If you were tasked with operating a commercial DVD player from a computer program, how would you do it?
My company sells a product that does exactly that. We have a couple of different approaches, and they both have major issues:
Get an IR Transmitter, Pretend To Be a Remote Control
Pros: Works with pretty much every commercial DVD player in existence.
Cons: The IR transmitter is another moving part that can (and too frequently does) go wrong. Only allows one-way communication; you can talk to the DVD player, but it can't talk back; you can only tell if it's on or off by seeing if it's putting out a video signal.
Get a DVD Player With an RS-232 Serial Port
Pros: Everything that's "con" with the IR transmitter approach simply goes away. The direct connection is more reliable and allows the code to understand just what the machine is doing.
Cons: Niche market; very few machines actually have an RS-232 port. So, when a manufacturer discontinues a model you've been using, you're left scrambling to find a replacement.
And I suppose for the sake of completeness, I should mention....
Just Use the DVD Drive In the PC
Cons: Boss doesn't like it.
What other approaches are available? I've seen DVD players with USB ports, but the last time I researched the subject, it seemed that was just for playing media stored on an iPhone or the like and not actually a potential control mechanism.
I'm really hoping somebody will say something like "Silly boy, don't you know about the ridiculously common FOO port that allows a home theater system to control the DVD directly? Just get a USB -> FOO converter and you're all set!" But I'm grateful for any options I haven't already considered.