480-line Video

480 线视频 is a standard digital standard-definition format associated with the 525-line, approximately 59.94 Hz television system; the typical effective image resolution is 720×480. In analog systems, the total number of scan lines includes blanking and synchronization; digital file names are typically denoted by the number of effective vertical samples.

480i is typically transmitted at approximately 59.94 fields per second in interlaced mode, corresponding to approximately 29.97 full frame cycles; 480p, on the other hand, is progressive scan, commonly denoted as 59.94p. Cinematic 23.976p content can be downconverted to 480i via 3:2 pull-down; proper reverse processing can restore the original progressive frames, while standard deinterlacing may retain interlaced fields. NTSC is an analog color television standard, while 480i is a digital image format; although the two are often used interchangeably due to their historical connection, they are not the same concept. The 720×480 resolution in DVD-Video can be labeled as 4:3 or 16:9, depending on the display’s non-square pixel format; some formats use other horizontal resolutions such as 704×480 or 352×480.

480p is sometimes referred to as “enhanced definition” rather than “high definition.” It describes progressive scanning and vertical resolution but does not specify the codec, bitrate, or source quality. When an upscaling player outputs 1080p or 4K, the original program remains a 480-line source.