[DVDnav-discuss] [PATCH] fix dvdnav multi-cell menus

[Steaphan Greene]

On 10/06/2011 10:01 AM, Dominik 'Rathann' Mierzejewski wrote:
> On Thursday, 18 August 2011 at 18:07, Steaphan Greene wrote:
>   
>> As previously sent to mplayer-dev-eng, but with a separate version not
>> including any white-space changes (both attached patches are otherwise
>> identical):
>>
>>
>> Many DVDs with long menus (interactive DVDs or DVD "games" often treat
>> the entire "movie" as a menu) don't work correctly in mplayer's dvdnav.
>> As soon as they change to a new cell, the DVD stops working - It just
>> drops the audio and corrupts the video by, I believe, playing the
>> previous video chunk over and over.  The navigation controls continue to
>> work, though.
>>
>> The problem seems to be that when a new cell is encountered, the dvdnav
>> code indicates it should wait for sync with the application.  However,
>> the code does not actually advance to the next cell (it assumes this
>> case is hit only with still frames, even though the condition also
>> catches the case of cell-changes within menus).
>>
>> Also, once the code to advance to the next block is enabled, by fixing
>> that condition, it still fails in the same way.  This seems to be
>> because the "wait_sync = 1;" is a terminal condition here.  Again, it
>> assumes this is for still frames only and is waiting for the next still
>> frame to be selected (which sets sync_wait back to 0).
>>
>>
>> The attached patch fixes both of these issues, and I have tested it
>> extensively (always with my MPEG2 sync patch, of course) with both
>> normal, and interactive DVDs, and including several examples of actual
>> still frames.  It seems to solve the problem and cause no other new ones
>> that I can find.
>>
>>
>> Of course, I could be wrong about all of this (but I don't think so).
>>     
> Could someone test/review this?
>   

Well, I can confirm that this bug still exists in the current SVN, and
this patch still works to fix it.  I've also been using this modified
version of dvdnav & mplayer for a while now, and have seen no bugs in
dvd playback that weren't there before applying this patch.

Of course, I am the original author of this patch, so if anyone else can
back me up on this (at least, that it doesn't cause any problems for
anyone else), I'm sure that would go a lot farther.  I have, for
example, only tested this on NTSC DVDs (which are all I have).

One thing that does concern me about this patch is that mythtv seems to
use the same dvdnav code, but does NOT show this same bug.  Does this
indicate that it is mplayer that is not properly handing this case?  If
so, I will re-target my efforts back to mplayer.

Otherwise, if there is any way this could get into the upcoming release
version, that would be nice.  But, if it's too late at this point, I
understand.  I would give more details about which DVDs exactly show
this bug, but, unfortunately, I live in the U.S., where I apparently
don't have the right to view my own movies.  So, I don't want to draw
the attention of any of the publishers of the movies I am using for
debugging or testing all this.

Thanks.

P.S. - Note my change of e-mail address from my previous postings.

-- 
Steaphan Greene <steaphan at gmail.com>
Lecturer, Computer Science, Binghamton University
GPG public key: http://www.cs.binghamton.edu/~sgreene/gpg.key.txt