PNX1502E Datasheet, PDF (653/819 Pages) NXP Semiconductors – Connected Media Processor

Philips Semiconductors
Volume 1 of 1
PNX15xx Series
Chapter 21: MPEG-1 and MPEG-2 Variable Length Decoder
Table 6: References for the MPEG-2 Macroblock Header Data …Continued
Item
Default Value References from MPEG-2 Video Standard, IS 13818-2 Document
MV Field Sel[0]0] to
MV Field Sel[1][1]
Undefined
Section 6.2.5 and 6.2.5.2
Motion Code[0][0][0] to Undefined
Motion Code[1][1][1]
Section 6.2.5.2.1 and Table B-10
Motion Residual[0][0][0] Undefined
to Motion
Residual[1][1][1]
Section 6.2.5.2.1; the corresponding rsize bits are extracted from the bitstream
and stored as left justified; to get the final value shift the given number by (8 -
corresponding rsize). The rsize values are stored in MP_VLD_PI register
Start Code
-
Copy of the internal start-code register; see Section 5. Register Descriptions.
dmvector[1] and
dmvector[0]
Undefined
Section 6.2.5.2.1 and Table B-11; signed 2-bit integer from Table B11.
CBP
-
Section 6.2.5, 6.2.5.3 and Table B-9
Quant Scale
-
Section 6.2.5; 5 bits from bitstream; use Table 7-6 to compute the quant scale
value.
MPEG-1 Parsing
For each MPEG-1 macroblock parsed by the VLD, four 32-bit words of macroblock
header information will be output from the VLD. Refer to Figure 1.
The fields described in Figure 3 may or may not be valid depending upon the MPEG-
1 video standard. See Table 7 for more details on the macroblock header data
31
25
17
11
6
4
Esc Count
MBA Inc
MB Type
First Forward Motion Vector
31 30
29
23
15
Motion Code [0][0][0] Motion Residual [0][0][0]
3
2
1
0
First MB
w0
13
7
Motion Code [0][0][1] Motion Residual [0][0][1] w1
First Backward Motion Vector
31 30
29
23
15
Motion Code [0][1][0] Motion Residual [0][1][0]
13
7
Motion Code [0][1][1] Motion Residual [0][1][1] _w2
31
23
16
14
12
10
4
slice_start_code
CBP
quant scale _w3
Shaded areas represent bits not implemented in the MPEG-1 specification.
These bits are written as zeros.
Figure 3: MPEG-1 Macro Block Header Output Format
12NC 9397 750 14321
Product data sheet
Rev. 2 — 1 December 2004
© Koninklijke Philips Electronics N.V. 2002-2003-2004. All rights reserved.
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