Definitions
HD Video
High-definition video (HD Video) refers to videos of higher quality and resolution than standard-definition video. This involves display resolutions of 1,280 x 720 pixels x 30fps for 720p HD Video. Video support may vary based on host device, file attributes and other factors.
Full HD Video
Full high-definition video (Full HD video) refers to videos of an even higher quality and resolution than HD video. This involves a display resolution of 1,920 x 1,080 pixels x 30fps for 1080p Full HD Video. Video support may vary based on host device, file attributes and other factors.
4K/4K Ultra HD Video
4K resolution is a generic term for display devices or content having horizontal resolution on the order of 4,000 pixels. Several 4K resolutions exist in the fields of digital television and digital cinematography. In the movie projection industry, Digital Cinema Initiatives (DCI) is the dominant 4K standard. Video support may vary based on host device, file attributes and other factors.
Ultra High Definition (UHD) is an umbrella term that encompasses higher resolutions (more pixels) than HDTV, as well as more realistic color and higher frame rates.
When used in a home context, 4K/UHD means the TV's screen has a minimum resolution of 3,840 pixels wide and 2,160 pixels high, making it the equivalent of two 1080p screens in height and two in length. This resolution was originally known as Quad HD.
Another resolution, known as 4K x 2K (4,096 x 2,160 pixels), is used by some projectors and many professional cameras. It also falls under the umbrella of 4K/UHD.
With the arrival of 4K, there are four main resolution standards for use in the home: standard definition (480p/540p), high definition (720p), full high definition (1080p) and ultra-high definition (2160p).
Video Speed Class
There are two kinds of video speed classifications: Speed Class and UHS Speed Class. These indicate the minimum sustained write speed necessary for video recording, so that minimum and constant speed is guaranteed for camcorders and cameras. Speed Class is designated as Class 2, 4, 6 and 10, and UHS Speed Class is designated UHS Speed Class 1 or UHS Speed Class 3.
Higher class rated cards support high bit-rates of video and higher quality video recording. SanDisk Class 4 memory cards are ideal for HD video capture, and Class 10, UHS Speed Class 1 and UHS Speed Class 3 memory cards support Full HD and 4K Ultra HD video capture. Check your camera/camcorder for the recommended class rating.
For CompactFlash cards, look for Video Performance Guarantee (VPG). VPG-20 means Video Performance Guarantee enabled to ensure video recording at 20MB/s minimum sustained write speed. VPG-65 is Video Performance Guarantee enabled to ensure video recording at 65MB/s minimum sustained write speed. Performance may be lower depending on host device. 1MB=1,000,000 bytes.
Speed Class Ratings1
| Class 2 |
Standard video |
| Class 4 |
HD Video |
| Class 6 |
Full HD Video |
| Class 10 |
Full HD Video |
| UHS Speed Class 1 (U1) |
Full HD Video. Supports real time video recording. |
| UHS Speed Class 3 (U3) |
Full HD and 4K Video. Supports real time video recording. |
UHS-I
UHS stands for Ultra High Speed. SDHC and SDXC products that are UHS-I enabled offer bus-interface speeds, capable of supporting theoretical data transfer speeds of up to 104MB/s, four times faster than the previous possible transfer speed of 25MB/s. (UHS enabled host device required to realize the higher performance.) Cards supporting UHS-I are fully backwards-compatible in non-UHS hosts, although performance in non-UHS hosts will be limited by the host's bus-interface capability.
UHS-II
UHS-ll is the latest and fastest SD card interface available to communicate to camera/camcorder hosts and to computers with maximum bus interface speeds up to 312MB/s. Cards supporting UHS-ll are fully backwards-compatible in UHS-l hosts, although performance in UHS-l hosts will be limited by the host's bus-interface capability.
Normal and high-speed cards can also be used with UHS-I host devices. Higher performance enabled by a UHS-II host device can only be achieved with a UHS-II memory card.
