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3D Realtime Playback

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Kevin Cannon
3D Realtime Playback
on Jul 7, 2012 at 6:14:13 am

Hi,

I haven't used resolve for 3D on a mac except to test it... I'm now using it to review 3D Red footage and don't get very satisfying playback (zero grades). Here's the part that perplexes me:

In stereo project 1, I set to 1920x1080 24fps, monitoring 1920x1080 23.98 10-bit. I'm looking at two 1080p photo JPEG quicktimes. I'm getting 48fps (I guess it counts both eyes) playback, from which I gather that the graphics cards, processing, and output card can handle the part of the flow where Resolve works with two 1080p RGB images and sends to 3D output (in dual SDI mode).

In stereo project 2, same 1920x1080 24fps and 1080p monitoring, but two streams of Epic 5K. I start to get 15fps playback (it reads 30fps). Assuming that the issue is debayer speed, I change the debayer speed, but I get the same 15fps if it's full-res premium or eight-res good. I can even change the project to 720p and get 15fps. Changing the monitoring settings still gives me 30fps. Turning off "Display Both Eyes for 3D" goes back to 2D, where I get proper 24fps playback on either eye...

Here's the set-up:
12-Core Mac Pro
24 gigs Ram
GTX120 for GUI
Decklink Extreme 3D+
Cubix Desktop 4 with 2x red rocket and 2x GTX 285
Playing off two internal drives (left from one, right from another)

I would think if the bottleneck was about GPUs or output, that project #1 wouldn't work. If it was about R3D debayering, that going to eighth-res would help...if it was about drive read/write speed that the eyes wouldn't get 24fps in 2D mode.

But I'm stumped. Theories?

Could it be that the drive read speed needs to be higher for one eye of 3D playback than 2D playback? Is there a quick way to tell if Resolve is utilizing both red rockets?

KC

Prehistoric Digital


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Sascha Haber
Re: 3D Realtime Playback
on Jul 7, 2012 at 9:50:39 am

8th res is good for one Epic stream , for two...did you try 16th ?
Two Red Rocket cards would help too :)

A slice of color...

DaVinci 8.2.1 OSX 10.7.2
MacPro 5.1 2x2,4 24GB
RAID0 8TB
GTX 470 / Quadro 4000
Extreme 3D+

ICA Instructor
http://www.icolorist.com/Sascha.html


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Kevin Cannon
Re: 3D Realtime Playback
on Jul 7, 2012 at 1:32:41 pm

Hi Sascha,

There are two red-rockets in there... any trick to tell if they're both being utilized?

KC

Prehistoric Digital


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Alan Gordon
Re: 3D Realtime Playback
on Jul 8, 2012 at 6:07:37 pm

It very well could be the GPU being the bottleneck. In the first scenario there is no scaling going on. It is 1080p straight through. In the second, the GPU must scale the 5k footage to 1080 before playback. And it must do this twice. I would think that 2x 285 should be able to handle a 5k scale each but it is an older card with data lanes being shared with each other AND the rockets.


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Kevin Cannon
Re: 3D Realtime Playback
on Jul 9, 2012 at 6:01:09 am

Hi Alan,

I think you're right that it is an issue caused by the scaling... and either the GPUs are getting data too slow over the shared PCI or are too slow themselves. I will be replacing the GPUs soon and so that will be one test...

I might test playback with some s3d 4K HD set to 1/2 res debayer... that would avoid any scaling by the GPUs, if I'm thinking about it right...

KC

Prehistoric Digital


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Margus Voll
Re: 3D Realtime Playback
on Jul 27, 2012 at 9:54:21 am

Or you could start with small material rendered out as dpx for both streams and try to see if that will work.

Of course faster io needed then.

--

Margus

http://iconstudios.eu

DaVinci 8.2.1 OSX 10.7.3
MacPro 5.1 2x2,93 24GB
GTX 470 / Quadro 4000
Multibridge 2 Pro


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