Originally Posted by QQQ
As a broad generalization the pro is always going to prefer serial. If someone is using IR on a product that could be controlled via serial (AND they have a serial port available) it probably means that either the serial protocol is seriously flawed (which does happen from time to time) or someone is being lazy or worse. IR is easier for most people so that should pretty much tell you all you need to know. Oh, there is another reason. Sometimes that so-called serial port doesn't actually do anything :). .
I'll disagree, sort of, at least with respect to why I sometimes do not use serial to control a DVD. It's not laziness nor is it from lack of ability. It depends on what I need to happen and it also depends on the cost of the serial port. There is an assumption that jobs do not have some limitation on cost or that cost does not drive some engineering decisions. Even seemingly big budget jobs may reach the point where engineering trade offs occur.
If the device has a rear IR jack and discrete IR codes it is identical to one way serial via RS-232. Even when some serial ports work they may not offer all that much more than discrete IR in terms of control. Panasonic plasmas, Sim2 projectors, the list could be quite long. Finally what if a have a processor with only 3 serial ports and I need the 3 that I have for the lighting system, the CD server and the surround receiver. Might it be something other than laziness to choose to control the DVD with discrete IR via a rear IR jack, such as is found on Denon and Integra?
Finally, what will you do with the information programmaticly? If you intend to turn on the system and switch inputs automatically simply by putting a disc of some type into the DVD player then it makes sense. If all you are going to do is send commands from a one way remote it may not. Is a serial port worth having to display transport feedback? How about the ability to display disc type on the touch panel? Determine power status? Maybe. But I've found that there is little information, save for power status, that is of any importance to me or a client in most DVD players' protocols. If I have the extra serial ports I'll use one on a DVD player. If not I may not view the price of the additional ports as money well spent. My opinion and QQQ is not necessarily wrong in thinking it essential. My systems are not usually as large as his nor do they have his average budget.
Ultimately my decsion is based upon the cost of the serial port ( or its availability ) or whether it will provide something desireable for me to use in my logic or offer the client on the touch panel. I don't get information as to where the disc begins so I can jump there. I don't get aspect ratio information. So I don't think controlling a DVD via discrete IR and a rear jack much of a trade off or such a poor engineering decision.