playback of HD content sometimes picture stalls ...

[Phat J]

Hey everyone
I use my computer as a HTPC, and I was watching Planet Earth in H264 720P and the video freezes up temporarily on scenes with a lot of detail in it, like a zoom-out showing thousands and thousands of birds.
It's strange because any other HD movie I have with high motion scenes doesn't lag at all.
I'm trying to determine the source of the problem.
My setup:
CPU P4 3.2GHZ
1GB RAM
nVidia GeForce 7600 GS 256MB
Video is H264 720P, it uses AVC as a decoder.
It's being output to a TV via HDMI/DVI from the video card.
Tried VideoLAN and Media Player Classic, both play it back the same.
And I'm playing the videos from the hard drive, not a disc.

Is there anything I could tweak with performance settings or drivers, or what would I need to improve hardware wise? The latest thing I got was the new video card last fall, as I fried my old one.
The rest of the setup is nearly 4 years old, actually I was amazed it plays HD as well as it does.

Any input is appreciated, thanks in advance.

[Baldrick]

Install a newer version of ffdshow and enable h264/avc and play with mpc. If it wont help you can try Coreavc (disable h264 in ffdshow first) as h264/avc decoding.

[jagabo]

It sounds like your CPU can't keep up with the decoding -- not surprising for a 3.4 GHz P4. ffdshow's h.264 decoder is single threaded. CoreAVC Pro's decoder is multithreaded. Your P4's hyperthreading might give you enough speed when using CoreAVC. Otherwise you're looking at a CPU upgrade.

You might also try disabling the deblocking feature of either codec.

[edDV]

P4 3.2GHZ, 1GB RAM and nVidia GeForce 7600 GS 256MB
are all marginal for full quality 720p h.264. Planet Earth is a worse case for detail and motion (mostly helecopter or airplane shots).

For best picture with that gear, go for MPeg2 and larger files (~12-18Mb/s).