When the audio or video format changes, such that a graph stop and restart is required, video play back may hang in a loop changing back and forth between old and new format.
The issue only occurs when using RTSP. It is more frequent in live TV, especially when zapping. Preferred audio language/type aggravate the problem when changing from a stream that contains the preferred audio to one that does not and vice versa.
Skip stepping forward will get you out of the loop until next format change.


h4. Steps to Reproduce
Constantly zap between channels with different video/audio format and/or audio content.

h4. Additional Information
It appears that the issue is caused by the inherent inaccuracy when seeking. When a format change is detected, the graph is stopped and codecs are changed as necessary, then restarted. When using RTSP, this means that the connection to the RTSP stream is closed and a new one is created, seeking to the point of the format change. Because seeking is approximate and can seek before the target position, but most importantly because TsReader does not know accurately the current stream position (it is estimated based on real time elapsed and original start time of the stream, plus current stream duration), occasionally the seek lands before the format change and as a result a new false format change (to the previous format) is detected. After changing to the previous format, the real format change is detected again thus creating a loop.
Singleseat installations and MultiSeat using UNC are not affected because in that case the file is kept open while the graph is stopped and restarted, so no seeking takes place. The stream continues from exactly where it left of.

See this thread: http://forum.team-mediaportal.com/mediaportal-1-1-0-rc-1-2-496/rc2-switching-hd-channels-fails-random-80840/