Yet Another Cycling Forum

Random Musings => Gallery => Phototalk => Topic started by: Martin109 on 31 December, 2019, 01:29:05 pm

Title: Which Micro SD Card for 4k Camera
Post by: Martin109 on 31 December, 2019, 01:29:05 pm
I've been given one of these (https://www.aldi.co.uk/action-camera/p/700972317715600) for Christmas, and I need to get a microSD card for it.  What size card would manage 1 hour's worth of video at the highest resolution?
Title: Re: Which Micro SD Card for 4k Camera
Post by: jdsnape on 31 December, 2019, 02:01:56 pm
It should say in the manual ideally :)

The key thing is how fast the card can be written to - I'm not sure what this camera needs, but Sony recommends U3 for theirs. I can see someone in the comments on the Aldi page is getting a class 10 (slightly slower than U3) . There's a chart on the wikipedia page here: https://en.wikipedia.org/wiki/SD_card#Comparison_3
Title: Re: Which Micro SD Card for 4k Camera
Post by: Martin109 on 31 December, 2019, 02:11:00 pm
Thanks.  The manual only states: "Ensure that the microSD card you have inserted has a maximum capacity no more than 128GB and is at least Class 10."  It doesn't say anything about how long videos at different resolutions would last.  It states: Image resolution 16MP.  Video resolution: 4K 60/30FPS, 1080P 120/60/30FPS, 720P 240/120/60/30FPS
Title: Re: Which Micro SD Card for 4k Camera
Post by: Martin109 on 31 December, 2019, 02:18:24 pm
Your helpful Wikipedia article states: SD Cards will read and write at speeds of 12.5 MBs.  Would that then mean that recoding to it at that rate for one hour would store 12.5 x 60 x 60 = 45000Mb = 45Gb?
Title: Re: Which Micro SD Card for 4k Camera
Post by: Wobbly John on 31 December, 2019, 02:23:50 pm
Look for cards with a high 'V' number - 60 or 90.

(https://assets.hardwarezone.com/img/2017/12/st_20170705_vcsd055_3252281.jpg)

For video on the move, I find 60fps is preferable to high res 30fps.

Last year's Aldi camera came with a 4Gb card but were lower res. Our local store reduced the price of theirs a few weeks into the new year, and I bought a couple at £4.99 each!  :smug:
Title: Re: Which Micro SD Card for 4k Camera
Post by: Martin109 on 31 December, 2019, 02:36:12 pm
Thanks, WJ.

So, is my numpty calculation of 30Mb/s x 60 x 60 correct to give 108,000Mb (= 108 Gb) for an hour's recording?
Title: Re: Which Micro SD Card for 4k Camera
Post by: Martin109 on 31 December, 2019, 02:38:06 pm
Sorry, your recommendation was v60, so:

60Mb/s x 60 x 60 gives 216,000Mb (= 216 Gb) for an hour's recording.  That would exceed their max capacity limit of 128Gb.
Title: Re: Which Micro SD Card for 4k Camera
Post by: jdsnape on 31 December, 2019, 02:40:23 pm
Sorry, your recommendation was v60, so:

60Mb/s x 60 x 60 gives 216,000Mb (= 216 Gb) for an hour's recording.  That would exceed their max capacity limit of 128Gb.

That would be if the camera were writing to the card at it's full rate continuously. The card needs to be fast enough to support the fastest rate the camera might need to write to it. Given what your manual says, I'd probably make sure I went for a class 10 (10Mbps max) if I was going to shoot at 1080p or below, or a U3 (30Mbps max) if I was going to shoot 4K.

It's a bit tricky to work out how much space videos of different resolutions will take up, as it depends on the encoding they're using and what compression. Is there any info in the manual on that? As a rough guide though, if you're recording 1080p at 60fps I *think* you'd be looking at up to 100GB / hour. Obviously, if you shoot at a lower resolution (e.g. 720P) or framerate (e.g. 30fps) it'd take up correspondingly less space. 
Title: Re: Which Micro SD Card for 4k Camera
Post by: Martin109 on 31 December, 2019, 02:48:20 pm
Thanks, but no information on encoding or compression.