Re: Some questions

Sun Aug 11 2002, Martin Piskernig wrote:
> Hi,
> 
> first a big Thank You - I bought a DVD some days ago and tried with ogle 
> 0.8.4 - no sound. I then upgraded to a 0.8.5 snapshot - it worked and 
> made me really happy :-)
> 
> My questions are:
> 1. Can you estimate when the DVDTimeSearch and DVDTimePlay functions 
> will be implemented? And is the former function just the latter using 
> the current title?

There are a few ways to do this, it not clear to me which will be better
or for that matter 'the rigth way'.  Need to add some stuff to libdvdread
to get this working too.  So that should probably be the first thing.
Local time searches are easy to do, forward and backwards seeks of
0.5 - 7.5, 10, 30, 60 and 120 seconds (within one cell) can be easily
done.  If one can accept reading a few NAV blocks you can use this to
do a search to an arbitrary time.   Then for Titles there is a time seach
table that list which VOBU to start at for a given time.

The interface is mostly a clone of M$ dvd player/navigation interface.
Look at their developers pages to get some more info.

I don't rembember off hand what the difference for these two are, but
it could well be just that DVDTimeSearch is seeking with in the current
title and DVDTimePlay is to start playing at a certain time withing a 
specified Title.

> 2. The DVDGetCurrentLocation returns some strange time values like e.g. 
> 0:0:81?! Do I have to "normalize" this value to the usual 60-sec/min 
> format (so it's actually 0:1:21)?

It's supposed to be normalized already.  If you can find where this 
happens that would be really great.  (You know that it's hours, minutes,
seconds and frames, right?  Still 81 isn't a number that should appear.

Just figured out whats wrong.  The times are stored in BCD format, but
when I wrote this code I forgot that and so did normal math on them.

> 3. Is there some "event" that notifies me when the currently played 
> title/ptt changes?

No, since there currently isn't any 'events' at all.  I.e. no information
is pushed to the UI.  We've been toying with changing the communication
to use pipes/sockets to enable such things.

> 4. I am thinking of creating DVD "bookmarks" in oKle known from e.g. 
> PowerDVD under Windows. To store the bookmarks for more than one DVD I 
> need a method to differentiate between DVDs. Is there already something 
> deeply hidden in libdvdread for this purpose? I didn't see anything 
> like this in ifo_dump output. So I thought of having a "hash" function 
> similar to the CDDB ID for CDs, which stores some characteristics of a 
> DVD (number of titles/ptts, length of titles etc.) into a hash number. 
> I could implement this only in okle but I thought I let you know it 
> might be nice for ogle to have this in the API.

Yes there have been some amount of discussion about this already.  Nothing
has been implemented yet though.  My current thoughs are on using an MD5
sum over VIDEO_TS.IFO and VTS_01_0.IFO, but leaving room for extending this
without invalidating all the already created IDs if we detect collisions.

> 5. Why is it still not possible to open more than one DVD per ogle 
> execution? Is it so difficult to implement or is it just that nobody 
> bothers to do it because it's a boring/trivial/whatever task? :-)

It's not trivial, but should not be impossible, I think it's boring
though so that's one reason that it hasn't reached the top of the TODO
list.

> 6. Could you put up some place where one can view the CVS changelogs? 
> E.g. a mailing-list ogle-cvs which gets the log when somebody commits 
> his changes to cvs. So one knows what's currently going on.
> 
I'll admit that I have no idea how to set up that.  Any hints would be
appreciated.

-- 
Håkan Hjort