The Source Input Format(SIF) is a display format that uses MPEG-1. In the European version, the SIF display format has a resolution of 352 x 240 pixels and 25 Hzrefresh rate. This resolution corresponds to that of a video field.
In the PAL television standard, 575 of the 625 lines are visible as a full frame. In relation to a field, this results in a resolution of 288 vertical lines or pixels. Halving the horizontal resolution results in approximately the specified resolution of 360 pixels per line. With a color depth of 24 bits, this results in a data stream of 62.208 Mbit/s.
If the color information is transferred to the YUV color model and a color subsampling of 4:1:1 is used for the color difference signals, the data volume is reduced to that of the luminance signal with 360 x 288 x 25 Hz x 8 bits, i.e. to 20.736 Mbit/s, and that of the color difference signals to 180 x 144 x 25 x 8, i.e. 5.184 Mbit/s, which corresponds to the resolution of Quarter SIF( QSIF).