[PD] GEM: abnormal performance difference PC/Mac?

vade doktorp at mac.com
Fri Apr 9 20:04:53 CEST 2010

I dont know what the upload path is in GEM, but typically speaking in order to get very high performance video playback on OS X has to make sure to leverage :

proper pixel format for the GL textures, GL_UNSIGNED_INT_8888_REV with a BGRA format, 
make sure to use GL_CLIENT_STORAGE_APPLE and GL_TEXTURE_RANGE_APPLE to minimize unecessary copies of of texture data in the system. You can get large performance increases this way.

see : http://developer.apple.com/mac/library/samplecode/TextureRange/Introduction/Intro.html

Does your machine have an NVidia card in it? Issues have been reported on some developer lists I am on that if you do not supply a the proper format NVidia drivers swizzle the channels in software, not in hardware. There was a thread on the NVidia forums that had discussion about this but I am not sure if anything happened with it.

I personally noticed a ~30% performance decrease in applications playing video to GL on NVidia hardware (from my x1600 to a friends NV8600 mobile) using various apps. 

Im not sure how windows handles this, but I think its safe to say both ATI and Nvidia devote more developer resources to tuning those drivers. Maybe thats part of the issue? Honestly, this is speculation.

Also, Animation is probably not the codec of choice. Its Run Length encoded, so any video that is not graphic (ie, no truly uniform color values ) will converge on being completely uncomrpessed RGB, which will hammer your hard drives.

Photo Jpeg or, these days, Apple Intermediate Codec is the tool of choice for slightly compressed, low bandwidth video. 

Maybe this is helpful? Good luck!

On Apr 9, 2010, at 9:44 AM, Pagano, Patrick wrote:

> Maybe it's the codec? 
> -----Original Message-----
> From: pd-list-bounces at iem.at [mailto:pd-list-bounces at iem.at] On Behalf Of Matteo Sisti Sette
> Sent: Thursday, April 08, 2010 4:49 PM
> To: PD list
> Subject: [PD] GEM: abnormal performance difference PC/Mac?
> Hi,
> I'm working on a patch that has 16 [pix_film]s each one playing back a 
> short loop of video; videos are approx 400x700 size, encoded with 
> Animation and have an alpha channel.
> On a PC with a 2.5GHz dual core (T9300) and Windows, it _almost_ works 
> smoothly: with 10-12 videos it is just fine.
> On a MacBook Pro which has a 2.4GHz dual core it is _much_ slower. Even 
> with only 4 or 5 videos playing, it goes at less than half of the 
> intended 25fps.
> Can the hardware really explain that much difference in performance? Is 
> an intel T9300 that much more powerful than the processor of a MacBook 
> pro? (certainly not because of the 0.1GHz more)? Or the GPU (Nvidia 
> GeForce 9500M GS)?
> Or is there some "software" reason for such a huge performance penalty 
> on Mac OS??
> thanks
> m.
> -- 
> Matteo Sisti Sette
> matteosistisette at gmail.com
> http://www.matteosistisette.com
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