Source Input Format
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Source Input Format (SIF) defined in MPEG-1, is a video format that was developed to allow the storage and transmission of digital video.[1][2]
- 625/50 SIF format (PAL/SECAM) has a resolution of (360 or) 352 x 288 active pixels and a refresh rate of 25 frames per second.[2]
- 525/59.94 SIF Format (NTSC) has a resolution of (360 or) 352 x 240 active pixels and a refresh rate of 29.97 frames per second.[2]
When compared to the CCIR 601 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.[3]
SIF pixels are not square-pixels, instead having a pixel aspect ratio (PAR) of 12:11 (PAR = DAR : SAR = 4/3 : 352/288 = 12/11). So that the SIF image is not streched on computer screens, which normally consist of square-pixels, it must be displayed there on 320 x 240 square-pixels (QVGA, DAR = SAR = 4:3) for NTSC or on 384 × 288 square-pixels (DAR = SAR = 4:3) for PAL; with a refresh rate of whatever the computer is capable of supporting.
See also
References
- ^ "Digital S Term Dictionary". JVC Professional. Retrieved 2023-04-18.
- ^ a b c Setup of CCIR 601 multi-purpose coding system (PDF). PTT Research. 1991.
- ^ "MPEG-1 VIDEO". Berkeley Multimedia Research Center. 2009-04-12. Retrieved 2023-04-18.