In our previous article, we discussed the need for a travel PC to handle the demands of life on the road. One of the key points we considered for this build was part of the DIT duties that this PC will handle and how to maximise our data transfer speeds.
We have previously filmed heavily in 4K RAW so we know a thing our two about data management, however, the jump to a RED Epic-W 8K was generating data like we’ve never seen. RED have a handy calculator to help you manage your data storage times on set.
Over at www.red.com/tools/recording-time, you can select the parameters for filming to give you time estimates. You select the RED Camera you are shooting on, the resolution you are filming at, your frame rate, REDCODE, finally the size of the mag you are using.
For us, we are using the high-speed 512GB Mini Mags and shooting at a moderate compression of 10:1 to give us a balance between data retention in recording and having a high-quality image capture, yet extending our recording time.
As you can see from the calculator, our maximum record time for a 512GB card is 65 minutes. Now for anyone that has done a full day shoot, you know that you’ll hit 65 minutes of recording before you know it. This is where we have had lengthy discussions around getting our data transfer speeds to their upper limits.
We have found that most of our other media like CF cards are moving at a maximum of around 90 MBPS which if you multiply that out over these kinds of data sizes, you are talking about some serious chunks of time for data offload.
When you think that 512,000MB x 90MB/s you’re looking at just over 90 minutes of data transfer for 65 minutes of filming. Those numbers aren’t great when the pressure’s on!
Fortunately, the RED Mini-Mag reader can consistently maintain a speed of over 300MB/s and when you look at the number, you start to truly understand why speed matters. Based on a speed of 300MB/s you are now at 27 minutes for the same data offload.
There are limiting factors seen at every link in the chain, and trying to maximise the speed at each link Is the whole game. We know that both the Mag and the Mag Reader are going to be cranking at their maximum possible output. Where you can make speed gains is in the throughput and the write speed.
This is why we have SSD’s onboard so for maximum speed at offload, we write directly to these. One of the key speed failure points is the write speed. If you can’t lay that data down any faster, then the speed will always be limited. The opportunity here is that the new RED Mini-Mag reader utilising USB 3.1 will give increased speeds, so we have one on order after seeing them in the RED Store in NYC! With an April shipping date, we should have one soon!
We may also upgrade our onboard data storage to m.2 drives to give us an additional speed advantage.
The most exciting part of this exercise was when we finished the PC and tried our first data offload and hit peak speeds of 420MB/s and maintained a constant speed just over 400MB/s. Again, when you do the math, the 512GB card at 400MB/s equals an offload time of 20 minutes. When you are on set and you have limited turn around times, these numbers matter.
We spent a lot of time doing the math on the theoretical limits, then running the real world scenarios to get the most out of the technology we are using. There is always more speed to be found and we’re excited to keep finding ways to enhance our efficiency in production.