Yeah, generating NTSC and other analog video signals is a pretty common use case for our line of Signal Generators. What board do you have? We even have a software toolkit for creating the analog NTSC signals suitable for downloading to your device. See link.
Looks like I pasted a few extraneous characters...
You can use our video toolkits to create the NTSC analog signal and then save it to a binary file in Windows. Then you can copy that to the LabVIEW RT system and load from file over there. The NTSC signal creation does not have to happen on the fly in the LabVIEW RT system if you already know what they have to be ahead of time.
I'm not sure if the analog specs on the 5412 are good enough for NTSC, you'd need to verify that.
Oops, should've made one longer post.
Can I evaluate the VideoMaster Generator software? I installed from this link:
And the help shows a gui that I can't seem to find.
I could be wrong, but if I remember right, a single frame of NTSC is 1/30 seconds long and you need about 40 MS/s to generate NTSC. At 2 bytes per sample each frame is roughly 2.6 MB.