Common Intermediate Format

CIF (Common Intermediate Format) is used to standardize the horizontal and vertical resolutions in pixels of YCbCr sequences in video signals. It was designed to be easy to convert to PAL or NTSC standards. It was first proposed in the H.261 standard. It defines a video sequence with a resolution of 352×288, a frame rate of 30000/1001 (roughly 29.97) fps, with color encoded using YCbCr 4:2:0.
QCIF means "Quarter CIF". To have one fourth of the area as "quarter" implies, height and width of the frame are halved.
Terms also used are SQCIF (Sub Quarter CIF), 4CIF (4× CIF) and 16CIF (16× CIF). The resolutions for all of these formats are summarized in the table below.

Format:	Video Resolution:
SQCIF	128 × 96
QCIF	176 × 144
CIF	352 × 288
4CIF	704 × 576
16CIF	1408 × 1152

All xCIF formats result in an image of aspect ratio 4:3; hence the xCIF pixels are NOT square! On a computer screen (with square pixels) xCIF pictures have to be stretched for a resulting aspect ratio of 4:3. To correctly display CIF content on a computer screen, the CIF content must be stretched horizontally by ~9% to 384 x 288.

 

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Common Intermediate Format".