Memory interface for video output
Normally the video interface logic (video controller) will read from some sort of RAM and output the proper video signals required by the display.  I highly recommend that you don't try to create your own video controller by interfacing some sort of RAM and CPLD to your DSP.  Doing a video controller is hard.  Really hard.

Don't take this the wrong way, but your question is proof that you don't yet have what it takes to make your own video controller.  This is not really a bad thing.  Few people have what it takes.  A senior electrical engineer with 15+ years of experience would probably take 3 months to create, build, and test such a device while working 40 hours a week on it.  

The "correct" way to solve this would be to choose an MCU or DSP that already has a video controller in it.  For example, TI makes some nice ARM Cortex A8 based MCU's that are as fast or faster at signal processing as the TMS320VC5501 for not a lot of more money (compared to other methods of doing this).  This method also does not require extra memory for video (it is stored in the normal DDR3 SDRAM as what the CPU uses).  

Other solutions would require doing things like adding an MCU w/video to the PCB along with the TMS320VC5501.  Or getting an FPGA+SDRAM to do the same function (and then designing that logic).  Both of these solutions are crazy given that the TMS320VC5501 is not that fast of a DSP and you get a huge bang for the buck from the ARM Cortex A8's.  Not only will these solutions cost more, but they also more complex, take up more PCB space and will not operate as well.