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Question regards microSD cards and their speeds.
7050 19 2019-11-14
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IEdzus
lvl.1
Flight distance : 423369 ft
Ireland
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Hi guys,


After spending a while doing some research about SD cards, i have found something interesting. DJI recommends to use Micro SD cards that are rated for 30MB/s (Class 10 or V30) But a 4K video needs 60MB/s card speeds. And 2.7k would be around 45MB/s (refer to the photo on the bottom of the post)

The new Mavic Mini shoots video at:

  • Video Resolution
  • 2.7 K: 2720×1530 25/30 p
    FHD: 1920×1080 25/30/50/60 p

  • Max Video Bitrate
  • 40 Mbps



and under the recomended SD cards it says:


  • Recommended microSD Cards
  • 16 GB: SanDisk Extreme, Lexar 633x
    32 GB: Samsung Pro Endurance, Samsung Evo Plus, SanDisk Industrial, Sandisk Extreme V30 A1, SanDisk Extreme V30 A2, SanDisk Extreme Pro V30 A1, SanDisk Extreme Pro V30 A2, Lexar 633x, Lexar 667x
    64 GB: Samsung Pro Endurance, Samsung Evo Plus, SanDisk Extreme V30 A1, SanDisk Extreme V30 A2, Lexar 633x, Lexar 667x, Lexar 1000x, Lexar High Endurance, Toshiba EXCERIA M303 V30 A1, Netac Pro V30 A1
    128 GB: Samsung Pro Plus, Samsung Evo Plus, SanDisk Extreme V30 A1, SanDisk Extreme V30 A2, SanDisk Extreme Plus V30 A1, SanDisk Extreme Plus V30 A2, Lexar 633x, Lexar 667x, Lexar 1000x, Lexar High Endurance, Toshiba EXCERIA M303 V30 A1, Netac Pro V30 A1
    256 GB: SanDisk Extreme V30 A1, SanDisk Extreme V30 A2




So should'nt the Mavic Mini use a microSD card rated for V60 Video Speed Class?






2019-11-14
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pinkmenprints
Second Officer
Singapore
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Nice infographics there
2019-11-14
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jacksonnai
Captain
Malaysia
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Thanks for the information!
2019-11-15
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DJI Stephen
DJI team
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Hello and good day IEdzus. Thank you for sharing this informative information you have posted and shared. Great work and thank you for your support.
2019-11-15
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IEdzus
lvl.1
Flight distance : 423369 ft
Netherlands
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I would like some input from DJI side regards the SD cards and requirements for the DJI MAVIC MINI
2019-11-15
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IEdzus
lvl.1
Flight distance : 423369 ft
Ireland
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Still no reply from DJI, waiting for a clarification on this
2019-11-21
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fliptwister
lvl.1
Flight distance : 22516 ft
United States
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My experience has been that the U1, U3, V30, V60 speed classes don't necessarily equate to actual speeds. Ultimately you should choose a card based on real world speeds. This is a  web site I use which has real world speeds of cards:
https://havecamerawilltravel.com ... test-microsd-cards/

If you go down to the part of page which has the cards listed you will notice that there are a lot of cards with a sequential write speed speeds over 45 mb/sec or even 60 mb/sec. The second fasted card is only a U3 card but yet it has a sequential write speed speed of 256.3 mb/sec. You are probably better getting a card with at least 60 mb/sec speeds so you can use also on 4K devices. Many of those cards over 60 mb/sec are very reasonable in cost (at least here in US, not sure about Ireland). I use Samsung EVO Select micro SD cards in many of my devices (up to 4K) with no issues. The 128 gb Samsung EVO Select micro SD card costs $20 and it has a sequential write speed of 84.4 mb/sec.   
2019-11-21
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Knapweed
lvl.4
Canada
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It looks like you're confusing Mb/s and MB/s.
2019-11-21
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powerlordUK
lvl.1

United Kingdom
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yup. 40 mb/s = 40/8 = 5 MB/s

i.e. you'd really struggle to find a micro SD card these days that isn't fast enough for the MM.

The sdcard standard site's infographic is really unhelpful here I think as lots of people will make the same mistake. For example hardy any consumer equipment shoots 4k at more than 100mb/s.

that is 100/8 = 12.5MB/sec. easily achievable by most class 1 cards (which in reality exceed class 1).
2019-11-22
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IEdzus
lvl.1
Flight distance : 423369 ft
Ireland
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powerlordUK Posted at 11-22 03:51
yup. 40 mb/s = 40/8 = 5 MB/s

i.e. you'd really struggle to find a micro SD card these days that isn't fast enough for the MM.

