Building a circuit that capture a screenshot from a HDMI/DVI source and stores it.

Building a circuit that captures a screenshot from a HDMI/DVI source and stores it.

Hello,
I need to build a device that works as a HDMI receiver but it only captures "pictures" of the video stream: it must capture a full screenshot in modality 720p (i.e 1280x720 x 32 bit) at 60Hz and stores it uncompressed on a memory. This memory can then be accessed via USB port and the picture can be read from a PC. I'm having trouble defining the general type of components to be used in this project.
For the HDMI receiver, I would use a chip which is commonly used in HDMI LCD screen (TFP201P). This chip converts the HDMI signal into RGB signal. I really do not know how to interface this chip with the memory... what type of bus should I use? The clock for the HDMI signal has a very high frequency (> 100Mhz) which means I cannot use I2C and maybe not even SPI buses. Same goes for the RAM which should be fast enough to be able to store the picture.
So what type of memory should I use? DDR ? How do I interface this memory with the bus?
Note that I don't need to be able to store the frame with the same frequency as the source video (i.e. 60Hz) A high latency would be OK.
I only need to sort of "Take a picture" of the HDMI video stream from time to time .
Thank you very much to anyone who will be able to help me.

Elektronman

Hi;
I think you should interaface to memory with an FPGA may be. Digital parallel RGB video as input to FPGA, then store to a memory. Then some interface needed to read from the stored image (may as you said may be USB...) Spartan3 might be enough (i am not an expert on it).