DigitalVideoAndHDTVAlgorithmsAndInterfaces.pdf

Table 40.7 MPEG
macroblock types Prediction
Typ. quantizer
matrix
Intra None – the macroblock is self-contained Perceptual
Nonintra
Backward
predictive-coded
Forward
predictive-coded
Bidirectionally
predictive-coded
Table 40.8 MPEG
picture coding types
Binary
code
I-picture 001 Yes Intra
Predicts from a future anchor picture Flat
Predicts from a past anchor picture Flat
Averages predictions from past and future
anchor pictures
Anchor
picture? Permitted macroblock types
P-picture 010 Yes Intra
Forward predictive-coded
B-picture 011 No Intra
Forward predictive-coded
Backward predictive-coded
Bidirectionally predictive-coded
Table 40.9 MPEG-2
prediction modes
Max. MVs
for Description back. fwd.
Frame prediction (P, B)-frames Predictions are made for the frame, using
data from one or two previously
reconstructed frames.
Field prediction (P, B)-frames,
(P, B)-fields
16×8 motion
compensation
(16×8 MC)
Dual prime P-fields with
no intervening
B-pictures
Dual prime P-frames with
no intervening
B-pictures
Predictions are made independently for
each field, using data from one or two
previously reconstructed fields.
(P, B)-fields The upper 16×8 and lower 16×8 regions
of the macroblock are predicted separately.
(This is completely unrelated to top and
bottom fields.)
CHAPTER 40 MPEG-2 VIDEO COMPRESSION 483
Flat
Two motion vectors are derived from the
transmitted vector and a small differential
motion vector (DMV, -1, 0, or +1); these
are used to form predictions from two
anchor fields (one top, one bottom), which
are averaged to form the predictor.
As in dual prime for P-fields (above), but
repeated for 2 fields; 4 predictions are
made and averaged.
1 1
1 1
2 2
1 1
1 1