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hi,


Last Saturday I finally put the Optoma GT720 on the ceiling so I can finally sat down and watch it.


Last night I was going to watch A Christmas Coral blu-ray 3D. But the playback stutter quite bad.


My system:

- projector Optoma GT720 in 720p 120hz DLP Link 3D mode

- HTPC Win 7 64bit, ATI 5570, TMT3 with 3D plugin

- connection, 5570 DVI-HDMI to Optoma in 1280x720 120hz for video, 5570 HDMI-HDMI to Pioneer 23TXH receiver for HD audio bitstream


HTPC hardware is a ASRock P43 board, CPU E5300 dual core, overclocked to 3.33G (333x10), 6G DDR2 ram etc.


All other 3D blu-ray I tried played smooth without any issue, including Avatar (Panasonic bundle version), Alice in Wonderland, The Polar Express, The Hole, MJ This is It (3D version), and some Samsung and Pansonic 3D blu-ray demo disc.


Only this A Christmas Coral has stutter problem. I tried overclocked CPU a bit more to 3.66G (333x11) but playback still stutter.


Is it that I need a even faster CPU, or a quad CPU? Or faster display card? Or the problem is TMT3 itself?


Anyone tried A Christmas Coral 3D blu-ray with similar setup? Thanks in advance.


regards,


Li On
 

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Just a shot in the dark, maybe you could try ripping the bluray to your hard disc to see if it helps with the stuttering. My first thought would be CPU isn't powerful enough but you were able to play the other 3D blurays ok so I'm not sure on it. You can't check the CPU usage when playing in 3D mode right?


some questions please. I have a 5770 and maybe planning to do 3D in the future. What catalyst firmware are you using and what glasses are you using with your Optoma?


Thanks.
 

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***This is my understanding of 3D Blu-Ray playback on Non hdmi 1.4 hardware so I might be wrong***


Unlike 2d blurays that can be off loaded to the GPU, 3D blurays rely on the CPU to render them. In the case of an Optoma GT720 projector the playback software (TMT 3) must extract the left and right images from the 1080p frame, as the projector needs these frames sent at 120hz. The new 1.4a HDMI standard sends this 1080p info across at 60hz only pulling apart the left / right frames at the display device.


Due to this additional processing to produce a 120hz video stream I understand the video card cannot help, so the CPU must do this.


In that case it is very possible the stutter is due to the CPU being over worked. One way to check CPU use during 3d playback is to start up windows performance monitor (built into both Vista and windows 7) and have it log CPU use over say 5 minutes. During that time, fire up the 3D movie and let it stutter along. Stop playback then and check that logged graph. You may find CPU use above 90% !


My setup is very similar to yours, Optoma hd66 projector, ATI 5770 video card, but my CPU is an i7, during 3d playback my CPU use is around 20% (this is using TMT 5). If I play a 2d Blu-Ray with the same setup my CPU use is much lower (5 - 7%).



See what performance monitor shows while the movie is playing, it may not be the CPU at all, but its a good place to start checking its use.
 
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