The current code turns of PTS tagging as soon as a match is found. But depending
on picture reordering, there may be later frames which still have the tag. The result
is that most likely the highest bit is set which makes the PTS values large negative
numbers which cause a clock error and make streams unplayable.
To fix this issue, a stable counter is introduced. The two passes of PTS tagging are
now switched after the tag has been seen stable for 100 frames. This should protect
us from picture reordering issues.

--HG--
extra : transplant_source : I%2A%BBi%A5nb/%5E%12%9Ay%7B%BAj%7D%0B%16%0By

This covers the internal snapshot and the version in Debian lenny.

But as PTS values are stored in FFmpeg's decoder, there is no way to reset them to 0.
Therefore PTS tagging has been introduced. At discontinuity a tag is generated and
applied to all new PTS values. Any returned PTS value is checked for this tag and
outdated PTS values are reset to 0. When the tag appears on returned PTS values then
tagging is reset.

Attaching buffer PTS, which are in decoding order, to decoded images is
simply wrong. FFmpeg meanwhile provides a way to pass PTS values through
its decoder too. As a result they get reordered to display order and can
be attached to the decoded frames.