I took my most demanding WMV9-HD video (on DVD data disk) into the retailer, and played it on every high end machine in the store, up to p4 3.4ghz HT, 800mhz FSB, Raid 0, 256mb ATI Radeon, nVIDIA etc., and the result always the same...jerky playback, dropped frames, judder.

Blame the GR-HD1! Blame the WM9 encoder! Why this problem?

Finally found this --> http://www.videohelp.com/tools.php?tool=ReClock%20Directshow%20Filter#comments

In a nutshell, your video card does not synchronize its speed with the frame rate of a movie because the clocks used in the video card (to show the video) and in the PC system (to play the video) are completely distinct, thus there always is deviation between them, and then jerkiness is inevitable.

Download the program, then spend 45 minutes reading the lucid help file. You won't believe what you didn't know.

Bottom line...smooth playback on my P4 2.8ghz HT pc, (pushed to the limits!) No more dropped frames, no more judder.

Until you read the tutorial, you'd never believe that the clock source for the DirectShow sound filter is the source for clocking the frame rate of the video, NOT the video card clock. What the program does is replace the DirectShow renderer, and thereafter manipulates the clock speed of the sound codec to bring the video frame rate into synchronization with the video monitor.

Wow, so what steps should we take?

1.) Use the WMV-HD playback tool to help determine if your PC is capable of playing WM9-HD content in 720p.
WMV-HD playback tool (http://www.microsoft.com/windows/windowsmedia/content_provider/film/wmvhdtool_intro.aspx)

2.) Download and install the freeware program ReClock 1.4, and spend 30-45 minutes reading the "Readme1st" file included with the download for a complete background/history of jerky PC playback problems, and how to set ReClock settings to resolve them.

3.) Download and install ZoomPlayer 4.0. This lets you choose the most recent DirectX 9.0 video mixing renderer, VMR9 from a menu.

That's all you need for jerky PC playback, but the next logical step if you have a PC compatible HDTV monitor, i.e. Samsung DLP, Sony GWIII or Panasonic LCD, is to view your WM9-HD files created from your GR-HD1 camcorder footage on the HDTV monitor.

To do that, in addition to the above (3) steps:

4.) Download and install Powerstrip 5.1. This will let you set the resolution of the HDTV monitor as a supported resolution inside your PC graphics hardware.

5.) Sit back and enjoy. I use a Toshiba PC portable hooked up to a 50 inch Samsung DLP HDTV monitor, and view edited GR-HD1 footage in Windows WMV-HD format. It's far more satisfying than simply hooking up the GR-HD1 and watching unedited raw footage.