Please select Into the mobile phone version | Continue to access the computer ver.
Advice on SD card choice
12
19119 64 2017-8-6
Uploading and Loding Picture ...(0/1)
o(^-^)o
Swedrone
Captain
Flight distance : 14066975 ft
  • >>>
Sweden
Offline

MARSAN Posted at 2017-8-8 02:57
Provided your devices are running USB 3.0 and not USB 2.0.

regardless of usb version you don´t want to waste time I think.
2017-8-8
Use props
calmari
lvl.4
Flight distance : 64944 ft
United Kingdom
Offline

MARSAN Posted at 2017-8-8 02:42
There seems to be contradiction.
The SanDisk memory card shown in DJI Susan's table can write data at a whopping speed of 60 MB/s, yet the Mavic has a "Max Video Bitrate" of only 7.5 MB/s (60 Mbps).
That is a huge difference of 8 to 1.

Yes it can write at that speed but in terms of a 'guarantee', the minimum sustained write speeds are what a lot of manufacturers seem to fall back on.

Class 10 & UHS-I class1 = 10MB/s and UHSI class 3 = 30MB/s.
2017-8-8
Use props
MARSAN
First Officer
Flight distance : 966978 ft
Belgium
Offline

Swedrone Posted at 2017-8-8 03:01
regardless of usb version you don´t want to waste time I think.

Have a look at this article:
https://www.howtogeek.com/179803 ... -your-flash-drives/
2017-8-8
Use props
MARSAN
First Officer
Flight distance : 966978 ft
Belgium
Offline

calmari Posted at 2017-8-8 03:01
Yes it can write at that speed but in terms of a 'guarantee', the minimum sustained write speeds are what a lot of manufacturers seem to fall back on.

Class 10 & UHS-I class1 = 10MB/s and UHSI class 3 = 30MB/s.

But why use a total data overkill write speed of 8 to 1?
It would be similar to using a Formula 1 race car to drive to your local baker in your village.
2017-8-8
Use props
calmari
lvl.4
Flight distance : 64944 ft
United Kingdom
Offline

MARSAN Posted at 2017-8-8 03:16
But why use a total data overkill write speed of 8 to 1?
It would be similar to using a Formula 1 race car to drive to your local baker in your village.

Simple answer - I think the reason this card is being mentioned is because it is the one DJI sells, I guess they know it is more than acceptable for their products and as I said earlier, it is a one size fits all, for all of their products, so keeps things simple.

Taking into account language barriers and English not necessarily being everyone's first language, the 'recommendation' above from Susan I certainly don't take as a solid recommendation of the card you 'must use'.
Even at 30MB/s, that is still overkill for what the Mavic can currently actually output in my opinion.
2017-8-8
Use props
MARSAN
First Officer
Flight distance : 966978 ft
Belgium
Offline

calmari Posted at 2017-8-8 04:16
Simple answer - I think the reason this card is being mentioned is because it is the one DJI sells, I guess they know it is more than acceptable for their products and as I said earlier, it is a one size fits all, for all of their products, so keeps things simple.

Taking into account language barriers and English not necessarily being everyone's first language, the 'recommendation' above from Susan I certainly don't take as a solid recommendation of the card you 'must use'.

And here we are back to square one with that mysterious "Max Video Bitrate" of only 7.5 MB/s (60 Mbps).
Someone else, Dancopter, who thinks that it is the transmission rate between the Mavic and the RC/phone combo:
http://forum.dji.com/forum.php?m ... mp;page=1#pid903780
2017-8-8
Use props
MARSAN
First Officer
Flight distance : 966978 ft
Belgium
Offline

Albatros24 Posted at 2017-8-8 03:01
@MARSAN
"soit 3840 x 2160 x 60 = 497.664.000 bps ou 62.208.00 octets par seconde ou 60 Mo./s."
This is at the output of the sensor ! But ALL is compressed in MOV or MP4 and then obtains a bit rate of 60 M bits /s.

