Data volume and speed needs for two simultaneous 4K recordings on local storage

[Roadrunner007]

Just bought an Arlo Ultra 2 camera kit.

Planning on having both cloud and local storage active.

Also planning on having 1 Arlo Ultra wired and 1 Arlo Ultra on battery, both linked so that when one detects motion both start recording.

I am trying to decide what type of mircoSD card I need for the local storage.

Question 1: what speed should I select V30, V60 or V90 to support 2 simultaneous 4K recordings?

Question 2: what is the files size on the SD card of one 4K recording of e.g. 1 second. Trying to calculate how many hours of recording I get on a 64GB, 128GB or 256GB card respectively.

Thank you,  

[jguerdat · Accepted solution]

There are FAQs here that answer most questions like this. From https://kb.arlo.com/000062206/What-are-the-features-and-specifications-of-the-Arlo-Ultra-camera:

microSD card requirements	Speed class 10, UHS1, V10
Min home upload speed	2-4Mbps

One 40 second video on my camera is 9.6MB on best video. YMMV

[Roadrunner007]

Thank you for the response on data volume. If my math is correct a 64GB card will give me about 3 days of continuous recording. I think that should be plenty to cover a few months of incidents of 2 cameras.

Regarding speed requirements: I did see the microSD requirements in the FAQ. However it also said in an Arlo information that up to v90  UHS3 is supported. I am trying to understand if 2 simultaneous 4K reads would be covered by the minimum requirement "Speed class 10, UHS1, V10" or a higher speed would be required/recommended for this use scenario.

General information on speed requirements for camcorders states V30 as the minimum for one 4K stream. However, I assume the Arlo Ultra will produce a lot less data than regular camcorders and hence that general guidance is probably overstating the requirements.

Thank you,  

[jguerdat]

I can't be sure since I'm no expert but the overall bitrate of the 4k recordings isn't that high due to the compression/encoding used. Someone else with more knowledge may jump in here with real data but I wouldn't be concerned as long as the specs are met.

[StephenB]

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@Roadrunner007 wrote:

Thank you for the response on data volume. If my math is correct a 64GB card will give me about 3 days of continuous recording.

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Note CVR isn't recorded on the SD card at present.

Arlo says 3 megabits per second is the data rate requirement for the Ultra ( https://kb.arlo.com/000062043/What-are-the-minimum-requirements-for-installing-and-using-my-Arlo-sys... ) which definitely has some margin.

But taking the 3 megabits at face value, you'd get ~170K seconds of stprage on a 64 GB card.  64GB * 8000 -> 512000 megabits of data on the card.  Divide by 3, and you get 170,667 seconds (or about 2 days).

Arlo generally assumes 5 minutes/day for each camera for battery life estimates.  If that assumption holds for you, you'd have over 9 months retention on your 64 GB card.