Real-time Playback Issue – ProRes 444 1080i 59.94

[Craig Harris]

According to the Black-Magic speed test, you’d need a drive transfer speed of about 580 MB/s

[Uli Plank]

ProRes 4444 has only 330 mbps, that’s a bit over 40 MB/Sec…

Director of the Institute of Media Research (IMF) at Braunschweig University of Arts

[Chris Hall]

Well just double checked the Final Cut Pro Studio ProRes Whitepaper and Prores 444 data rate is indeed 330Mb/s:

https://images.apple.com/finalcutstudio/docs/Apple_ProRes_White_Paper_July_2009.pdf

I benchmarked my RAID5 array again, and found out that I’m actually only getting 300Mb/s, which is of course my problem. I’ve consistenly gotten 500Mb/s out of this RAID and all of a sudden I’ve dropped to almost half! Not sure why. I’ve cleared out half of the storage and it is still running at 300Mb/s max (RocketRaid 4322 Card, to tower with 8 Sata 1TB drives). I’ve got a call into to Highpoint to try and troubleshoot this… no idea why its slower now. Anyone have experience with RAID5’s slowing down on them (possibly after a lot of writing and rewriting to the drives?).

Chris Hall
Colorist – Basher Films
Pasadena, CA

[Craig Harris]

Is the MB/s second the same for 23.98 and 59.94?

[Gary Taylor]

Hi Chris,

I think you might be confusing Mb (megabits) with MB (megabytes). Your array should be more than capable of handling multiple streams of ProRes 4:4:4.

Gary

[Craig Harris]

Depending on the drives and RAID controller, a RAID 5 array can have an increased loss of performance as you fill the drives with content. Do you still have lots of space on your array or are you close to capacity?

Also, are you running Mini-Sas or Fibre?

[Uli Plank]

Yes, I think you are confusing units here. MB (capital B) is groups of eight bits, as in mb (lower case).

So, 330 mbps is a bit more than 40 MBps, which even a single SATa drive can deliver today. Any RAID should deliver more than that, and I suppose yours is doing 300 MB per second.

The problem must be somewhere else.

Director of the Institute of Media Research (IMF) at Braunschweig University of Arts

[Dwaine Maggart]

This looks like an area where having more/faster CPU’s on the Mac could help you.

Do you have any WFM displays turned on? If so, turn those off, and you’ll find it plays at 30.

If you can’t live without the WFM(s), you can also try turning on the Real Time Proxy mode on the config tab. On my dual quad core 2.26Ghz 2009 Mac, that works, and I can add some nodes of correction and maintain 30 FPS playback speed with a WFM turned on. But you’ll be able to do more nodes without the WFM, and then you can also turn off the proxy mode.

Dwaine Maggart
Blackmagic Design DaVinci Support

[Craig Harris]

Uli,
A drive that has 330 MB/s could be problematic, depending on the codec. ProRes 4444 should be fine though as it requires approx. 45 MB/s of throughput. At 330 MB/s, you should be able to get 3 to 4 streams of PR4444.

Here are a couple of performance benchmarks you would get with a drive & 330 MB/s throughput if using uncompressed codecs:

-12 Bit RGB 4:4:4 / 1920×1080 (Only 38 frames per second)
-10 Bit RGB 4:4:4 / 1920×1080 (42 frames per second)
-10 Bit YUV 4:2:2 / 1920×1080 (64 frames per second)

[Chris Hall]

Hey sorry for the bits and bytes confusion. It is in fact megabits per second which is mbps. Blackmagic’s own disk speed utility has it labeled wrong (they label it as MB/s which I’m assuming should be mb/s, see the pic below (someone correct me if I’m wrong again):

Prores is rated at 330mb/s and my array is only giving me 300mb/s at the moment which is obviously not fast enought; I usually get 500mb/s out of this guy, so I think my issue is with my RAID hardware. I’m restriping my array tonight and I’m going to test it in the morning, thinking I might have a PCI-E I/O conflict possibly as well that’s bottlenecking things.

On another note, Dwaine, thanks for the advice on the waveforms, once I get the RAID issue sorted out I’m going to use that if I get playback issues for sure. Another question for you, are “on the fly” proxies actually DPX files, and if so how do they differ from the “render cache” option.

Chris Hall
Colorist – Basher Films
Pasadena, CA