576p

576p is the shorthand name for a video display resolution. The p stands for progressive scan, i.e. non-interlaced, the 576 for a vertical resolution of 576 pixels, usually with a horizontal resolution of 768 or 720, depending of the relationship aspect. The 576p quality was decided as the default quality when converting from VHS to digital. 576p is SD quality, but it can be considered HD if the video bitrate number (kbit/s) is 8128 or higher. The frame rate can be given explicitly after the letter.[1]

Resolution Pixels

16:9 576p= 1024x576

4:3 576p= 768x576

3:2 576p= 864x576

Lines scanning

i: Interlaced scan 576i p: Progressive scan 576p. Only on PAL or SECAM

576p25

576p25 has a frame rate of 25 frames per second, and thus uses the same bandwidth and carries the same amount of pixel data as 576i; as such, 576p25 is considered to be standard definition. It can be used on analog PAL or SECAM systems, where it may be transported as a 576i signal with both interlaced fields corresponding to a unique frame. PALplus supports it via a "movie" mode signal flag. It can also be transported by both major digital television formats, ATSC and DVB, and on DVD.

576p50

With doubled temporal resolution, 576p50 is considered enhanced-definition television (EDTV), regardless of the image being scaled the same way as an interlaced frame. In some countries, such as Australia, the 576p resolution standard is technically considered high-definition and was in use by the Special Broadcasting Service (SBS TV) (16:9 the format has aspect ratio 1.468), eventually replaced by 720p for its high-definition subchannel; SBS later changed to using 1080i. The Seven Network initially used 576p for its high-definition subchannel, but now uses 1080i instead.

The frames are doubled (from a 25 frame source) on broadcast (to avoid flicker) for display devices that lack any kind of frame doubling ability. Widescreen 16:9 material has only the width scaled down to fit 720 pixels instead of an unscaled 1024 width. SMPTE 344M defines a 576p50 standard with twice the data rate of BT.601, using 704 × 576 active pixels with 16 x 576 horizontal blanking pixels.

See also

Television

References
  1. AfterDawn.com. "576p - AfterDawn: Glossary of technology terms & acronyms".
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