Micro SD Card UHS grade requirement question

[vindibona1]

As I'm reading the MM instructions it says (regarding micro SD) that it REQUIRES a UHS grade 3 card. At this time I have 128gb GRADE 1 cards. Will there be a problem using them. Will increasing the cache substitute for a card that might record faster? Thoughts/experiences? TIA

 

[Pushkur]

As I'm reading the MM instructions it says (regarding micro SD) that it REQUIRES a UHS grade 3 card. At this time I have 128gb GRADE 1 cards. Will there be a problem using them. Will increasing the cache substitute for a card that might record faster? Thoughts/experiences? TIA

Samsung Extreme Pro is best for 4k, i guess you can get away with lower spec for the Mini resolution.

 

[BillW]

I had to buy a SanDisk class 3 card after I got the Mini.
I got a card error when I put in two other cards I already had.
It just didn't want to work.

 

[BadWolf1]

A quick check of my videos says that in 2.7K /30 fps mode the data rate is about 40 Mbyte/sec so if you want to shoot video you need a card that can sustain that . The cache on the phone is just a local, lower quality copy of what's on the SD card, so it's not going change that. Memory is so cheap these days I'd get a new card.

 

[RogerDH]

I accidentally used a Class 10 (non-UHS) card once and it worked okay, and I haven't had any problem using U1 cards except for one off-brand. You don't need U3 for 2.7K video, but if you're getting a new card, I'd recommend getting one anyway -- you may need it if 4K is in your future, and anyway it'll upload faster.

 

[Deleted member 103366]

32G Samsung evo U1 here and no problems but I am shooting at 1080 and not 2.7k

 

[BadWolf1]

I accidentally used a Class 10 (non-UHS) card once and it worked okay, and I haven't had any problem using U1 cards except for one off-brand. You don't need U3 for 2.7K video, but if you're getting a new card, I'd recommend getting one anyway -- you may need it if 4K is in your future, and anyway it'll upload faster.

A quick note if you're on windows. If you start either the command prompt or Windows PowerShell as admin (from the [win] [x] menu) and run
winsat disk -drive D:
(where D is the drive letter assigned to the card) you can can the read and write performance for that card - you'll get random reads (jumping about reading here, there and everywhere), sequential reads (like reading a big video file) and sequential writes (writing video).
I have multiple San disk cards, one is comfortably fastest for writes, but one of the others is fastest for reads but can't write fast enough for the drone's video .
So although "Get a new card ... " is basically sound advice it is not guaranteed to upload faster.

 

[vindibona1]

A quick note if you're on windows. If you start either the command prompt or Windows PowerShell as admin (from the [win] [x] menu) and run
winsat disk -drive D:
(where D is the drive letter assigned to the card) you can can the read and write performance for that card - you'll get random reads (jumping about reading here, there and everywhere), sequential reads (like reading a big video file) and sequential writes (writing video).
I have multiple San disk cards, one is comfortably fastest for writes, but one of the others is fastest for reads but can't write fast enough for the drone's video .
So although "Get a new card ... " is basically sound advice it is not guaranteed to upload faster.

I sort of get the gist of what you're saying. Do you have to have data on the card to be able to get the read/write speeds? What do you type exactly after you get the windows prompt?

I suppose I'll find out if a U1 is good enough as I have a new unused Sandisk Ultra 128 and a Samsung 32 used once- as shown below. Hopefully they will be fast enough even at 2.7k. But again... does increasing the cache help?

 

[RogerDH]

I sort of get the gist of what you're saying. Do you have to have data on the card to be able to get the read/write speeds? What do you type exactly after you get the windows prompt?

I suppose I'll find out if a U1 is good enough as I have a new unused Sandisk Ultra 128 and a Samsung 32 used once- as shown below. Hopefully they will be fast enough even at 2.7k. But again... does increasing the cache help?
View attachment 105694

No, the cache is just captured from the live stream to your phone, so it has no effect on what's happening on the Mini.

I'd expect both of those cards to work.

 

[vindibona1]

No, the cache is just captured from the live stream to your phone, so it has no effect on what's happening on the Mini.

I'd expect both of those cards to work.

Thanks. I have no idea how that stuff works. I suppose I'll find out.

 

[Dave Maine]

Ignoring the speed requirements is just asking for annoying, intermittent or not troubles. Flight time is expensive. Why jeopardize it with inadequate hardware?

 

[vindibona1]

Ignoring the speed requirements is just asking for annoying, intermittent or not troubles. Flight time is expensive. Why jeopardize it with inadequate hardware?

