576i

576i is a standard-definition video format used in regions that historically adopted the PAL and SECAM television systems. The 576 refers to the number of horizontal lines in each interlaced frame, and the i indicates interlaced scanning. In this system, there are 50 fields per second (two fields make one frame), so the frame rate is 25 frames per second. Each frame comprises two interlaced fields, resulting in 576 active video lines per frame and 625 total lines per frame when including nonvisible lines.

In digital representations, 576i is commonly mapped to a resolution of 720x576, with aspect ratios that can be 4:3 or 16:9 (the 16:9 version is typically stored anamorphically). The format is part of the PAL/SECAM broadcast family and has long been used for standard-definition television, DVDs, and various SD video services in PAL regions. It is widely carried by DVB-based services, among others. In contrast, North American broadcasting and many modern formats favor 480i, 720p, or 1080i/1080p under ATSC or similar standards.

Color encoding originally follows the PAL system in analog transmissions, with digital implementations often described using ITU-R BT.601 sampling when converted or stored. 576i remains a common SD option for compatibility with legacy equipment and regional broadcasting while newer systems increasingly prefer higher resolutions and progressive scanning.