
Philips Semiconductors
PNX15xx Series
Volume 1 of 1
Chapter 21: MPEG-1 and MPEG-2 Variable Length Decoder
PNX15XX_SER_3
Koninklijke Philips Electronics N.V. 2006. All rights reserved.
Product data sheet
Rev. 3 — 17 March 2006
21-11
MPEG-2 Parsing
For each MPEG-2 macroblock parsed by the VLD, six 32 bit words of macroblock
header information will be output from the VLD. See
Figure 2.The elds described in
Figure 2 may or may not be valid depending upon the MPEG-
2 video standard. See
Table 6 for more details on the macroblock header data.
Figure 2:
MPEG-2 Macro Block Header Output Format
Esc Count
MBA Inc
MB Type
Mot Type DCT Type
MV count
MV Format
DMV
MV Field Sel [0][0]
Motion Code [0][0][1]
Motion Residual [0][0][0]
Motion Residual [0][0][1]
Motion Code [0][0][0]
MV Field Sel [1][0]
Motion Code [1][0][1]
Motion Residual [1][0][0]
Motion Residual [1][0][1]
Motion Code [1][0][0]
MV Field Sel [0][1]
Motion Code [0][1][1]
Motion Residual [0][1][0]
Motion Residual [0][1][1]
Motion Code [0][1][0]
MV Field Sel [1][1]
Motion Code [1]1][1]
Motion Residual [1][1][0]
Motion Residual [1][1][1]
Motion Code [1][1][0]
quant scale
CBP
dmvector[0]
dmvector[1]
31
First Forward Motion Vector
Second Forward Motion Vector (for MPEG-2 only)
First Backward Motion Vector
Second Backward Motion Vector (for MPEG-2 only)
0
1
2
3
4
6
11
17
25
7
15
23
29
30
31
13
7
15
23
29
30
31
13
7
15
23
29
30
31
13
7
15
23
29
30
31
13
4
10
12
14
31
w1
w2
w3
w4
w5
w0
MB2
First MB
slice_start_code
23
16
MB1
Table 6: References for the MPEG-2 Macroblock Header Data
Item
Default Value
References from MPEG-2 Video Standard, IS 13818-2 Document
Esc Count
0
Section 6.2.5
MBA Inc
-
Section 6.2.5 and Table B-1
MB Type
Undened
Section 6.2.5.1 and Tables B-2, B-3, and B-4; Only 5 Msb bits from the tables are
used
MotType
Undened
Section 6.2.5.1; Field or Frame motion type will be decided by the user
DCT Type
Undened
Section 6.2.5.1
MV Count
Undened
Tables 6-17 and 6-18. The MV Count value is one less than the value from the
tables.
MV Format
Undened
Tables 6-17 and 6-18
First MB
0
Set to ‘1’ for the rst macroblock of a slice
DMV
Undened
Tables 6-17 and 6-17