How would you record 6K 50p BRAW Q0 at all?

Hi.

I'm new to the forums, but I have browsed around for a while and I have also had the pleasure of playing with the BMPCC4K for a little while.

As with any Pocket user, you end up looking into storage options. I always shot on the CFAST card because that was what came with the Camera. I have access to the camera through a co-op set up so it's not mine.

After I bought the Samsung T7 (before reading about how it doesn't work with the BMPCC), I naturally went down a rabbit hole and learned all there is to learn about the storage options. Well, almost. That's what this thread is all about. I was curious about how you would deal with the absolute maximum load you could punish these cameras with.

First, let's have a look at the requirements for the footage listed on BM's site:

The highest load a 4K 30p shot will transfer to your storage on the BMPCC4K is the Blackmagic RAW Constant Quality Q0.

- 4K Blackmagic RAW Constant Quality Q0: 102MB/s to 203MB/s
- 6K Blackmagic RAW Constant Quality Q0: 242MB/s to 483MB/s

This is 30p, so with some naive math, we could try to convert this to 50p, which is the maximum of what the 6K Pro can do in 6K, we end up with a factor of 0.66 (66%). 30 + 30x0.66 = 50ish. If we then transfer this to the write speed we end up with 402MB/s to 802MB/s for the 6K PRO. Please correct me if I can not think like this and the numbers are far off. I don't have the 6K PRO to test with so I have to do it theoretically here.

If we look at the write speed of SD cards and CFAST cards used with the BMPCC, we have this:
- An Angelbird AV PRO SD MKII V90 gives you a write speed of 280MB/s.
- An Angelbird AV PRO CFAST 2.0 gives you a write speed of 400MB/s
- A Samsung T5 SSD gives you an advertised transfer speed of 540MB/s (Requires USB 3.2 Gen 1 Host/Cables & UASP activated)

This means that none of these are able to record the most advanced Q0 shot in 6K 50p.
The Samsung T7 lists a write speed of 1000MB/s, but it is using some sort of buffer wizardry or something so that can't store anything from the BMPCC. This way the write speed of 1000 is worthless.

From the list of BM's approved SSD drives, we have a write speed of around 540MB/s

Some drives, like the Delkin Juggler, and G-Drive Mobile SSD, both list write speed of 1000MB/s and is approved by BM. The question is if they actually deliver this. If so, is the solution to simply use one of these?

Then another question arise. The USB-C 3.1 Speed is 5Gb/s which translates to 625MB/s. Is the port limiting the possibility to record that 802MB/s shot?

If so, and you decide to go for the Ninja V, what is the max output of the HDMI on the BMPCC 6K PRO? I can't find what speed the port is, but let's say it's 18Gb/s. That gives us a transfer speed of 2250MB/s. Finally

Drives for the Ninja V are SSD SATA drives if I understood correctly, and an Angelbird Drive tailored for the Ninja V has a write speed of 500MB/s. That brings us back to square one. Can you use faster drives with the Ninja V? Like nvme M.2? These drives are blazing fast as far as I know and speed-theoreticallly wise a valid option.

So to sum up the longest thread in the world, how would you record 50p 6K BRAW Q0?

Feel free to correct any numbers I presented here. I might be in the wrong here.

thanks,
M

6k 2.41 50p q0 and 3:1 is possible on fast support
I had San disk extreme ssd on startech box with ausp and allow me to do that at 400 1250 3200 8000 25600 iso.
I tested ssd not nvme be cause I had Ursa Mini Pro g1, pocket 4K and 6k and 625 is also the limit of usb 3.1.

Yesterday I tested San disk extreme ssd // samsung evo 860
in startech box usb with ausp https://amzn.to/35w85rR

i tested with 400 3200 iso.

