Early 08 Mac Pro (8 Core) struggling to play HD video

[Pat H]

I just finished editing an HD photo montage and decided to export it as an H.264 quicktime file. I was aiming for a high bitrate since the pictures are in motion, and I ended up with a 1080p30 file averaging roughly 20-40 mbps. I know this is extremely high, but I wanted a blu-ray quality encode.

Playback on my TV via PS3 looks great, but for whatever reason, this file is bringing my 8 Core, 10 gig RAM Mac Pro to its knees. Opening the file in quicktime results in horrible stuttering playback, while VLC will start playing smoothly at first and then crash, citing "computer too slow" as a possibility for the error.

I'm having a hard time believing that this machine can't playback a high bit rate H.264 file. Any ideas? Oddly enough, the activity monitor is showing only moderate usage of system resources during playback. :confused:

[dcpmark]

I think I read it's a VLC problem. Try Quicktime (or QT Pro).

[Dzokayi]

Make sure you're using the latest version of Quicktime (not QT7 - the one with the all dark interface). I understand that it taps your video card to handle the video stream.

I had some 1080p content that wouldn't play in QT7 or VLC, exhibiting the same behavior you described. Opened it with the new QT that comes with Snow Leopard, and everything is peachy. This is with a stock 7300 in Mac Pro 1,1.

Hope that helps.