Then what is the point of buying an ultra fast memory card with a write speed of 60 MB/s when only a mere 7.5 MB/s is necessary?
2017-8-8
Use props
BumblerBee
First Officer
Flight distance : 639764 ft
Norway
Offline

60Mbps is the bitrate of the 4K footage. You can see that using BitRate Viewer or in the Detail properties of the video file.

As I mentioned before, UHS-1 (or Class 10) rated SD card is more than enough for Mavic.

See specs here:
https://www.sdcard.org/developers/overview/speed_class/
2017-8-8
Use props
calmari
lvl.4
Flight distance : 64944 ft
United Kingdom
Offline

MARSAN Posted at 2017-8-8 04:33
Then what is the point of buying an ultra fast memory card with a write speed of 60 MB/s when only a mere 7.5 MB/s is necessary?

To be fair, you are one of the ones pushing the U3 and 30MB/s write speeds
2017-8-8
Use props
calmari
lvl.4
Flight distance : 64944 ft
United Kingdom
Offline

MARSAN Posted at 2017-8-8 04:27
And here we are back to square one with that mysterious "Max Video Bitrate" of only 7.5 MB/s (60 Mbps).
Someone else, Dancopter, who thinks that it is the transmission rate between the Mavic and the RC/phone combo:
http://forum.dji.com/forum.php?mod=viewthread&tid=108156&page=1#pid903780

I think he is saying the exact opposite of that actually.
2017-8-8
Use props
MARSAN
First Officer
Flight distance : 966978 ft
Belgium
Offline

calmari Posted at 2017-8-8 05:59
I think he is saying the exact opposite of that actually.

Place his post in the correct context.
2017-8-8
Use props
MARSAN
First Officer
Flight distance : 966978 ft
Belgium
Offline

calmari Posted at 2017-8-8 05:56
To be fair, you are one of the ones pushing the U3 and 30MB/s write speeds

Did you miss this post?
http://forum.dji.com/forum.php?m ... &fromuid=863102
2017-8-8
Use props
eyeloveteeth
lvl.4
Flight distance : 1015397 ft
  • >>>
United States
Offline

i've been using a 256GB Sandisk class 10 card with no issues. but i am also fairly new -

I have a different question - so if you record in 4k (which i think 99% of the time you will) - what are you recording on the DJI goggles? I haven't put any cards in, weather got bad for me to try again - but is the SD card on the Goggles recording at the 720p @ 30FPS or is it recording the 4k?


Also, why does it down convert to 720 instead of keeping it at 1080?
2017-8-8
Use props
calmari
lvl.4
Flight distance : 64944 ft
United Kingdom
Offline

MARSAN Posted at 2017-8-8 06:27
Place his post in the correct context.

Well the OP is looking for an explanation as to why he doesn't have 4K footage on his Samsung.

DJI explains that the footage from Mavic to the phone is only 1080p max

@Dancopter makes his comment that I interpret as it's difficult to 'transmit live 4K footage at 60 mbps over several kilometres'

'Trying to transmit live 4K footage at 60 mbps over several kilometres is asking for alot'
2017-8-8
Use props
calmari
lvl.4
Flight distance : 64944 ft
United Kingdom
Offline


No I didn't. I think my post is accurate. Susan hasn't said you 'need' U3. She has 'recommended' a card.
2017-8-8
Use props
MARSAN
First Officer
Flight distance : 966978 ft
Belgium
Offline

calmari Posted at 2017-8-8 08:40
No I didn't. I think my post is accurate. Susan hasn't said you 'need' U3. She has 'recommended' a card.

Yes, I know she recommended that card, what else should she do?
2017-8-8
Use props
calmari
lvl.4
Flight distance : 64944 ft
United Kingdom
Offline

MARSAN Posted at 2017-8-8 08:57
Yes, I know she recommended that card, what else should she do?

