DaVinci for Transcoding, thunderbolt NVIDIA 4000 thoughts?

[Adam Howden]

Howdy All,

I'm looking at a transcoding option that's more powerful than my Mac Pro but not as expensive as a Red Rocket set up. I'm thinking about buying a Sonnett Echo Express/Pro and putting a GPU like a NVIDIA 4000 or similar running on a macbook pro.

Does anyone have any real world experience with this set up with regards to transcoding times or any other similar cheap/mobile options?

Thanks for your thoughts

 

[Tom Gleeson]

Adam,


The NVIDIA 4000 card will speed up Resolve but will do nothing for debayering the R3D files as this is not a GPU process. You will be bottlenecked. I understand the R3D debayer is done by the CPU. Not sure there is an easy way out of this apart from a Red Rocket card. I bought a battle tested RR card a couple of years ago and its the best $3,500 I have spent. Painful yes but well worth it.


Next year Apple should release a Mac Tower replacement and we may see some serious computing horsepower but by then we will have to be decoding 6K files.

 

[Tom.Wong]

I was under the impression that thunderbolt on the mac side doesn't recognize gpu. I don't think that's really changed, plus there would be severe bottleneck issues with thunderbolt bandwidth.

and gpu debayer with resolve full premium quality in resolve with a quadro 4000 will give you 1.5 fps to 2.5 fps or so. I've had to run r3d through resolve without a rocket before with just a quadro 4000 in my tower. it was really slow.

 

[Jeff Kilgroe]

Tom and Tom, you're both correct. The GDI/graphics layer in OSX is not "Thunderbolt aware", you can't plug a GPU card into a Thunderbolt expander. Well, you can, it just won't do anything, the drivers won't see it. Perhaps this will be addressed at some point in the future. It does work under Windows, though.

The decompression of the wavelet structure is what takes all the massive computing resources and that is performed entirely on the RED Rocket and/or CPUs. It's not something that the GPU can assist with. Any GPU acceleration comes after the decompression of the wavelet/R3D data. For typical transcodes with simple color tweaks, GPU acceleration isn't going to offer a whole lot as the bottleneck is still going to be the wavelet decoding. Debayer is another process that happens after decompression and it's a common misconception that it is what hogs all the resources, but it's only a relatively smaller piece of the CPU resource pie.

Best solution here is a faster computer. If the intent of the transcodes is to create proxies for editing and to conform to the R3D's later, then you really don't need anything that special. You can transcode from a lower resolution decode setting and it can go pretty quick.

 

[Adam Howden]

Hey Tom, tom and Jeff,

Thanks for your thoughts, that helps a heap. so am I right in thinking that a Red Rocket in an Echo Express would provide an accelerated transcode? Or should I just stop faffing about and stick it in my Mac Pro?

 

[Tom.Wong]

i've done extensive tests, if you are using RCX, and rocket. you get identical transcoding speeds from thunderbolt pci expander as inside a tower. i have NOT done any tests with a rocket and resolve on macbook pro yet. but even using resolve on my tower, with a one gpu for cuda acceleration config and a rocket in a 4x slot and a fast raid, i'm not getting real time with resolve at premium debayer. than again, at 5k. most you are getting out of rcx is maybe 20 fps or so. if you start stacking color, i drops to somewhere between 4-15 fps depending on how much you are doing in resolve.

if you want speed, rcx is one of the best bets. free from red, and performs the same in transcodes no matter how much you modify the image with a rocket. all most likely because everything is metadata based.

so rocket + sonnet + macbook pro with thunderbolt will give you equal transcodes speeds as with a tower.

i essentially use a tower for much more additional horsepower. faster bigger raid in the mix. use of software like Scratch Lab, and pure connectivity of ethernet, fw 800, and additional transcoding i need to do outside of r3d. cause it's very common not to just have a RED on a shoot and having to process stuff like go pro, dslr, etc. for b roll or other things.

 

[Adam Howden]

Thanks TW,

You may not be able to answer this but it'd be great if you could; What kind of transcode speeds to say 1/4, 1/2 and full debayer 1920x1080 ProRes are you getting fps wise?

 

[Tom.Wong]

i'm haven't been able to do the test yet, but it used to be, when you're exporting with a rocket, you are doing a full debayer all the time, no matter what your settings are. not sure if that's changed.

 

[Bob Gundu]

I believe the rocket always debayers at full res. it's realitime using a MacBook retina, sonnet, and red rocket.