Source Input Format
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Source Input Format(SIF) defined inMPEG-1,is a video format that was developed to allow the storage and transmission ofdigital video.[1][2]
- 625/50SIF format (PAL/SECAM) has a resolution of352 × 288active pixels (half of PAL704 × 576) [or360 × 288active pixels (half of PAL720 × 576)] and arefresh rateof 25 frames per second.[2]
- 525/59.94SIF Format (NTSC) has a resolution of352 × 240active pixels (half of NTSC704 × 480) [or360 × 240active pixels (half of NTSC720 × 480)] and a refresh rate of 29.97 frames per second.[2]
When compared to theCCIR 601specifications, 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, andchrominance.SIF video is known as aconstrained parameters bitstream.[3]
Onsquare-pixeldisplays (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=4/3:352/288=12/11) and "reduced" horizontally by 10:11 for NTSC (PAR = DAR: SAR =4/3:352/240=10/11).
See also[edit]
References[edit]
- ^"Digital S Term Dictionary".JVC Professional.Retrieved2023-04-18.
- ^abcSetup of CCIR 601 multi-purpose coding system(PDF).PTT Research. 1991.
- ^"MPEG-1 VIDEO".Berkeley Multimedia Research Center.2009-04-12. Archived fromthe originalon 2009-04-12.Retrieved2023-04-18.