Right, but when you look at the bit rate on a computer it says that MM shoots at 40MB/S and Phantom 3 SE is at 60mbs
2019-11-25
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djiuser_1BnE63N6VZKT
lvl.1

Germany
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Question: Toshiba exceria m303E   & Samsung Evo plus
I want to know which one has better build quality and how long will last
Toshiba m303e  has only 2 years warranty
2020-5-8
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m80116
Captain
Flight distance : 3264131 ft
Italy
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For my experience in testing and seeing performance ratings the two top dogs in this market are: SanDisk, Samsung. These two top brands are almost interchangeable with one another. Others may closely follow ore may be more specifically tailored (for example to professional).

I also have Toshiba cards, they're good... but despite similar specs not as quick as Samsung or SanDisk ones. Price wise I do believe Samsung quite often undercut SanDisk.
2020-5-8
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Geebax
Captain
Australia
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IEdzus Posted at 2019-11-21 15:04
Still no reply from DJI, waiting for a clarification on this

Dont waste your time, DJI do not reply to these questions, even the moderators just quote rthe same old placebo answers.

There is almost no point in examining the published specifications on SD cards, because almost all the companies lie about the specs, or simply quote figures to impress you. There is only one specification that is useful in comparing SD cards, and it is not one that any company publishes. That figure is SUSTAINED WRITE SPEED, and it means the speed of writing that can be maintained over an extended period of time. This figure is important because most consumer level cameras these days using MPEG encoding in a continuous program stream format. This format has to be written continuously to a memory destination, there is no ability to drop frames if the memory destination cannot write fast enough to keep up with the program stream. If the memory, or SD card, is not fast enough to keep writing continuously, the write process fails and the recording stops.
And in case you are somewhat technical and know about buffers, NO, there is no buffer in these cameras because of the huge size of video files these days. A buffer in a camera system is very useful for single shots, particularly a sequence of shots, but it would quickly be over-run in video mode.

In my experience, the only way to choose SD cards is to buy the top level, and therefore top price card in the first place, and to frequently format them in the camer to keep the cards free of messy hidden files that can slow down the writing process. The best card is a Sandisk Extreme Pro card. Not the Plus variety or any other version. It costs more, but it works as long as you bought a genuine Sandisk card and not a counterfeit one.





2020-5-8
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Geebax
Captain
Australia
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IEdzus Posted at 2019-11-25 04:10
Right, but when you look at the bit rate on a computer it says that MM shoots at 40MB/S and Phantom 3 SE is at 60mbs

No, the specs on DJI's web site say the MM shoots at a Maximum Video Bitrate of 40mb/s, not MB/s (which is 8 times faster. An upper case 'B' means bytes, whereas a lower case 'b' means bits.
2020-5-8
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m80116
Captain
Flight distance : 3264131 ft
Italy
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Just FYI: since MM bitrate is fairly low I've tried with other cards that should be well within spec about sustained write speed and despite errors it manages to write one video perfectly fine... the next one refuses to follow suit. It seems like there's something about older cards that DJI actively enforce not to be used with the MM.
2020-5-8
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Geebax
Captain
Australia
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m80116 Posted at 5-8 17:35
Just FYI: since MM bitrate is fairly low I've tried with other cards that should be well within spec about sustained write speed and despite errors it manages to write one video perfectly fine... the next one refuses to follow suit. It seems like there's something about older cards that DJI actively enforce not to be used with the MM.

That can happen when the card is on the borderline of speed. A classic case is the Sandisk Extreme Plus series of cards, they would work OK for a while in t5he P3 series aircraft, then, as they filled up with hidden files, they would stop recording suddenly.
2020-5-8
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IEdzus
lvl.1
Flight distance : 423369 ft
Ireland
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When you move the videos to your PC for video editing under the details you can see the bit rate which reads at 40 MB/s so a 30 MB/s card wouldn't be enough then?
2020-5-8
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djiuser_267jcyL97zif
lvl.4
Flight distance : 15738737 ft
Bulgaria
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The video is about 40Mb/s or 5MB/s.

The still images are about 5.5 - 7.5MB per shot. So if you shoot series of photos at 1 second rate, you will need writing speed at-least 8MB/s. So you are going into the V10 class.

However DJI knows, that SD card manufactures are lying about their writing speeds. So they put V30 to be sure you will not have problems to complain about.
2020-5-12
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Eric Coyler
New

Bangladesh
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Which one would be better? Samsung evo select or evo plus?
2021-1-24
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Eric Coyler
New

Bangladesh
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Nice infographic.
2021-1-24
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