Standard Definition
Standard Definition (SD) refers to a class of resolution used in video display and broadcasting. It represents a lower resolution compared to High Definition (HD), Full HD, and Ultra HD resolutions. The most common resolutions classified under Standard Definition are 480i and 576i, where the ‘i’ stands for interlaced scanning. In interlaced scanning, the image is displayed by alternating between showing the odd and even lines of pixels, which effectively halves the amount of data transmitted at any given moment. There are also progressive scan versions, denoted as 480p and 576p, where ‘p’ stands for progressive scanning, displaying all lines of the image in sequence.
In terms of aspect ratio, SD content typically comes in 4:3, which is more of a square shape, although it’s not uncommon to find 16:9 aspect ratio in SD content as well. Standard Definition was the dominant format for television broadcasts and home video for several decades before being gradually supplanted by high-definition formats in the 2000s and 2010s.
Despite the rise of higher-resolution formats, SD content is still in use, particularly in regions with limited bandwidth infrastructure, or for specific applications where high resolution is not a priority. For instance, some broadcast channels, DVDs, and older video content are still in SD. Also, in professional video production, SD resolutions are sometimes used for specific creative or practical reasons. Even though it doesn’t offer the clarity and detail of HD and beyond, Standard Definition played a pivotal role in the evolution of video technology and remains relevant in various contexts today.
Links
- Wikipedia: https://en.wikipedia.org/wiki/Standard-definition_television
- BoxCast: https://www.boxcast.com/blog/sd-vs-hd-vs-4k-live-streaming-resolutions-explained
- WeVideo: https://www.wevideo.com/blog/sd-vs-hd