Common Intermediate Format

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CIF (Common Intermediate Format or Common Interchange Format), also known as FCIF (Full Common Intermediate Format), is a standardized format for the picture resolution, frame rate, color space, and color subsampling of digital video sequences used in video teleconferencing systems. It was first defined in the H.261 standard in 1988.

As the word "common" in its name implies, CIF was designed as a common compromise format to be relatively easy to convert for use either with PAL or NTSC standard displays and cameras. CIF defines a video sequence with a resolution of 352 × 288, which has a simple relationship to the PAL picture size, but with a frame rate of 30000/1001 (roughly 29.97) frames per second like NTSC, with color encoded using a YCbCr representation with 4:2:0 color sampling. It was designed as a compromise between PAL and NTSC schemes, since it uses a picture size that corresponds most easily to PAL, but uses the frame rate of NTSC. The compromise was established as a way to reach international agreement so that video conferencing systems in different countries could communicate with each other without needing two separate modes for displaying the received video.