[mythtv-users] MythArchive: Stuck in Chapter Menu
Michael T. Dean
mtdean at thirdcontact.com
Thu Sep 28 22:48:47 UTC 2006
On 09/28/06 13:11, Paul Harrison wrote:
>Rachel Stanley wrote:
>>The only way I've found to get back to the main menu is to hit the "skip to
>>the next chapter" button. Once I get to the end of the title, it returns to
>>the root menu. Or you can go to the chapter menu, select the last chapter,
>>then hit the skip to next chapter.
>>If anyone else knows a better way (or knows how to put a main menu button on
>>the chapter menus), I'd be thrilled.
>The two DVD players that I have access to both have "Top Menu" buttons
>on the remote which always go back to the main menu. Similarly the
>"Menu" button always goes to the chapter menu for the currently playing
>title. If you use xine the default keys are "F1" to go to the main menu
>or "F2" to go to the chapter menu.
>Adding a button on the chapter menu to return to the main menu is on my
>todo list :-)
I think, also, there's some confusion over the meaning of the term "root
menu." Many people are under the impression that the menu that appears
upon initially inserting the DVD is called /the/ root menu. In fact,
it's actually the title menu.
A DVD video disc contains at least one Video ManaGer Menu (VMGM) and
zero or more titlesets. Video is placed in ProGram Chains (PGC's).
PGC's may appear within menus (including the VMGM and titleset menus)
and/or within titles.
Each titleset (I think there can be up to 9) can have any of several
menus. There can be zero or one of each type of menu per titleset; i.e.
a menu could be a root, subtitle (subpicture), audio, angle, or ptt
menu. (Where "ptt" means "part of title", but I have no idea which of
the T's are used for the acronym.) These probably correspond to buttons
on your dedicated DVD-player's remote.
The VMGM--because it's a menu--may contain a PGC, but it is /only/ a
single menu--and it's called /the/ title menu (not subtitle or ptt, just
plain title--titlesets cannot have a title menu). Some DVD player
remotes call the title menu a "DVD menu" or "Disc menu." So, if you're
in the VMGM (whatever plays when you first start the DVD) and you select
the title menu, you'll go to the VMGM title (this can be used, for
example, to skip over legal notices and other "junk" before the
menu--although whether doing so is legal in your area is a whole other
If you're in a titleset and you select the root menu, you'll go to the
titleset's root menu. If the titleset doesn't specify a root menu,
generally the button should do nothing (however most titlesets have a
root menu because it's the only way to call the title menu from a
titleset). If you're in a titleset and you select the title menu, you
/should/ go to the title menu, but if the VMGM is empty (which results
in playing the first titleset's menu upon starting the DVD), you'll go
to the VMGM--which is empty--and continue through to the first
titleset's root menu. In this case, title and root menus result in the
same behavior (even though they're technically different things). This
is one of the main reasons for the confusion about what's considered a
To make matters even worse, the DVD spec actually allows the DVD to
specify commands through a (somewhat primitive) programming language.
Using these commands, DVD designers can actually override the behavior
resulting from requesting different menus. I've actually seen DVD's
that use this to jump back to the root menu in a titleset after
requesting the title menu (making me dig my way back up after digging
down to a video).
Because of this and the fact that there are about a million ways of
designing the menu structure of any DVD, you basically have to figure
out the DVD's internal structure to determine how the menus will work.
And, even then, depending on the DVD in question, it may still behave
differently from how you expect.
So, in summary, there's only one title menu and each titleset can (and
probably does have) its own root menu. Unfortunately, this means the
DVD spec designers chose a terminology that typically has an intuitive
meaning to end users that's very different from its real meaning. And,
even more dissapointing is the fact that the manufacturers of many DVD
players used this terminology (root/title) when making their OSD's and
remotes--generally causing confusion among users (and making them think
that "something must be broken").
Whether a hacker's DVD player (i.e. xine, possibly MythTV's Internal
player) should use the spec's terminology (thereby allowing the hacker
to learn--which is the goal of a true hacker) or should use more
user-friendly terminology is another question I'll leave to the UI
More information about the mythtv-users