I understand your point. But I already have 3 cards with UHS 1. I haven't received my MM yet, due to come on Friday according to UPS tracking. I am just trying to understand video requirement that I was totally unaware of before. I record into my Canon 5D Mark III perfectly well with these cards. But again, until now I've not paid any attention to card speed requirements and just trying to learn.

 

[Km5er]

As I'm reading the MM instructions it says (regarding micro SD) that it REQUIRES a UHS grade 3 card. At this time I have 128gb GRADE 1 cards. Will there be a problem using them. Will increasing the cache substitute for a card that might record faster? Thoughts/experiences? TIA

You will be fine for photos. But for video you need a V30 (equivalent to U3) card. Nothing you can do will make the U1 card appropriate although some U1 cards may work...maybe...maybe not.

 

[Km5er]

I understand your point. But I already have 3 cards with UHS 1. I haven't received my MM yet, due to come on Friday according to UPS tracking. I am just trying to understand video requirement that I was totally unaware of before. I record into my Canon 5D Mark III perfectly well with these cards. But again, until now I've not paid any attention to card speed requirements and just trying to learn.

Full explanation:
‘Speed Class’ refers to the absolute minimum sustained write speeds. Cards can be rated as Class 2 (minimum write speed of 2MB/s), Class 4 (4MB/s), Class 6 (6MB/s) or Class 10 (10MB/s). The next rating is the UHS Speed Class. This stands for Ultra High Speed and refers to minimum sustained writing performance for recording video. UHS came about due to 4K-capable video devices needing faster write speeds. There are two UHS Speed Classes, UHS Speed Class 1 and UHS Speed Class 3. UHS Speed Class 1 supports a minimum 10MB/s write speed, whereas UHS Speed Class 3 supports at least 30MB/s write speed. The UHS Speed Class is denoted by either a 1 or 3 inside of a bucket U symbol. As a rule of thumb, 4K-capable camcorders will usually require at least a U3 rated SD card. Extremely high-resolution video (4 or 8K), demanded even faster cards and this is provided by V class which range from 6 to 90. The number represents MB/sec. Confused yet? Keep reading. So, going from fastest to slowest with these numbers it is V90, V60, V30 (which is equal to U3) V10 (which is equal to U1 and Speed Class 10). The remaining are not worth considering.

Also, for drones ignore A1 and A2 ratings and just pay attention to V ratings. The A ratings are for application extensive operations such as smartphones and mobile gaming consoles. This is the Application Performance Class Specification. These cards essentially extend the memory of these devices. The apps that run on these devices interact with memory space differently. Rather than a stream of sequential data (think video), they write a lot of small chunks of data wherever there's space available. That's known as random read/write (compared to sequential read/write that's important for video). A card that is suitable for random reading and writing may not be suitable for sequential reading and writing. The A1 and A2 cards have different random read and write ratings but have the same minimum sequential write speed of 10 megabytes per second. This speed is equivalent to the Class 10 video speed rating. The Class 10 rating is about the same is the V10 rating. The V10 rating is too slow for your drone.

So, the bottom line for your drone camera (at least DJI drones) you need a minimum V30 card (or U3). The card may also have other ratings (Such as A or U) but if it says V30 or better you are good. And as always, the best bet is to see what the manufacturer recommends/requires. But keeping it simple = V30 minimum.

 

[shorttimer]

A quick check of my videos says that in 2.7K /30 fps mode the data rate is about 40 Mbyte/sec so if you want to shoot video you need a card that can sustain that . The cache on the phone is just a local, lower quality copy of what's on the SD card, so it's not going change that. Memory is so cheap these days I'd get a new card.

I believe you mean 40 Mbps, 40 Mega bits per second and not 40 MBps, 40 Mega Bytes per second. Big difference.

 

[vindibona1]

Full explanation:
‘Speed Class’ refers to the absolute minimum sustained write speeds. Cards can be rated as Class 2 (minimum write speed of 2MB/s), Class 4 (4MB/s), Class 6 (6MB/s) or Class 10 (10MB/s). The next rating is the UHS Speed Class. This stands for Ultra High Speed and refers to minimum sustained writing performance for recording video. UHS came about due to 4K-capable video devices needing faster write speeds. There are two UHS Speed Classes, UHS Speed Class 1 and UHS Speed Class 3. UHS Speed Class 1 supports a minimum 10MB/s write speed, whereas UHS Speed Class 3 supports at least 30MB/s write speed. The UHS Speed Class is denoted by either a 1 or 3 inside of a bucket U symbol. As a rule of thumb, 4K-capable camcorders will usually require at least a U3 rated SD card. Extremely high-resolution video (4 or 8K), demanded even faster cards and this is provided by V class which range from 6 to 90. The number represents MB/sec. Confused yet? Keep reading. So, going from fastest to slowest with these numbers it is V90, V60, V30 (which is equal to U3) V10 (which is equal to U1 and Speed Class 10). The remaining are not worth considering.

