Which ratio is standard for Standard Definition video content?

Standard Definition (SD) video content is typically represented using a 4:3 aspect ratio. This ratio corresponds to the traditional television format that was prominent prior to the widescreen formats becoming standard. The 4:3 ratio means that for every four units of width, there are three units of height. This aspect ratio is well-established in the broadcasting and film industries, particularly for older television sets and media.

The other aspect ratios listed are associated with different video formats. The 16:9 ratio is standard for High Definition (HD) and widescreen formats, while the 2:1 ratio is often used in cinema for movies that aim to provide a more immersive experience. A 1:1 ratio is typically used in social media platforms and for certain types of digital media where a square format is preferred. Therefore, the 4:3 aspect ratio stands out as standard specifically for Standard Definition video content.