MPEG2

MPEG2 [ISO93] was developed to efficiently encode television sequences, or CCIR601 video. It supports various combinations of input formats and bitrates, with the three main formats as in Table 2.1. As a superset of MPEG1, it provides backwards compatibility, but it is targeted at applications well above 2 Mbps.

 

Table 2.1: MPEG2 main bit rates and applications.

Application	Input video	Coded bitrate
Home entertainment video	$352 \times 240$, 30fps	1.5 Mbps
Digital television	$720 \times 486$, 30fps	5-10 Mbps
Extended definition TV	$1920 \times 1080$, 30fps	30-40 Mbps

 

While MPEG2 is largely based on the MPEG1 encoding techniques, it specifies a number of enhancements, including:

• Support of interlaced video in addition to progressively scanned video.
• More chrominance sampling modes, including 4:2:2 and 4:4:4.
• Support of scalable video coding, implementing spatial, temporal, SNR and data partitioning scalability, which are described in later chapters.

MPEG2 does not prescribe these capabilities to the encoder, but allows the selection of some or all of them, through combinations of profiles and levels. This provides the very desirable flexibility that MPEG1 lacked, and broadens the range of potential applications for MPEG2.

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