6k 50p
Q3 full disk without stop
5:1 full disk without stop

6k 2.4.1 50p
Q0 full disk without stop
3:1 full disk without stop

6k 30p
3:1 full disk without stop
Q0 full disk without stop

5.7k 60p
5:1 full disk without stop



Inviato dal mio iPhone utilizzando Tapatalk

Angelbird CFast2.0 cards do write at around 450-500 MB/s.

You can use my calc sheet to calculate the data rates for BMD cameras:
viewtopic.php?f=2&t=118151

6k 2.41 50p q0 and 3:1 is possible on fast support
I had San disk extreme ssd on startech box with ausp and allow me to do that at 400 1250 3200 8000 25600 iso.
I tested ssd not nvme be cause I had Ursa Mini Pro g1, pocket 4K and 6k and 625 is also the limit of usb 3.1.

Yesterday I tested San disk extreme ssd // samsung evo 860
in startech box usb with ausp https://amzn.to/35w85rR

i tested with 400 3200 iso.

6k 50p
Q3 full disk without stop
5:1 full disk without stop

6k 2.4.1 50p
Q0 full disk without stop
3:1 full disk without stop

6k 30p
3:1 full disk without stop
Q0 full disk without stop

5.7k 60p
5:1 full disk without stop



Inviato dal mio iPhone utilizzando Tapatalk

Hi, Which Sandisk Extreme you tried? There is different types as E60/61 and E80/81. I think to buy the E61 which provide 1000MB/s, don't see any reason to go higher because the bottleneck of GEN1 USB hub. Just another question, this results with internal battery?

6k 2.41 50p q0 and 3:1 is possible on fast support
I had San disk extreme ssd on startech box with ausp and allow me to do that at 400 1250 3200 8000 25600 iso.
I tested ssd not nvme be cause I had Ursa Mini Pro g1, pocket 4K and 6k and 625 is also the limit of usb 3.1.

Yesterday I tested San disk extreme ssd // samsung evo 860
in startech box usb with ausp https://amzn.to/35w85rR

i tested with 400 3200 iso.

6k 50p
Q3 full disk without stop
5:1 full disk without stop

6k 2.4.1 50p
Q0 full disk without stop
3:1 full disk without stop

6k 30p
3:1 full disk without stop
Q0 full disk without stop

5.7k 60p
5:1 full disk without stop



Inviato dal mio iPhone utilizzando Tapatalk

Hi, Which Sandisk Extreme you tried? There is different types as E60/61 and E80/81. I think to buy the E61 which provide 1000MB/s, don't see any reason to go higher because the bottleneck of GEN1 USB hub. Just another question, this results with internal battery?

i not able to tell you what type immediately, this ssd are that i bought in 2015 to use with production camera 4k.
i do ever with external battery, internal battery give too often big performance problem to external disk.
I back to home, where I can see that indication of ssd type?
Are sure that ssd give 1000mb/s ? How can reach that speed if sata standard is limited to 625 mb/s?

A good question I have an Nvme m.2 drive in the smallrig enclosure and it was working, then stopped recording full 6k at Q0 50p or 30p at all.

This is a good Kingston PCI NVME (Not sata as that is too slow) and the drive is well capable of recording what is essentially slowish data rates (compared to PC usage), I can edit the raw files from this drive easily and playback at full speed in resolve.

So there is something weird going on with the bmpcc6k itself, the older USB standard is not great so I do wonder why they put it on this design, but again, it was recording in these formats at Q0 & Q3. Now it is a struggle to get Q5 to work on the full 6k res, sometimes it works, sometimes it doesn't.

I believe this to be tied to a camera update that occurred.

As I shoot anamorphic, I want to use as many pixels as possible to keep image clarity once the desqueeze occurs (I'm not going to use the in-built anamorphic modes as they are a little restrictive and I want to reframe/stabilise etc).

But the issue gets complicated, because if there is a high degree of light variation then it will require using more data, which will increase the likelihood the bottleneck of the USB connection is overrun resulting in dropped frames.

