could be happening. AFAIK, both the deinterlacer and the scaler should be adding an extra control packet into the stream so you should expect two control packets after the deinterlacer and three control packets after the scaler.
In your case, you probably want to know what is coming out of the Clocked Video Input so this could be a first tap point (you may also want to enable the control port to query the core). It might also be worth checking what is happening when eop is sent. It might be difficult to see whether this is an early eop with Signal Tap but you should be able to see how the ready line is behaving at that time.
You may also tap the control packets coming in and out of the scaler, frame buffer and deinterlacer and check in the manual what is the behaviour of these cores when they receive an early eop. For instance the deinterlacer WITH triple buffering will always pad an image packet to the correct length when an early eop is received. So you should not be seeing an early eop at the end of datapath (1.) unless the control packet received was incorrect.
If you strongly suspect there is something wrong with the memory then you could focus both on the Avalon-MM interfaces and on the packets sent by the deinterlacer and/or the frame buffer. Control packets are stored and retrieved from the memory and the behaviour of the system could become quite unpredictable if these are altered, especially if their type switch to the type of an image packet.
vgs
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Thanks.
I suppose these debug techniques would be useful for others. But unfortunately not to me in this case... :(
anyways, thanks for the reply.
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