I have done DSP programming (on the 770, n8x0) and it's a pita - porting code should be reasonably straightforward (once you work out how to plumb whatever code you decide to use into the DSP framework - to get data in and out and work out how the threading and other data passing works).

The TMS320C6X DSPs have an 8bit type at last, so it won't be as painful as it used to be to convert code, but then you have to make sure the codec memory footprint fits in the DSP's available memory (and move different structures into faster or slower memory depending on their usage), and once you've done that, you need to modify the code to use the provided intrinsics, MACs, parallel-isations, etc, make sure the operation scheduling is optimum (probably by re-writing parts in ASM). Once you do all that you may end up with something that can decode 720p in real time.

Once all that is done, it's time to debug. I've not used the current debugging tools, but I hope they are better than the "add multiple printfs" which I had to use. In fact you'll probably find that most people write the code for an emulator which provides an interactive debugger. So this may well be a major headache for you.

It's an interesting learning experience if someone wants to take a stab at it, but make sure you're willing to do some hard graft and for a rather long time. Good luck