The issues reported in this thread can happen with Windows Vista Media Center, with or without the 2008 Windows Media Center TVPack installed.  The causes behind this are complex and there is not a simple solution that can quickly and fully address all the issues.

The contributors to this thread have touched on factors surrounding this issue which, broadly speaking, fall into 3 buckets:  the broadcast stream itself, the HW configuration and the software implementation – in this case Windows Vista Media Center and the underlying Windows Vista components that comprise the video processing pipeline.  There are aspects associated with each of these that can affect the overall playback experience.  Below provides some background on this particular issue, what is being done about this in future versions of Windows Media Center and what options could impact this now.

This thread has already touched on a cornerstone of what’s causing the symptoms described – frame rates and encoding.  Broadcasters have many options for their content and the Windows video processing pipeline relies on and responds to how the content is authored and flagged.  If the content is authored and flagged correctly, we do not see any playback inconsistencies.  However, if the content is flagged incorrectly or the content is mixed, then the Windows video processing pipeline must gracefully handle this. 

Part of this issue is that some content that is broadcast frequently switches between interlaced (59.94 fps) and progressive (29.97 fps).  We’ve also seen cases where content is incorrectly flagged – i.e. content is interlaced but marked as progressive.  In either case, this causes a hiccup as the underlying Windows video processing pipeline has to respond.  Specifically the GPU deinterlace implementation needs to reset/recover and that can take a few frames.

We know that there is room for improvement in how our video processing pipeline handles scenarios where the content itself or how it is flagged does not fully adhere to standards.  The Windows Media Center team is working to provide a more robust video processing pipeline; however, these efforts are very complex and are geared toward future versions of Windows Media Center.  Given that, we will evaluate if there are portions of this that can be safely implemented on existing versions of Windows Media Center and provided either through Windows Media Center Cumulative Updates or future Windows Service Packs.

We’re also working with content providers, recommending and encouraging better practices with content and how it is flagged.