Ursa Mini Pro 4.6 G1 DROPPING FRAMES

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Stephanie

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Ursa Mini Pro 4.6 G1 DROPPING FRAMES

PostTue Oct 08, 2019 6:36 am

I am having an issue with my Blackmagic Ursa Mini Pro 4.6k EF mount. I have a c-fast to SSD adaptor on the back.

I have recently experienced a number of times the camera dropping frames and therefore stopping recording mid-take. An exclamation mark comes up on the screen. I know I can toggle the setting in the menu that will allow camera to keep recording while dropping frames, but I want to know what the issue is with the camera.

I am on firmware version 6.2 and on Blackmagic Camera Setup it says I am up to date.

I have noticed it mainly while shooting BRAW 5:1 but it has also happened while shooting prores 422 (even at 2k). It has mainly been when shooting 50fps as well.

I have also noticed the battery level flickers to red sometimes randomly and I cannot trust the battery level shown on screen.

I would like to know if anyone else has a similar problem and if so, would it most likely be a problem with the firmware, with the camera or with my cfast to SSD adaptor?
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Donnell Henry

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Re: Ursa Mini Pro 4.6 G1 DROPPING FRAMES

PostTue Oct 08, 2019 4:33 pm

The most likely culprits are either your Cfast to ssd adapter or your SSD itself. Did you check to see if your SSD is on blackmagic’s approved list? That’s the first thing I would check by process of elimination. Most times that is the issue. I have a G1 as well with the blackmagic SSD module attached. I don’t get dropped frames as long as I stick within the guidelines for my particular SSD and the shooting format. BRAW 5:1 at 50fps per sec may not be doable on your particular SSD. As for the battery levels flickering, that meter gives you a rough percentage/bar average on your battery time. It’s not precise. What it does well is letting you know your battery is low before it just completely shut off on you in the middle of your shoot. Sometimes mine flicker as well. It’s normal. When that happens I know I have an average of 10 minutes or less before I change my battery

CHECK HERE FOR SSD COMPATIBLY: https://www.blackmagicdesign.com/support/faq/59015
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Robert Niessner

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Re: Ursa Mini Pro 4.6 G1 DROPPING FRAMES

PostTue Oct 08, 2019 4:53 pm

Stephanie, how exactly are you powering your camera?
And on which SSD exactly are you trying to record to?

BRAW 5:1 @ 50 fps needs ~185 MByte/s - so while this isn't especially demanding, it might be too much bandwidth for a cheaper SSD. You have to be aware of the fact, that most SSDs are using a certain part of its cells as a write cache (maybe like 32 GB or so) which is very fast, but when this cache area has been filled up, write speeds can drop very low - even slower than a spinning hard drive.
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robert Hart

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Re: Ursa Mini Pro 4.6 G1 DROPPING FRAMES

PostTue Oct 08, 2019 4:54 pm

Is the SSD recorder one of those aftermarket products which uses cFast inserts and bridge cables to the SSD recorder?

If it is, then the cables themselves may be a culprit. I have never known a SATA style cable and plug that was ever any good yet.

The computer SATA cables all have a fatal flaw in the plug design as the cables are too stiff and the plugs cannot handle the bending or tension forces the cables impose in an agile situation.

I have not studied the aftermarket asian SSD adaptors closely but the data cables appear to be the same stiff SATA style cable material.

You may be experiencing unwanted movement of the cFast adapters within the camera body and intermittant contact causing your dropouts.

If the SSD recorder is itself interposed between the battery mount and the camera body, then there could be an intermittant fault momentarily breaking power to the camera and the SSD drive. Some Sony V-mount style backs do not anchor the batteries tightly and they move on the contacts causing problems.

My personal preference to deal with both issues would be as best you can. - Immobilise the cables by taping them to the camera body so that movements and mechanical stresses are not passed to the cFast inserts. Immobilise the battery by wrap-taping it firmly to its mount.

It is a big ask but try not to bump the cables or the battery when operating agile.

If the battery is repeatedly losing contact with the camera it may become a case of not if but when the camera becomes a dead monument when a power regulator fails or the operating system becomes corrupted.

If a SATA-style cable has to go around a bend, it is better to fold the flat cable across itself with a shallow ninety degree angle so that the flat of the cable assumes the curve rather than try to bend or stretch the cable edge-on into a curved path it will naturally and forcefully resist.
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carlomacchiavello

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Re: Ursa Mini Pro 4.6 G1 DROPPING FRAMES

PostTue Oct 08, 2019 9:29 pm

I had three different cFast to esata adapter to my startech boxes for ssd.
In that boxes I have 4 x San disk extreme pro ssd 480gb.
I never find issue from dng at 60p at 3:1 4.6k to any actual braw flavour.
Cable - box - ssd kind are all weak point, you must assure that all is the best.
Cable could give problem, box could have bad interface controller, ssd could have bad controller for cells and not keep speed for all recording time.


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Stephanie

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Re: Ursa Mini Pro 4.6 G1 DROPPING FRAMES

PostWed Oct 09, 2019 12:26 am

Thanks for the responses guys.

The SSds are Samsung Evo 860 250gb and 500gb.
They are on the compatible list as 2TB and above.
Could it be the SSDs are being overworked because of the write cache? But one time when it happened I had only just started shooting and I was only shooting on 2k Prores 422.

Yes my SSD adaptor has the cfast inserts and bridge cables. Since the blackmagic version uses the SDI ports I preferred getting this one.
Thanks that is a very good suggestion about taping the bridge cables. But is there a way to test if they are the culprit or not?

I am powering via V lock battery plate which goes on the back of the adaptor. It could potentially be the battery slippage issue because I have found my batteries do not click when I put them on the plate- could it be an issue in the process between the battery plate, adaptor and camera?
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rick.lang

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Re: Ursa Mini Pro 4.6 G1 DROPPING FRAMES

PostWed Oct 09, 2019 5:31 pm

Stephanie wrote:Thanks for the responses guys.

The SSds are Samsung Evo 860 250gb and 500gb.
They are on the compatible list as 2TB and above...


I think you have correctly answered your own question.


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robert Hart

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Re: Ursa Mini Pro 4.6 G1 DROPPING FRAMES

PostWed Oct 09, 2019 7:34 pm

I vaguely recall there may have been issues with the smaller Samsung EVO series SSDs and that the larger 1TB drives were okay.

If your smaller EVO drives are not specifically on the BM approved list, it means they didn't work well enough in testing by BM. Larger SSD drives apparently have a larger allocation of memory to the cache for sustained writing and are less likely to lay down.

Best to check with another responder who knows what he or she is talking about rather than take my word for it.

There is no way to test those plug-in adaptors except to immobilise them in the slots by taping the data cables firmly to the camera body, taping that battery to the holder with a wraparound of tape drawn tight as you take it around, going faith-based and just using the camera.
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Robert Niessner

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Re: Ursa Mini Pro 4.6 G1 DROPPING FRAMES

PostWed Oct 09, 2019 9:02 pm

The 250GB / 500GB drives have 3 / 4 GB of default cache and do extend that with intelligent turbo write to 12 / 22 GB of pseudo SLC cache. After that both models fall back to 300 MB/s sequential write, while the large capacity drives like 1TB stay at 500GB/s
Of course those write speeds are best case results, on average the large capacities reach ~400GB/s
The smaller ones most likely will be significantly lower on average.
Robert Niessner
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Uli Plank

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Re: Ursa Mini Pro 4.6 G1 DROPPING FRAMES

PostTue Oct 15, 2019 4:03 pm

Did you try both slots?
I found that my adapter works fine with the Startech in the rear slot, but drops frames in the front one.
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