I am going to test using the cable I use for my computer (it's USB 4) rather than the one smallrig shipped with their case and see if that makes a difference.

I refuse to use CFAST/SDCards due to the quality of components in use (they are all pretty rubbish).

Hey @BlackMagic, any recommendations of setup to get this working consistently.

BRAW recordings at a Constant Quanity such as 5:1 are predictable in their execution at a constant bitrate. Constant Quality such as Q0 are variable bitrate so there is a range of values possible with estimated minimum and maximum bitrates. But those are only estimates. My suspicion is that the camera may be able to give you the lowest bitrate possible for maximum published frame rates quoted. Just conjecture on my part.

First off to OP 6K wont be recorded on a pocket 4K. Then to Rick, 5:1 is Constant Rate.

One of the important considerations and tactics to getting 6K 50p BRAW Q0 is the Constant Quality (not Constant Bit Rate) and how much information is trying to be recorded in each frame. A frame with sharp detail everywhere across it will generate much more data per frame then a frame with low detail or out-of-focus/ blurred/ dark information. Keeping this in consideration when shooting or planning the shoot can allow one to go beyond the published data rates.

Plan ahead and test shoot some of the scenes to determine the Q setting (Constant Quality) that works.

Also, another consideration is how long the shot will be. Short clips of several seconds can work at higher data collection settings than long (more than a minute) shots. Many successful films or sequences are made with only very short clips. Constant Quality can be your friend.

First off to OP 6K wont be recorded on a pocket 4K. Then to Rick, 5:1 is Constant Rate.

The OP's question and Rick's answer are clearly about data rate, not how to shoot.

This is a good Kingston PCI NVME (Not sata as that is too slow)

So there is something weird going on with the bmpcc6k itself.

Sata is enough to saturate the bandwitch of usb 3.1 of pocket6k.
Test that I could did to record with my pocket6k was done with sata ssd, which was enough to record 60p cong I compressed from ursa mini pro at 4.6k.
You can see my results some post upper this one

Nvme are better and faster but… suffer of thermal throttling, suffer if you not give enough power and reduce speed.

Pocket4k and 6k g1 (I not checked others) are simple usb 3.1 625mb/s speed, if you have a better disk is useful only when you offload data’s.

Enclosure is not less important keypoint, if controller of enclosure is not enough good, it was the bottleneck.

The best is ever buy suggested support from approved list, and from what I remember no one is approved to record at best speed and best quality Q0.


Inviato dal mio iPhone utilizzando Tapatalk

Although, it’s not a general solution, Jeffrey does make some good points on the technique to get some Q0 shots successfully: blurred and brief may help when appropriate to the shot list. At least worth a test for Pocket 6K shooters.

Just want to report that I had no dropped frames shooting 6K BRAW Q0 on the Ursa Broadcast G2 on the following card.

https://www.bhphotovideo.com/c/product/ ... _525r.html

In fact, between the Ursa and P4k, I have not been able to get this card to fail with ANY codec, resolution or frame rate combination. The damn thing is bullet-proof!

Good to know, Jim. It appears their largest card 512 GB is on sale currently for $399:

https://www.bhphotovideo.com/c/product/1317915-REG

According to https://www.braw.info/capacity/, a 6K 50fps video at Q0 takes ~376.64 MBps, which is below the maximum speed of the SATA 2.0 spec of the CFast 2.0 specification (SATA 3.0; ~600 MB/second). Make sure you are using a true CFast 2.0 card, as many cards are not fully specification compliant.

I use a Zitay CFast to SSD adapter from Amazon, and a Teamgroup T-Create 2.5" SSD, though you can get a M.2 SSD Form Factor adapter. Either way, you must use an M.2 (NOT NVME) SSD that conforms to the SATA protocol. These are much less expensive than CFast cards, and I suspect will be longer lived because of the better heat dissipation.

I use a ORICO enclosure with a Crucial MX500 to hit 6K 50p Braw Q0.