Quick benchmark of a few SD cards I use for video recording
I've accumulated a few Micro SDHC memory cards for filming with GoPro Hero 4 Black and a Panasonic HC-V750, and thought I'd do a quick benchmark to see how they stack up relative to marketing claims and prices.
All but one of the cards below claimed UHS Speed Class rating of 3, according to the little "U3" symbol on them. Only the Sony was U1.
|SANDISK||SDSDQXN-032G-G46A||U3||51.9 MB/s||23.6 MB/s||0.83 ms||$25.17||2015-01-24|
|SANDISK||SDSDQX-032G-AFFP-A||U3||39.6 MB/s||22.4 MB/s||1.11 ms||$33.78||2015-01-24|
|SANDISK||SDSDQXN-032G-G46A||U3||48.0 MB/s||19.2 MB/s||0.84 ms||$27.20||2015-04-05|
|LEXAR||LSDMI32GBBNL633R||U3||54.3 MB/s||16.2 MB/s||0.87 ms||$23.95||2015-10-04|
|SONY||SR32UXA/TQ||U1||51.1 MB/s||13.7 MB/s||1.14 ms||$18.35||2015-09-25|
|PNY||P-SDU32GU390G-GE||U3||56.6 MB/s||13.6 MB/s||0.89 ms||$15.99||2015-09-25|
Lies, and damned lies
All of them fell short of the U3 specification, which, according to the SD Association Speed Class standard, means a minimum of 30 MB/s write.
All of them exceeded the U1 spec of 10 MB/s, which, according to the SD Association, is the minimum for 1080p (Full HD) video recording. On both the GoPro and the Panasonic, I usually record at 1080p120.
Extreme Plus what?
One of the two SanDisk Extreme cards (SDSDQXN-032G-G46A) I have, actually outperformed the more expensive SanDisk Extreme Plus (SDSDQX-032G-AFFP-A) -- so I won't be paying a premium for "Extreme Plus" again.
What's GoPro thinking?
GoPro doesn't publish speed requirements, but lists specific card recommendations.
The Lexar LSDMI32GBBNL633R is listed among them as of this writing. The one I have writes at around 16.2 MB/s -- almost half of 30 MB/s listed as the recommended minimum for 4K video recording by the SD Association.
Presumably, GoPro did some testing to recommend this card for the Hero 4 Black, which can record at 4K. If so, then all of the cards I have should be fine for 1080p, including the PNY that is half the price of the SanDisk.
All these cards also meet Panasonic requirements, whose Owner's Manual calls for Class 10 (also 10MB/s, same as U1), when using the FULL HD Slow Motion Video Mode.
Benchmark, system, and hardware info
Recording one video at a time is a sequential write, and playback (or copying videos off the card) is a sequential read, so those are the benchmarks I'm mainly interested in.
Since these are simple benchmarks, I used a simple utility: gnome-disks from the gnome-disk-utility package (version 3.10.0-1ubuntu3). Since I have other things to do, kept sample size to 100 MiB. 10 samples for read/write tests, 1000 for access time.
All cards were partitioned by GoPro (FAT32 filesystem).
Card reader: Anker USB 3.0 (68ANREADER-B2A)
Motherboard: ASUS SABERTOOTH 990FX