Below is useful information about SD cards and Consumption Rates:
SD Speed Class Rating (*)
The SD Association
defines standard speed classes indicating minimum performance to record
video. Both read and write speeds must exceed the specified value. These
are defined in terms of suitability for different applications:
- Class 2 for SD video recording
- Class 4 and 6 for HD ~ Full HD video recording,
- Class 10 for Full HD video recording and HD still consecutive recording
- UHS Speed Class 1 for real-time broadcasts and large-size HD videos
The specification defines these classes in terms of performance curves which translate into the following minimum performance levels, for both read and write, on an empty card:[40]
| Class |
Minimum performance |
| Class 2 |
2 M/sec |
| Class 4 |
4 MB/sec |
| Class 6 |
6 MB/sec |
| Class 10 |
10 MB/sec |
Speed Classes 2, 4, and 6 assert that the card supports the respective number
of MB/sec as a minimum sustained write speed for a card in a fragmented state.
Class 10 asserts that the card supports 10 MB/s as a minimum non-fragmented
sequential write speed.
By comparison, the older "×" rating measured maximum speed under ideal conditions,
and was vague as to whether this was read speed or write speed.
The host device can read a card's speed class, unlike the earlier "×" speed
ratings. A device can warn the user if the card reports a speed class that
falls below an application's minimum need.
* - SD card speed information courtesy of Wikipedia
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