In 1992, the ISO MPEG committee published the MPEG-1 specification for compressed digital video as ISO 11172. This standard was designed to allow 74 minutes of digital video to be stored on a compact disc. The quality was superior to existing video formats . Philips, was one of the MPEG contributing companies, who adopted MPEG-1 for CD-i and later used for Video CD.  

The MPEG-1 digital video is intended for non-interlace displays, while MPEG-2 is for interlaced video display.  This means that a PAL or NTSC video signal will be encoded at SIF resolution, ie half the number of lines per video frame and half the pixels per line.

The diagram illustrates the sequence of frames in an MPEG-1 video. Note that the order they are displayed is different from the order in which they are read from the disc.

As Stored on Disk

As Displayed

Each of the macroblocks of a B-frame is coded as a change from the previous or next P-frame or I-frame. The I-frames are repeated at approximately 0.5 second intervals, otherwise the PBBPBB.. pattern is repeated indefinitely.

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