No problem with the GPL. I meant flow chart for the firmware. I have attached a simple flow chart to describe the functionality required.

A more detailed flow chart will be provided with error messages and all artwork. I have all artwork in place and licence for it. As you can see the functionality of the player is simplified. I do not need: FM tuner, voice recorder, mass storage, E-book, games, stopwatch, calculator and calendar, I just need the player function and the video function (in a limited way) plus a special menu 3 to select the song.
What do you think about the functionality?
Also I have one more question, the Rockbox firmware is not infringing against Sisvel license rights if used in commercial products? Do I have to buy this one sepparatly?