Looks like 35.4MB per frame. Multiplying by 23.976 Fps equals approx 849 MB/sec. Looking up USB 3 speed:USB 3.0, which can handle up to 5gbps (640MBps). So even a big USB 3 raid tower wouldn't provide the necessary bandwidth from what I can tell.
It seems only 10gig ethernet would handle the load. 10 gig would be 1.2GB/sec or 1200MB/sec so that would cover 849MB/sec requirement. I also see that a 10 gig card like the sonnet presto requires 8 to 16 lane slot, Right now I have a cyclone micros systems expansion chassis connected from the 16 lane slot in the MacPro Tower. There are three 16 lane slots in the chassis. The first two are used by the two Titan X cards.
So if the path from the mac pro tower to expansion chassis is 16 lanes and the 10 gig card requires 8 lanes does that mean that only 8 lanes would be available for the GPU data. I don't have a feel for how lanes related to actual bandwidth. Does it make sense that DPX frames being so large would require less computation like how uncompressed is easier on the CPU but harder on bandwidth requirements.
I just wonder if that would really do it. Here's the info from Sonnet:
The Presto 10GbE 1-Port 10 Gigabit Ethernet PCI Express adapter card enables you to connect your computer to high-speed infrastructure and storage without stepping down in speed. Setup is simple—install the low-profile card into an available x8 or x16 PCIe slot in your computer, install a driver, connect to the switch or 10GbE port via LC fiber optic or copper cable (sold separately), and then configure the card through the OS X® Network control panel or Windows® Device Manager.
Such a high bandwidth requirement makes me wonder how many people are actually playing DPX in real time.
---In Avid-L2@yahoogroups.com, <bogdan_grigorescu@...> wrote :
looks to me you don't have the necessary disk throughput - nothing to do with GPU/CPU performance
DPX 10 bit UHD is around 32MB/frame or ~800MB/sec - true 4K probably close to 40MB/frame
You'll need at least 800MB/sec sustained from your drives in order to play back in realtime - nevermind the overhead of file sequence, nevermind the inaccuracy of BMD disk speed test, which is mostly good for contiguous files.
BG
www.finale.tv
On Friday, May 10, 2019, 7:27:30 p.m. PDT, bigfish@... [Avid-L2] <Avid-L2@yahoogroups.com> wrote:
I exported to 10 bit RGB 4096_2160 from Avid. So I guess that's DCI or sometimes called true 4K. I've played around with setting timeline the HD etc... but nothing seems to get playback without stutter.
I haven't ever performance tested the system but I do know that with and OWC Elite 2 drive Raid with the camera original which is from a Panasonic Varicam 35 shooting AVC-Intra YUV 10bit Vlog I could playback the timeline with out any color correction but just a source LUT vlog to rec 709 without stutters.
I would think that would be more computationally intensive than a DPX but I've only exported DPX from Avid and never been able to play it back in Avid world other than to spot check.
Am I wrong to think my 2 TitanX expansion chassis should be able to do this? The audio doesn't stutter so the timeline is rolling along at 23.976 just both the GUI and the DNxIO show stutters. I can't tell if the stutters I see in the GUI are identical to those on the DNxIO output because it's too choppy. In color page the audio also stutters which is different because usually I've seen better performance in color page than the edit page. Perhaps that has changed in updated versions. Also the choppy playback occasionally goes maybe a second in sync so the timeline is rolling without a hiccup it's just the displays that are not updating.
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Posted by: bigfish@pacbell.net
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