System Register setting, SPRM2 default value

[brucy]

I will produce my own DVD and start getting familiar with Maestro (before I used Impression). I do have 2 questions:

1. I use several Sub-Pic streams for different languages in combination with sound track infos. So I do quiet a bit in programming command sequences.
For switching on/off languages with/without soundtrack info I check the value of SPRM2. It has a default value at beginning set by default (usual value 62). The problem is if I switch of a subtitle stream (SetSTN St(2-Off) for example) the value jumps to 0 and not to the default value from the beginning. How Do I force the SPRM2 register to get the default value again (here 62)

2. I want to check if the subtitle Menu will be selected from the main menu or from the movie. As I want to use "resume" to jump back to the movie when the user decides to select a subtitle while the movie is already playing or use "jump to main pannel" if the user selects it before he started the movie. What SPRM is the best to check?

[Teariz]

brucy: I can't answer #1 because I don't fully understand the properties of the sprm2 register, but as for #2, what I've done in the past (in dvdlab) is set aside a GPRM register that I won't use anywhere else in the whole program, at the beginning of any menu or movie (except the setup menu for obvious reasons) set that gprm register to a unique value (think of it like you would a primary key in a database) -- when you exit your setup menu simply have it transfer itself to a seperate script, and in that script you can decipher the value of your gprm register and LinkPGCN to the right place!

Hope this helps!

[CirTap]

brucy,
here's a list of SPRMs in case you don't have one:
http://www.mpeg.org/MPEG/DVD/Book_B/Intfunc.html
As Teariz proposed, use GPRMs to store initial values for later, e.g. in the FirstPlay PGC make a backup of the SPRMs you need. However, the audio/subtitle defaults (or last choosen values) may be still available during the "session" in SPRM16-SPRM19, so you may compare your "backup" GPRM or the current language with one of them, but I'm not really sure about their life-time :)
I know nothing about Maestro, but I presume there'll be some GPRMs it uses for it's own features, like DVD-lab "reserves" GPRM 10-15, so try to stick with a few unused GPRMs for your own code. You may need to compare and reassign the language SPRMs in every menu. Easiest way to do this is to have a dummy in the VMGM that has all the code to do this, then in each menu's PRE commands jump to the VMGM, have the values set, then return to the initial menu.

Hope this helps.

have fun,
CirTap

[Cheesus]

Question # 1. I don't think you can get the registry back to 62, it is a startup value for a DVD and essentially means (I think) that no subtitle streams are active. 0 is the correct value for subtitle stream 1 being turned off. 64 is corresponding value for stream 1 being on. 1 is the value for subtitle stream 2 being off, 65 on etc.
So if you press the subtitle button on the remote when the value is 0 the DVD player knows to turn on stream 1. If 62 is in the registry, again I'm not absolutely sure about this, the DVD player will select the subtitle stream language that has been assigned by the user in the DVD players setup i.e. if it's Spainish the DVD will display Spainish.
I read something about this a while back but my memory isn't great so I hope I'm not talking out of my arse with regards to 62. Anyway the first part of my answer is correct, so setting the value to 0 should be valid.
Edit
Turns out I was sort of talking out of my arse. 62 indicates subtitles disabled. 63 (Dummy stream) will try to match to the players default subpicture language setting.

Here's a thread about resuming

http://forum.doom9.org/showthread.php?s=&postid=374473