Frame Buffer (sopc) Issues

Jake,

On the topic of frame buffer bandwidths, I have been trying to do some similar calculations myself recently.

Your method of calculating the bandwidth would be for the average bandwidth. However, peak bandwidths would be a bit higher. Now unless your FIFOs are ridiculously huge, won't the peak memory bus speed required also be higher? It seems to me that a more realistic figure to use would be the average bandwidth for one line of video. For example for 1280x720p50 the required bandwidth would be:

1280/1980*74.25*32 = 1.536 Gbps

Of course, this number is only 4% more than your figure, so maybe I am just being picky. On the other hand, if you are short on block RAM and you are trying to skimp on FIFO sizes, I suspect the required bandwidth would start to approach 74.25*32 = 2.376 Gbps. Multiply that by two for input and output to the frame buffer, and 133MHz x 32 wouldn't cut it at all anymore.

I have only started experimenting with VIP recently myself, so I may be way off in my thinking. I have successfully used the scaler and a few of the other components, but have not even tried a frame buffer yet. Unfortunately, my current board I am testing with doesn't have any external RAM, so it may be a while before I can try a frame buffer.