Also, for drones ignore A1 and A2 ratings and just pay attention to V ratings. The A ratings are for application extensive operations such as smartphones and mobile gaming consoles. This is the Application Performance Class Specification. These cards essentially extend the memory of these devices. The apps that run on these devices interact with memory space differently. Rather than a stream of sequential data (think video), they write a lot of small chunks of data wherever there's space available. That's known as random read/write (compared to sequential read/write that's important for video). A card that is suitable for random reading and writing may not be suitable for sequential reading and writing. The A1 and A2 cards have different random read and write ratings but have the same minimum sequential write speed of 10 megabytes per second. This speed is equivalent to the Class 10 video speed rating. The Class 10 rating is about the same is the V10 rating. The V10 rating is too slow for your drone.

So, the bottom line for your drone camera (at least DJI drones) you need a minimum V30 card (or U3). The card may also have other ratings (Such as A or U) but if it says V30 or better you are good. And as always, the best bet is to see what the manufacturer recommends/requires. But keeping it simple = V30 minimum.

Thanks. I suppose I'll have to do a test run on my existing cards as I would prefer not to have to purchase additional cards if practically unnecessary. Sandisk cards have always been reliable and seem to be a good brand. Perhaps I'll order a 64GB class 3 card from Amazon that I can return if not needed.

Is there a way to test the actual write speed of a card in my computer? I have a micro SD reader that is USB3 and a very fast (Alienware) PC (win10)

 

[BadWolf1]

I sort of get the gist of what you're saying. Do you have to have data on the card to be able to get the read/write speeds? What do you type exactly after you get the windows prompt?

I suppose I'll find out if a U1 is good enough as I have a new unused Sandisk Ultra 128 and a Samsung 32 used once- as shown below. Hopefully they will be fast enough even at 2.7k. But again... does increasing the cache help?

Card can be empty or nearly full. The test creates a file and deletes it when it has finished.

On my machine the SD card is drive E: so I use this

winsat disk -drive e:

If it opens in a new window you need start the prompt as admin, otherwise you lose the results !

To the best of my knowledge, there is no caching of writes to the SD card inside the drone, whatever buffer there is can't be changed - the camera's sensor is sending raw data to the on-board processor, which converts to MP4 file format and writes to the card. The might be a second or two in memory - but you can imagine if it could only write at half the speed it shoots and had a couple of GB in memory and needed two minutes after landing to write it that wouldn't be good.

There is local caching on the phone... if you mean the option on advanced photo settings in the app - it's a lower quality version downloaded in-flight. changing that won't change what happens on-board

 

[Km5er]

I accidentally used a Class 10 (non-UHS) card once and it worked okay, and I haven't had any problem using U1 cards except for one off-brand. You don't need U3 for 2.7K video, but if you're getting a new card, I'd recommend getting one anyway -- you may need it if 4K is in your future, and anyway it'll upload faster.

You need to follow the spec. Spec requires V30 which is same as U3.

 

[BadWolf1]

I believe you mean 40 Mbps, 40 Mega bits per second and not 40 MBps, 40 Mega Bytes per second. Big difference.

Yes. I should have done a sanity check. Here's Windows reporting ~ 40,000kbps. 40 MBits - 5 MBytes so 29 seconds is 145MBytes. 40MBytes a second would be 1.2GB in 30 seconds.
.



In my defence the read speed of this card is in the 10s of MBytes. Just copying a 1.25GB MP4 from card to SSD drive runs at about 130 Mbytes per sec (i.e. about 10 seconds to copy the file) So the speed of the card is something like 10 times the speed. Winsat reports a slower - if told to use bigger blocs it goes faster but not up to the speed of a normal file copy.


What's curious is why the stated requirements for card are set quite so fast - this is a sandisk extreme card. BTW. badged as U3 / V30 , but based on the bit rate of the video U1 should be enough, even for 4K at 30FPS.
The spec says not.

 

[Km5er]

No, the cache is just captured from the live stream to your phone, so it has no effect on what's happening on the Mini.

I'd expect both of those cards to work.

These cards are not adequate. Both are U1.