avformat/dvdvideodec: fix seeking on multi-angle discs

When seeking on multi-angle titles, libdvdnav does not lock on
to the correct sectors initially as it seeks to find the right NAV packet.

This manifests itself as two bugs:
(1) When seeking on the first angle in a multi-angle segment,
frames from another angle will appear (for example in intro
or credits scenes). This issue is present in VLC also.

(2) When seeking during a segment on angle n+1, the demuxer
cannot deduce the right position from dvdnav and does not allow
seeking within the segment (due to it maintaining a strict state).

Correct the issue by switching to angle 1 before doing the seek
operation, and skipping 3 VOBUs (NAV packet led segments) ahead
where dvdnav will have positioned itself correctly.

Reported-by: Kacper Michajlow <kasper93@gmail.com>
Signed-off-by: Marth64 <marth64@proxyid.net>

0 files changed, 0 insertions, 0 deletions