Colour grading Mac vs PC

When I decided to set up a little grading system a while ago, I started with a used iMac which someone had offered to me at a good price. I realised that if I invested in a really good monitor to go with it I could actually do some professional level grading from home with only a minimal investment (compared to the cost of a traditional grading suite I was used to in London!).

I’m glad I went down the route of getting a cheap computer and a top end monitor, instead of the other way around. I’ve had total confidence that what I’m seeing on the FSI monitor is accurate and I’ve been able to get around the shortcomings of the computer by using the render cache options in Resolve.

However, I have found the lack of real-time processing when grading was painful and I’ve often rendered clips out only to see something I’ve done wrong which I didn’t notice when grading on a still frame but which stands out when the clip is moving. Also, I could never get playback to work unless I set the SDI output to 8bit not 10bit. The main thing I needed was a better graphics card (GPU). My iMac has as a 2GB GPU which really isn’t enough. So I’ve been keeping my eye on how best to upgrade to a bigger GPU. The biggest card available for the iMac is 4GB (I was hoping for 6GB) and it turns out that I couldn’t upgrade my particular iMac anyway.

So, should I buy a new iMac just to get a 4GB GPU? The top of the range iMac is $3399 for a quad core i7 processor and a 4GB GPU. The ’new’ MacPro cost a lot more than that and it’s has been plagued with corrupted renders due to overheating so I didn’t want to go that way. A new PC on the other hand would be more upgradable and cost a lot less.

Under $2k

I found that the Cyberpowerpc website was brilliant for the price range I was looking at, letting you configure a custom ‘gaming’ or ‘VR Ready’ PC and see what you can get for your budget. I looked at other similar sites but they were either worse value or a higher range of workstations which were more than I wanted to spend. Also, Cyberpower are continually doing offers, for Black Friday, New Year, etc.

In the end I waited until the Christmas/New Year sales and got myself a free 240GB SSD, a $50 cash card and a 5% discount by selecting the ‘no rush’ option.

My new machine is now up and running. It’s a six core i7 6800K, a 8GB GeForce GTX 1080 GPU, 32GB RAM, 250 GB SSD system drive, plus a 240 GB SSD and a pair of 2TB hard drives RAID 1 for a little extra speed (no extra speed as it turns out) and backup. All for $1914 (as a comparison, I just saw a new 6 core new Mac Pro (2x6GB GPU) for $5200).

I also got a cheap QNIX 25610x1440 glossy monitor from (NewEgg Business) which I’m very pleased with for the money. I wanted to have that resolution because the UI in Resolve looks quite different when you go lower. I wasn’t worried about the colour accuracy of the UI because I’m grading looking at the FSI.

Thunderbolt 3 over USB-C

I chose a particular motherboard because it claimed to have Thunderbolt 3 on board. The only problem was that Cyberpower installed my Gigabyte X99P-SLI motherboard without updating the BIOS to a version which supported Thunderbolt 3. Cyberpower actually said I could ship the whole system back to them at no cost and they’d sort it out for me. After some investigation and help from the BlackMagic Resolve forum, I managed to install new drivers, then update the BIOS (a bit scary for me but easy enough in the end) and then update the Thunderbolt Firmware. So now I can use my old Thunderbolt BMD UltraStudio Mini Monitor - via a $29 Thunderbolt 3 (USB-C) to Thunderbolt 2 (Mini Display Port) adapter. I later discovered that when I did the BIOS update I’d undone the RAID 1 configuration of my HDD so I had to reconfigure that in the BIOS (this didn't fill me with the confidence I was looking for with RAID1!). Anyway, I got Thunderbolt 3 to work and I can monitor 10bit SDI.

No QuickTime

I’ve been trying to avoid putting even the basic player-only components of QuickTime on my new PC. I’ve been rendering DNxHD OP1a .mxf instead of using ProRes which works well. I’ve tested it by bringing it into Premiere Pro on the iMac and comparing it to renders done with ProRes and they look identical. I’ve installed VLC player which is OK for opening up a .mxf but the levels look way off. I’ve just installed Telestream Switch Player (free) and it seems to work well, uses JKL keys and looked better although I keep tweaking my UI so I’m still not sure if it looks much different to VLC in terms of colours and levels.

Resolve and Premiere Pro seems to handle playing Quicktime even though I haven’t installed the QuickTime player on the PC but I ran into a problem when I tried using Fusion, it doesn’t seem to read ProRes and Fusion Connect doesn’t offer a DNxHD OP1a option so I need to look at better ways to use Fusion Connect. I ended selecting DPX so it has to render out the source footage from Resolve and renders back out of Fusion as .dpx and I think this is going to use up my limited drive space too quickly. Playback of .dpx was pushing the data rate from my drives - I had Cyberpower RAID 1 a pair of 2TB drives and I’m getting about 190Mb/s playback but that still isn’t enough for the Fusion .dpx renders. I’ve now moved and recreated the Fusion Connect clips so that they’re all on the free SSD I got and that’s working fine. Now they’re on an-unbacked-up SSD so I’ll have to make some back ups of the Fusion comps somehow.

Using it

My old iMac used to drop out of realtime and skip frames after about three blur nodes of in Resolve (on ProRes HD). I got bored trying to make the new PC drop out or realtime after 32 blur nodes, it just keeps playing! The system handles mp4 pretty well but isn’t a lot faster than my old one when it comes to decoding Red. I can get realtime playback on Red 4K (copied to the SSD) if I use the Half Res Good setting, higher than that and I can see the CPU usage max out and it drops frames. So with that setting it looks like I can do what I like with the grade because the GTX 1080 handles it once’s it’s decoded by the CPU. I’m happy with that.

This has made me wonder about the choices I made… I wonder if I should have gone for the slightly cheaper GTX 1070 and got a more expensive i7 6850K. I think the difference either way would be minimal. Going to an 8 core, faster clocked i7 might make an occasional difference but that would have gone over my budget so I can still say I’m more than happy with what I bought for the money.

I keep tweaking the new UI monitor with the nVidia tools to get it to match the SDI-out a bit better. Not a big problem though. I don’t like that fact that whichever player I use (VLC, Switch) the levels look wrong compared to what I see in the Resolve viewer (which I’ve used to roughly set a match to the broadcast FSI monitor).

So I now have a new system which is almost as powerful as the best Mac available and I can upgrade or add any components as I need to. I could add new hard drives, add a second GPU, I could even upgrade the processor to a 10 core i7. But I don't think I will just now!

The best thing is that I can send .mxf files to my current client it makes no difference to them.

Let me know if you found this useful - @dickij10