- Posts: 16
- Joined: Sat Nov 10, 2012 3:26 am
- Real Name: Jean-David Collard
Hi
As many others here I'm waiting my BMPCC 4K to ship.
I have asked BM support about certified media to handle 4K DCI @60fps RAW, but they could not give me any information, and they have not yet published certified media list for this camera.
I need that for a specific project where each frames is treated as a still, and need the best possible quality.
I would like then to discuss which media can support 4K DCI @60fps dng.
Official BMPCC 4K specs on BM website says 272 MB/s @30fps.
That means 544 MB/s @60fps.
As stated here by Kristian Lam:
viewtopic.php?f=2&t=72674&p=413154&hilit=bottleneck#p413154
BMPCC USB-C port "It will be USB 3.1 Gen 1 (5 Gbps)."
If it is 5 Gbps, it's in reality is USB 3.0 Gen 1, not 3.1 Gen 1 ?
Now concerning USB 3 gen 1:
https://en.wikipedia.org/wiki/USB#USB_3.x
"At a 5 Gbit/s (625 Mbyte/s) signaling rate with 8b/10b encoding, the raw throughput is 500 Mbyte/s. When flow control, packet framing and protocol overhead are considered, it is realistic for 400 Mbyte/s (3.2 Gbit/s) or more to be delivered to an application"
So clearly, my doubt is: how can BMPCC 4K record 544 MB/s on a SSD if USB port bottleneck at 400 MB/s?
I've been hoping to use a M.2 MVMe fast SSD in an MVMe USB-C enclosure, but my hope have vanished.
I would be glad to have this community other members opinion.
Thanks
Jean-David
As many others here I'm waiting my BMPCC 4K to ship.
I have asked BM support about certified media to handle 4K DCI @60fps RAW, but they could not give me any information, and they have not yet published certified media list for this camera.
I need that for a specific project where each frames is treated as a still, and need the best possible quality.
I would like then to discuss which media can support 4K DCI @60fps dng.
Official BMPCC 4K specs on BM website says 272 MB/s @30fps.
That means 544 MB/s @60fps.
As stated here by Kristian Lam:
viewtopic.php?f=2&t=72674&p=413154&hilit=bottleneck#p413154
BMPCC USB-C port "It will be USB 3.1 Gen 1 (5 Gbps)."
If it is 5 Gbps, it's in reality is USB 3.0 Gen 1, not 3.1 Gen 1 ?
Now concerning USB 3 gen 1:
https://en.wikipedia.org/wiki/USB#USB_3.x
"At a 5 Gbit/s (625 Mbyte/s) signaling rate with 8b/10b encoding, the raw throughput is 500 Mbyte/s. When flow control, packet framing and protocol overhead are considered, it is realistic for 400 Mbyte/s (3.2 Gbit/s) or more to be delivered to an application"
So clearly, my doubt is: how can BMPCC 4K record 544 MB/s on a SSD if USB port bottleneck at 400 MB/s?
I've been hoping to use a M.2 MVMe fast SSD in an MVMe USB-C enclosure, but my hope have vanished.
I would be glad to have this community other members opinion.
Thanks
Jean-David
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Jean-David Collard
Jean-David Collard