Function of the PLAY button versus the ENTER button

Question

Hello gang,
I had a quick DVD / DVDSP related question that I've been trying to get a definitive answer for, and I've had great luck and some very helpful responses over in the Final Cut forum so I figured I'd give it a shot.
Anyways, I'm editing some video and authoring a DVD for a group who intend to make an instructional DVD. It's divided into about five chapters and each one begins with some sort of voiceover and text/graphics. In the opening segment of the DVD, there is a voiceover that explains the way to navigate through the DVD and select chapters, etc. etc. The voiceover has already been written and recorded, but I have some concerns about the power they have designated for the "Play" button. Here is an excerpt:
"We use the PLAY button in a couple of ways: to select and play an item that is currently highlighted in a list of items on the screen..."
and also:
"Almost all DVD remotes have a set of buttons that are arranged like a set of arrows (or triangles) pointing to the top, bottom, right and left of the remote control. These keys are used to move the selection pointer on menus presented on the screen. When an item is selected, it is highlighted to distinguish it from the other items in the list that are not selected. Once you have moved the selection point to the item you want, push the PLAY button to actually select and begin playback on that item."
Now here is my concern– I was under the impression that the "Enter" button was typically used to select menu items, etc. I decided to test this on some commercial DVDs I had lying around, and it seems that the Play button does in fact work to select items. I had always assumed it was assigned just one specific role, for example playing the main title on a DVD.
I looked it up in the DVDSP manual and this is all I found:
"A button is selected when the viewer navigates to
it. Only one button at a time can be in the selected state. The selected button becomes
activated when the viewer presses the remote control’s Enter button. Depending on the
button type, highlights or layers are used to indicate each button’s state."
I couldn't find anything regarding the function of the Play button. I suppose my question is this: do these instructions sound okay? Are they universal? Can the Play button be used to select menu items on EVERY DVD player? I am only really stressing about this because this DVD is being targeted towards senior citizens, many of whom have extremely limited knowledge of DVD technology. I'd like to come up with the most universal, simple, and solid instructions for navigation through the DVD.
Okay, thank you in advance. I appreciate any comments or advice you might be able to offer.
PowerBook G4   Mac OS X (10.4.7)  

Answer 1

Ah yes, Jake, but which UOP? Surely, you've seen me address this issue of there not being a Play UOP before?
The project can be set up for Play to be Enter on a very high percentage of players, but it would be good with Christopher’s project to get the announcer to add "and Enter".
The way it works is make sure that the "Still Off" user Op in DVD Studio Pro's Advanced Playback Controls is unchecked. DVD SP started making this default UOP denial in recent versions, which will mess up the Play remote key on a lot of players, including the Apple DVD player.
And it would be good to take notes here Jake, since you do some Scenarist authoring. This Play remote key could bite you big time, if you're not careful (I've rescued two good authors who had trouble with what I'm about to describe; luckily, we caught it before it was submitted for replication).
Still Off, which is what a lot of DVD player manufacturers map their play remote key if they don't directly map it to "Enter", when the DVD player is in infinite pause mode, i.e., the state a cell/program is in when displaying a still menu, causes the menu PGC to execute it's post command area (leave the PGCs still phase).
A check of DVD SP's abstraction layer will show that navigation out of the post command area of all DVD SP's menu PGCs is determined by the current value of SPRM 8, the last selected/activated button. All of DVD SP's menu domain buttons are "LinkTail PGC" commands, so the effect of Operating Play is identical to activating a button with Enter, in the case of Still Off being the trigger.
This can be verified by setting a button command in AfterEdit to jump somewhere directly which is different location than it was set in DVD SP. With the Still Off user op enabled, hit Play on the selected button and find that the original command in DVD SP will execute. But hit enter on the same button, and navigation will go to your test location. This is how it works on many players (you can check it out right in the Apple player).
So it's good for spec based authors to use LinkTail PGC, which most do, on their menu button commands for still menus (in single PGCs), just in case users use Play instead of Enter in those players; or navigation can get pretty wacky! Or, if you don’t use LinkTail for the menus’ button commands, then it would be good to at least provide for code in the PGCs post command area to receive navigation in this case. But LinkTail has lots of other advantages, which is why it's used so much.
With motion menus, Most players map the play remote key to "Enter", well, except the Apple DVD player. It turns the Play remote key to a Pause key during motion, so Christopher’s viewers would definitely be out of luck there.
All that said, the play remote key should not be depended on as the primary for bullet-proof navigation, as you said.
Take care,
Trai