Extreme cards( micro sd) vs other cards

thekingomenshow · Oct 13, 2016

Can anyone tell me if it's ok to use anything less than 90mbps speed micro sd/sd cards for 4K vids?

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msinger · Oct 13, 2016

People seem to have the best results with memory cards that write at least at 40MB/s. You can find a list of commonly used memory cards matching that spec here.

Meta4 · Oct 13, 2016

thekingomenshow said:
Can anyone tell me if it's ok to use anything less than 90mbps speed micro sd/sd cards for 4K vids?

It's OK to use any card that meets DJI specs:
Supported SD Card TypesMicro SD
Max capacity: 64 GB. Class 10 or UHS-1 rating required
Using a faster, more expensive card won't be any better as the write speed is determined by the Phantom - not the card.

msinger · Oct 13, 2016

With that said, it's also important to note that DJI ships memory cards that write at 40MB/s with the Phantom. They go above and beyond their specs for some reason.

alokbhargava · Oct 13, 2016

Be aware of cheap SD cards. Though they match the specs but fail to really work. Go for reputed make like Lexar, Samsung, SanDisk, .......

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With The Birds · Oct 13, 2016

You need less than 8 Mbyte write speed for 4K video. Spending more on higher spec cards pays off when it comes to copying from your card to a PC or other device.

Peter Galbavy · Oct 14, 2016

Also, beware of the headline speed - it is almost always the read speed when what you need to know is the write speed. Technically any Class 10 card or better is enough - the video bit rate is 60Mbps - around 6MBps - but I am using only UHS Class 3 cards - which are rated for 30MBps (~300Mbps).

Here, "B" is bytes, "b" is bits and, accounting for overhead a 10x multiplier about right for simple calculations.

thekingomenshow · Oct 16, 2016

Thank you guys. Your informative inputs are my oxygen.

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With The Birds · Oct 16, 2016

Peter Galbavy said:
Also, beware of the headline speed - it is almost always the read speed when what you need to know is the write speed. Technically any Class 10 card or better is enough - the video bit rate is 60Mbps - around 6MBps - but I am using only UHS Class 3 cards - which are rated for 30MBps (~300Mbps).

Here, "B" is bytes, "b" is bits and, accounting for overhead a 10x multiplier about right for simple calculations.

+1 for throwing 25% overhead in the mix. We need to allow for some brands where the quoted specs are a little on the optimistic side.

RémyHeli · Oct 16, 2016

Note also some cards with 16go have lower speed/specs than same brand and model but 32 or higher.

Wondering also possible benefit with high speed cards: less frames lost during transition to next file segment?

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John Locke · Oct 16, 2016

Peter Galbavy said:
I am using only UHS Class 3 cards - which are rated for 30MBps (~300Mbps).

Here, "B" is bytes, "b" is bits and, accounting for overhead a 10x multiplier about right for simple calculations.

I think it's an 8X multiplier. There's 8 bits in a byte.

With The Birds · Oct 16, 2016

John Locke said:
I think it's an 8X multiplier. There's 8 bits in a byte.

Yes but we allow some overhead to account for brands that are a little on the optimistic side in their published specs. Not so much of an issue in recent times with cards being a lot faster generally.

Peter Galbavy · Oct 17, 2016

8 bits in a byte only works if you use synchronous packets with no delimiters, no start-of and no end-of etc. In a typical streaming protocol it is fair to *approximate* 10 bits to a byte. I speak from some years of exposure to this fun stuff.

RémyHeli · Oct 17, 2016

By the way, thumbs up to Peter's cat saying hello to us

Cool and relaxing.

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Peter Galbavy · Oct 17, 2016

RémyHeli said:
By the way, thumbs up to Peter's cat saying hello to us Cool and relaxing.

They are *almost* OK with the P4 - I make sure they are well clear if I ever do test flights in the garden, but the topcat (Dicky, NOT Leo who is the one in my Avatar) likes to bat at the P4 when it's prop-less and on a table indoors for maintenance

See about 30 seconds into my first test flight video
Dicky is the one nearest me (out of shot on the left) and again appears right near the end, still next to me. He is pretty fearless.

RémyHeli · Oct 19, 2016

Peter Galbavy said:
They are *almost* OK with the P4 - I make sure they are well clear if I ever do test flights in the garden, but the topcat (Dicky, NOT Leo who is the one in my Avatar) likes to bat at the P4 when it's prop-less and on a table indoors for maintenance

See about 30 seconds into my first test flight video

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Dicky is the one nearest me (out of shot on the left) and again appears right near the end, still next to me. He is pretty fearless.