OSD questions

The DVSDK software we provide with DM355 includes Linux drivers that exercise the OSD hardware.  In particular, the frame buffer driver often referred to as FBDEV; since this is an standardized Linux display driver, the APIs are part of the Linux frame buffer driver APIs.  You can look at the root directory of the Linux kernel (where Linux drivers reside) for a 'Documentation' folder; that should have enough information for you to become familiar with frame buffer API.  In addition, you should be able to find more information on the Internet. 

Finally, the DVSDK also provides example applications (see demos folder) that shows you how to make use of these Linux driver APIs.

The application note below may be of some help, it was written a while back for DM644x but it still mostly applies to DM355. Essentially all you have to have is a image file in the proper format which you can copy into the OSD frame buffer and you can have a simple OSD in place within minutes.

http://focus.ti.com/general/docs/techdocsabstract.tsp?abstractName=spraad7

Since you mentioned you are a newbie, the App Note Bernie mentioned above is probably the easiest way to exercise the OSD (no need to write sample program or know FBDev APIs).

Under Linux, character type driver such as FBDEV can be used in a similar way to files (support read, write, open, close, and ioctl functions), hence Linux commands such as the one described in the App Note are actually calling these common character driver APIs to exercise the OSD (avoiding the need for user to write program).  However, once you get passed this, and you want to write your own application, then the demos and documentation I mentioned in my first post will become useful.

Also, if you are new to Linux and want a good resource for learning how drivers work in general, see the following online book (free): http://lwn.net/Kernel/LDD3/

Thanks for the input