Pocket 4k stopped seeing SD card or recording to SSD

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igrafix

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Pocket 4k stopped seeing SD card or recording to SSD

PostWed Feb 17, 2021 3:03 pm

I have a weird problem with my Pocket 4K camera.

For a few days I was using the same SD card to record video with no problem (at 4k ProRes), but today when I powered up the camera, it doesn't see the card anymore.
I tried the card on 2 computers, both see it without any problem (and both can read and write to it), I tried formatting it to both HFS+ and ExFAT, nothing changes.

The camera does recognize my external SSD (Samsung T7), it can format it, but it won't record to it. (the dropped frame icon keeps blinking, even when I set the camera to the lowest possible settings)

Is there anything I can do to fix this?
(I'd prefer to not have to buy a cfast card to try out, as I have almost no more budget left)

Camera software version is 6.9.6.
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Spencer Acoustics

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Re: Pocket 4k stopped seeing SD card or recording to SSD

PostMon Feb 22, 2021 10:44 pm

I have a P4K and a Samsung T5 and experience similar issues. The camera does not always recognize the T5 and I have unplug it and plug it back in until it finally recognizes the T5. However, that is where our problems differ. Once the camera finally recognizes the card it will record, play, format, etc. just fine....unless it looses connection to the camera. It can be frustrating.

I hope that your problem is a formatting issue because I am planning on buying a T7 in a few weeks. Maybe try a different usb cable, possibly it is causing the issue.

Good luck,
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carlomacchiavello

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Re: Pocket 4k stopped seeing SD card or recording to SSD

PostMon Feb 22, 2021 10:58 pm

Spencer Acoustics wrote:I have a P4K and a Samsung T5 and experience similar issues. The camera does not always recognize the T5 and I have unplug it and plug it back in until it finally recognizes the T5. However, that is where our problems differ. Once the camera finally recognizes the card it will record, play, format, etc. just fine....unless it looses connection to the camera. It can be frustrating.

I hope that your problem is a formatting issue because I am planning on buying a T7 in a few weeks. Maybe try a different usb cable, possibly it is causing the issue.

Good luck,
T7 is rubbish and not work with bmd
Many people tested, it had low quality memory and bad controller. Don’t waste your money


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robedge

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Re: Pocket 4k stopped seeing SD card or recording to SSD

PostMon Feb 22, 2021 10:59 pm

igrafix wrote:
The camera does recognize my external SSD (Samsung T7), it can format it, but it won't record to it. (the dropped frame icon keeps blinking, even when I set the camera to the lowest possible settings)


Spencer Acoustics wrote:
I hope that your problem is a formatting issue because I am planning on buying a T7 in a few weeks.



The Samsung T7 SSDs are not on the Blackmagic approved list and they don't work with the Pocket cameras. If you search the forum, you will find several threads on the issue.

This is the sticky thread in the forum on the approved list: viewtopic.php?f=2&t=95785

Edit: Looks like Carlo and I posted at the same time :)
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Re: Pocket 4k stopped seeing SD card or recording to SSD

PostTue Feb 23, 2021 9:46 am

Yeah, the T7 are so called "DRAM-less" SSD controllers.

The T5 on the other end had a 1Gbyte DRAM internally to serve has read-cache and also absorb any write peak.
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carlomacchiavello

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Re: Pocket 4k stopped seeing SD card or recording to SSD

PostTue Feb 23, 2021 10:29 am

robedge wrote:Edit: Looks like Carlo and I posted at the same time :)


we are in sinc :-D
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Re: Pocket 4k stopped seeing SD card or recording to SSD

PostTue Feb 23, 2021 10:35 am

and do not use a SD card and a SSD at the same time
booth uses the same controllerport
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rick.lang

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Re: Pocket 4k stopped seeing SD card or recording to SSD

PostWed Feb 24, 2021 7:42 pm

@igrafix
What exact SD card are you using? I assume you are formatting the card in the camera, which I’d normally recommend, but you might try formatting in your card reader using the computer.
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igrafix

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Re: Pocket 4k stopped seeing SD card or recording to SSD

PostThu Feb 25, 2021 8:10 pm

The card is ADATA PREMIER ONE SDXC UHS-II U3 - as far as I know it's not on the recommended cards list - and I wouldn't be surprised if it didn't work at all - but it did, perfectly, for a few days, until it stoppped. It was formatted in the camera initially, now it's reformatted using a computer, since the camera doesn't recognize it so it also can't format it.

For now I kind of solved the most pressing issue - the card still isn't recognized, but I managed to exchange the T7 SSD for T5 - and that one works great, so the camera is usable as long as I use it with the external ssd. :)
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rick.lang

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Re: Pocket 4k stopped seeing SD card or recording to SSD

PostFri Feb 26, 2021 1:16 am

That is strange behaviour for the card but good to see your SSD problem is resolved. Depending on how much you recorded to the card when it was working perfectly, there is a possible explanation but I’m speculating. All consumer cards now are MLC, multi-level cells. On a fresh card, it’s easier to write up to about 50% of the capacity as that is written to the first level of cells. It has to do more work when writing to the second level which might precipitate a failure to keep up with the data rate.

Once the card has been used fully and you do a ‘quick’ format (that only resets the file directory), it takes more work to write to the first level again as the process to perform the write must also erase the former contents of the cell. A ‘deep’ format that writes to every cell would get around that extra step in the workflow.
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smunaut

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Re: Pocket 4k stopped seeing SD card or recording to SSD

PostFri Feb 26, 2021 7:39 am

That's not how multi-level works ... you don't write the "levels" independently.

Multi-level (really a bad name) means each cell stores 4 different charge levels, nominally : 0, 0.33, 0.66, 1.0 and thus allow to store 2 bits per cell. It's slower than SLC because of the complexity of programming those exact charge levels. Imagine for a SLC only having 0 and 1, you can just dump a bunch of charge to program it without caring, you can't really "go over" ... for MLC, you need to be more careful hence increase write time.

Now, the explanation for why some cards write faster can be two-fold:

* Some card, to boost write speed, will use part of their MLC array as a SLC array writing only 0.0 and 1.0 into it and just marking those sectors as "to be consolidated into MLC later when I have time". Obviously in a continuous video write scenario the "when I have time" part doesn't happen all that often and you might hit issues after some recording time.

* You can't overwrite previously written data in a sector, you have to erase the whole sector then rewrite it in full. Erasing takes a lot of time. So usually what a card will do is pick any random empty sector write it (possible with a mix of new data and old data that wasn't change) and "substitute" it. The old sector is just set aside and marked "to be erased whenever I have time".

It even gets more complex because normal file operations (create / delete files), the sd card has usually no idea if a sector is still in use or not. As far as it's concerned once it has been written to 1 time, the sector is used and it can't ever erase it pre-emptively. To solve that in SSD the "TRIM" protocol was invented so the OS/filesystem layer could tell the storage device "Ok, those blocks, I'm not using them anymore" and so the SSD/SD can pre-emptively erase them to prepare future writes.

That's also why formatting in the camera is probably a better idea. Most likely (I can't check but it would make sense), the camera instead of writing zeros to the card (which as far as the card is concerned doesn't mean the sector can be erased), sends the special SD card command to the card telling it the sectors are not in use and can be recovered. Not all PC reader can send that command (the usb ones I have can't ... only the one I have built in my PC can for instance).
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rick.lang

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Pocket 4k stopped seeing SD card or recording to SSD

PostFri Feb 26, 2021 6:49 pm

Thanks for the greater detail. I was passing on a description from Tom’s Hardware I read many years ago when MLC were gradually replacing SLC. A better name could have been MCC Multi Charge Cell.
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