A source picture is a contiguous rectangular array of pixels. A picture may be a complete frame of video ("frame picture") or one of the interlaced fields from an interlaced source ("field picture").
A field picture does not have any blank lines between its active lines of pixels. If viewed on a normal display it would appear "short and fat".
A coded picture (also called a video access unit) begins with a start code and a header.
The header carries -
As stated above, a picture may be a frame picture or a field picture.
A frame picture consists of:
a frame of a progressive source or
a frame (2 spatially interlaced fields) of an interlaced source
A field picture consists of only one field from an interlaced source.
In a progressive sequence, all pictures are frame pictures, and all macroblocks are frame DCT coded.
In an interlaced sequence, any frame may be coded as a frame picture or as two field pictures. In a frame picture from an interlaced sequence, individual macroblocks may be either field DCT coded or frame DCT coded. In a field picture, all macroblocks are field coded by default since all pixels are from only one field.
- Field DCT Coding and Frame DCT Coding
- GROUP of PICTURES (GOP)
- PACKETIZED ELEMENTARY STREAM
Up to MPEG 2 Video Data Structures