MicroSD card speed for 4K video

Sean Nelson wrote:

DMKAlex wrote:

Sean Nelson wrote:

DMKAlex wrote:

The speed seems to stabilize above 64KB read and write.

My video clips are usually 400,000 kb. How do I relate it to the ATTO result?

A good rule of thumb is to multiply bytes by 10 to get bits. It's actually 8, but it gives you a bit more conservative result and, more importantly, is easier! So 64K Bytes/sec ∼= 640K bits/sec.

Or if you want to be a bit more pedantic, 64K Bytes /sec × 8 bits/byte = 512K bits/sec.

Sean,

Your explanation is a bit above me.

I want to know if my video files are written in what block (the number in the y-axis)?

Ah, OK - so if I understand you correctly, the test results you posted show how fast the card is for various sizes of data transfers - very small transfers are slow but they are fast as long as the host is reading or writing around 64Kbytes or more at a time - and you're wondering whether the camera is writing data to the card using those larger transfers so as to maximize its speed.

I have no idea how to tell what transfer size the camera uses, but I'm pretty sure that it would be at least 64KBytes. If it wasn't, then the camera would have a hard time dumping data to the card fast enough.

Thanks, Sean.

I just want to make the cards can handle my kind of videoing, and so far it is doing OK. I refuse to pay for the more expensive cards. Got a Samsung EVO select 128gb as a spare for my upcoming trip. It's $17.50 delivered.