I completely miss the point you are trying to make then. I give up. Let's wait and hear if DJI expand on the questions posed.
2017-8-8
Use props
MARSAN
First Officer
Flight distance : 966978 ft
Belgium
Offline

calmari Posted at 2017-8-8 08:38
Well the OP is looking for an explanation as to why he doesn't have 4K footage on his Samsung.

DJI explains that the footage from Mavic to the phone is only 1080p max

Conclusion?
That mysterious "Max Video Bitrate" of 60Mbps has nothing to do with writing data to the Mavic's memory card?
I hope DJI will clarify.
2017-8-8
Use props
MARSAN
First Officer
Flight distance : 966978 ft
Belgium
Offline

calmari Posted at 2017-8-8 09:00
I completely miss the point you are trying to make then. I give up. Let's wait and hear if DJI expand on the questions posed.

<sigh>
Once again, it is this inexplicable gigantic difference of recommending a memory card that can write at 60 MB/s when the Mavic can only (apparently!) write at 7.5 MB/s.
I wouldn't mind if somebody can clarify this.
2017-8-8
Use props
calmari
lvl.4
Flight distance : 64944 ft
United Kingdom
Offline

MARSAN Posted at 2017-8-8 09:00
Conclusion?
That mysterious "Max Video Bitrate" of 60Mbps has nothing to do with writing data to the Mavic's memory card?
I hope DJI will clarify.

Noooo!!!

Conclusion. He's saying the opposite, the 60Mbps is what is used to write to the card because it is a tall order to send it via wireless over kilometers back to the phone so a lower bitrate is used to send the 720 and 1080 back to the phone.

Look at the bitrates of a 4K video you have recorded. They will all be around 60000kbps.
2017-8-8
Use props
calmari
lvl.4
Flight distance : 64944 ft
United Kingdom
Offline

MARSAN Posted at 2017-8-8 09:06
Once again, it is this inexplicable gigantic difference of recommending a memory card that can write at 60 MB/s when the Mavic can only (apparently!) write at 7.5 MB/s.
I wouldn't mind if somebody can clarify this.

Well I know why I think they have done it, you obviously think differently.
2017-8-8
Use props
MARSAN
First Officer
Flight distance : 966978 ft
Belgium
Offline

calmari Posted at 2017-8-8 09:07
Noooo!!!

Conclusion. He's saying the opposite, the 60Mbps is what is used to write to the card because it is a tall order to send it via wireless over kilometers back to the phone so a lower bitrate is used to send the 720 and 1080 back to the phone.

Quote:
"Trying to transmit live 4K footage at 60 mbps over several kilometres is asking for alot!"
Unquote

Where exactly did he mention a card in his text?
2017-8-8
Use props
MARSAN
First Officer
Flight distance : 966978 ft
Belgium
Offline

calmari Posted at 2017-8-8 09:10
Well I know why I think they have done it, you obviously think differently.

I am merely stating the problem, not what I think, but I would like that someone clarifies this.
2017-8-8
Use props
calmari
lvl.4
Flight distance : 64944 ft
United Kingdom
Offline

MARSAN Posted at 2017-8-8 09:17
Quote:
"Trying to transmit live 4K footage at 60 mbps over several kilometres is asking for alot!"
Unquote

Why would he mention a card? He is talking about transmitting the footage from the drone back to a phone, no card involved. If he is talking about transmitting from the phone to the card then 'several kilometers' doesn't even come in to it.
2017-8-8
Use props
calmari
lvl.4
Flight distance : 64944 ft
United Kingdom
Offline

calmari Posted at 2017-8-8 09:19
Why would he mention a card? He is talking about transmitting the footage from the drone back to a phone, no card involved. If he is talking about transmitting from the phone to the card then 'several kilometers' doesn't even come in to it.

Sorry, edit time expired and then it wouldnt let me post because I had hit a 'POST LIMIT.

The last sentence should read

'If he is talking about transmitting from the Mavic to the card then 'several kilometers' doesn't even come in to it.'
2017-8-8
Use props
12
Advanced
You need to log in before you can reply Login | Register now

Credit Rules