Dropped frames - but only after a while

Morning all, first post here

I am not a pro photographer but literally saved (for nearly two years!) to get a BMP4K as I wanted to do some hobbyist shooting for some projects as a bit of a bucketlist thing. So I finally have my camera (hurrah) and it's brilliant, I've also adapted it to take an external USB C SSD with a mount I 3d printed, and all seems ok.

Last two times I've been out filming I have noticed a problem though with dropped frames. This only became apparent after an hour or so of trouble free filming. I initially put this down to using my own choice of SSD (happened to be a really good sale on when i bought the storage) so I forgot about it, but I ultimately thought I'd ask here because one thing that bugs me about it is the problem doesn't have the characteristics of a too slow or unapproved storage device - I would expect a speed issue to be a constant problem, where it seems at the moment my camera actually gets progressively worse with time.

This indicates it might be heat related etc, but the camera is not in 'that intensive' use - think recording for 15 minutes, 5 minutes relocation and another 15 minutes. I don't beleive the camera is getting hot but the SSD could be?

Just wondering if people have any thoughts or other possible explanations, nothing 'feels' hot.

TIA

I have tested this card, and could NOT get a failure no matter what I tried.

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

Just wondering if people have any thoughts or other possible explanations, nothing 'feels' hot.

Step one is that you've gotta tell us what SSD you're using. Not all SSDs are created equal!

Here's a link to BMD's list of approved media for the BMPCC4K. If your SSD isn't on that list, there's probably a reason. One thing to note: Samsung really messed up by giving the T7, T7 Touch, and T7 Shield all very similar names because they are not the same drive on the inside. The T7 Shield is the only one of those three that can actually keep up with BMD's cameras, so avoid the T7 and T7 Touch.

Let me guess, you are using a Samsung T5, T7, or T7 Shield... All drives with a low sustained write speed.

All those drives exhibit a drop in write speed that causes dropped frames. Some people get good batches, but them eventually their drives or their cables crap out...

Let me guess, you are using a Samsung T5, T7, or T7 Shield... All drives with a low sustained write speed.

...I'm not really sure why you keep saying this when it is demonstrably untrue. The only unusable drive in the three you mentioned is the vanilla T7.

At this point, considering how often this question is asked on this forum, BM should really supply their list of approved media on a card or other literature in the box with their cameras.

Or just a piece of paper with bold words: "the non-Shield Samsung T7 is not approved for this camera".

Let me guess, you are using a Samsung T5, T7, or T7 Shield... All drives with a low sustained write speed.

...I'm not really sure why you keep saying this when it is demonstrably untrue. The only unusable drive in the three you mentioned is the vanilla T7.

I don't know why you keep denying it. Read the posts here about dropped frames with all three. Read the Facebook Blackmagic groups echoing the same thing.

You want to tell them their drives should work on paper?

https://www.facebook.com/groups/2327676 ... 067471369/

https://www.facebook.com/groups/2327676 ... 370417202/

https://www.facebook.com/groups/2327676 ... 016331435/

https://www.facebook.com/groups/2327676 ... 455656226/


Shall I continue?

I don't know why you keep denying it. Read the posts here about dropped frames with all three. Read the Facebook Blackmagic groups echoing the same thing.

You want to tell them their drives should work on paper?

Pretty much, yeah. Seems like user error in all but one of these:

https://www.facebook.com/groups/232767647318084/permalink/864568067471369/

6K 50FPS @ Q0 is more data than a USB3 port can actually handle, period. No drive could do what they're asking because the camera is the bottleneck. Despite being advertised as a 5Gbps (625BM/s) standard, USB3 can't realistically handle more than around 425MB/s and 6K 50FPS @ Q0 can go well beyond that.

https://www.facebook.com/groups/232767647318084/permalink/1201776370417202/

If you actually bothered to read the comments on this one, they fixed the issue by restoring factory defaults and updating the firmware. FW 7.9.1 made some changes to the way the camera interacted with USB drives, and it looked like 7.9.2 fixed everything up for this user.

https://www.facebook.com/groups/232767647318084/permalink/1442634016331435/

They don't really give much info here, but the telltale sign here is that they're only able to roll ProRes LT UHD at 24FPS. That's around the bandwidth where USB2 tops out, so I'm going to hazard a guess that some of the extended data pins on either the SSD or the camera are damaged, causing the combination to negotiate lower than normal speeds. They only say they tried one SSD, so who knows if the SSD or the camera is the problem.

https://www.facebook.com/groups/232767647318084/permalink/1282719455656226/

So they recently changed their cable and they're having issues? Hmm... I wonder what the problem could be?

Shall I continue?

Look, I get the impression that you have had problems with Samsung drives in the past and had a very frustrating time troubleshooting that, which I sympathize with. But BMD has certified a bunch of their drives; I own a bunch and have used them without issue; and pretty much all the problems I see people having with them boil down to user error. I'm really not sure what to tell you other than the majority of people having problems with T5 and T7Shield drives are having those issues because they're not using them properly. ¯\_(ツ)_/¯

They can't really certify someone elses product without a partnership.
If samsung decides to change the spec / hardware revision on the same P/N, BMD wouldn't know that or be able to control it.

That's why BMD needs to release their own line of storage, even if that's just buying samsung drives and relabeling them; it would allow BMD to test/control the manufacturing changes before it reaches the end user.
They could slap a 20-50% premium on top and i'm sure people would still be happy.

The constant discussions about usable media is proof that this is needed.

All cables are not created equal.