Source Input Format (SIF) defined in

MPEG-1 MPEG-1 is a Technical standard, standard for lossy compression of video and Audio frequency, audio. It is designed to compress VHS-quality raw digital video and CD audio down to about 1.5 Mbit/s (26:1 and 6:1 compression ratios respectively ...

, is a video format that was developed to allow the storage and transmission of

digital video Digital video is an electronic representation of moving visual images (video) in the form of encoded digital data. This is in contrast to analog video, which represents moving visual images in the form of analog signals. Digital video comprises ...

. * 625/50 SIF format (

PAL Phase Alternating Line (PAL) is a color encoding system for analog television. It was one of three major analogue colour television standards, the others being NTSC and SECAM. In most countries it was broadcast at 625 lines, 50 fields (25 ...

SECAM SECAM, also written SÉCAM (, ''Séquentiel de couleur à mémoire'', French for ''sequential colour memory''), is an analog color television system that was used in France, Russia and some other countries or territories of Europe and Africa. ...

) has a resolution of active pixels (half of PAL ) [or active pixels (half of PAL )] and a

refresh rate The refresh rate, also known as vertical refresh rate, vertical scan rate or vertical frequency in reference to terminology originating with the cathode-ray tubes (CRTs), is the number of times per second that a raster-based display device displa ...

of 25 frames per second. * 525/59.94 SIF Format (

NTSC NTSC (from National Television System Committee) is the first American standard for analog television, published and adopted in 1941. In 1961, it was assigned the designation System M. It is also known as EIA standard 170. In 1953, a second ...

) has a resolution of active pixels (half of NTSC ) [or active pixels (half of NTSC )] and a refresh rate of 29.97 frames per second. When compared to the

CCIR 601 ITU-R Recommendation BT.601, more commonly known by the abbreviations Rec. 601 or BT.601 (or its former name CCIR 601), is a standard originally issued in 1982 by the Comité consultatif international pour la radio, CCIR (an organizati ...

specifications, which defines the appropriate parameters for digital encoding of TV signals, SIF can be seen as being reduced by half in all of height, width, frame-rate, and chrominance. SIF video is known as a constrained parameters bitstream. On square-pixel displays (e.g., computer screens and many modern televisions) SIF images should be rescaled so that the picture covers a 4:3 area, in order to avoid a "stretched" look. So the computer industry has defined "square-pixel SIF" to be 320 x 240 active pixels ( QVGA) or 384 x 288 active pixels, with a refresh rate of whatever the computer is capable of supporting. To reach that the SIF content need to be "expanded" horizontally by 12:11 for PAL ( PAR = DAR : SAR = : = ) and "reduced" horizontally by 10:11 for NTSC (PAR = DAR : SAR = : = ).

References

Graphics standards MPEG {{tv-tech-stub

See also

References