[mythtvnz] TVNZ DVB-S Playback issues due to variable GOP size

[Steven Ellis]

TVNZ made some changes to their DVB-S transmissions a couple of weeks ago,
at which time they introduced variable GOP sizes into the MPEG2 streams.

On DVD MPEG2-PS streams have a maximum GOP size of 30. For MPEG2-TS
streams over DVB you can exceed this value which can result in much better
compression.

Since they made the change I've noticed that I get occasional playback
issues on the TVNZ channels. This happens on both recordings and LiveTV.
What appears to happen is the video might suddenly speed up and then slow
down over the space of a second or so. Its like the MPEG2 decoder is
confused on how to maintain sync between the audio and video due to the
GOP length.

I'm normally using the "LibMPEG2" decoder with BOB deinterlacing, and I
don't use "Video as the Timebase" as that can result in slightly fast
audio.

Has anyone else noticed similar issues, and if not what video playback
options are you using.

Steve

--------------------------------------------
Steven Ellis - Technical Director
OpenMedia Limited - The Home of myPVR
email   - steven at openmedia.co.nz
sales   - sales at openmedia.co.nz
support - support at openmedia.co.nz
website - http://www.openmedia.co.nz