SAA7201H/C1/S1 データシートの表示（PDF） - Philips Electronics
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SAA7201H/C1/S1 Datasheet PDF : 36 Pages
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Philips Semiconductors
Integrated MPEG2 AVG decoder
Objective specification
SAA7201
JTAG
The SAA7201 supports the standard Boundary Scan test
instructions: bypass, extest, sample, intest, runbist,
idcode.
Memory requirements
As indicated before the MPEG source decoder operates
with 16 Mbit of external memory. Several processes
require access to the external memory, mostly being the
video decoding process. In normal main level, main profile
video applications about 1.2 Mbit of memory space is free
for non-video processes. In practice most of this capacity
will be used for graphics. In combination with the internal
variable length decoding, full screen graphics at 8-bit per
pixel is feasible. Moreover, by having introduced a flexible
memory allocation procedure the available memory
capacity for graphics may be enlarged when decoding
lower resolution MPEG pictures or when the input bit rate
is less than 15 Mbit/s.
Obviously for graphics-only applications all 16 Mbit can be
used for the storage of bit-maps and look-up tables.
In Table 1 an overview is given of the required memory
capacity for some user defined modes.
In 50 Hz systems memory capacity can be saved by
restricting the chroma vertical interpolation to field
interpolation. This mode would only bring some extra
chroma resolution in case the input stream contains
progressive coded pictures.
In 60 Hz systems the reduction of storage capacity for
B-frames to field capacity has not only consequences for
the chroma vertical interpolation but also for the
3 : 2 pull-down operation mode. The operation
repeat-first-field is not possible in all cases and a modified
3 : 2 pull-down is performed under the control of the
SAA7201. The user may decide to use this modified
3 : 2 pull-down mode in order to have more memory
available for OSD or graphics.
Table 1 Required memory capacity for some user defined modes
System
50 Hz
60 Hz
Bit rate (R)
15 Mbit/s
15 Mbit/s
9 Mbit/s
Chroma interpolation
frame
field
field
frame
field
field
3 : 2 pull-down
n.a.
n.a.
n.a. full MPEG modified modified
Picture format
Audio input buffer
Video input buffer
Video implementation buffer (R/P)
Slave synchronization buffer (R/2P)
Reference and decoded picture
Total for video + audio
Remains for OSDG (224 = 16777 kbit)
720 × 576 720 × 576 544 × 576 720 × 480 720 × 480 720 × 480
64 kbit
64 kbit
64 kbit
64 kbit
64 kbit
64 kbit
1835 kbit 1835 kbit 1835 kbit 1835 kbit 1835 kbit 1835 kbit
600 kbit 600 kbit 400 kbit 500 kbit 500 kbit 300 kbit
300 kbit 300 kbit 200 kbit 250 kbit 250 kbit 150 kbit
13456 kbit 12719 kbit 9609 kbit 12441 kbit 10634 kbit 8042 kbit
16255 kbit 15518 kbit 12108 kbit 15090 kbit 13292 kbit 10391 kbit
522 kbit 1259 kbit 4669 kbit 1687 kbit 3485 kbit 6386 kbit
1997 Jan 29
20
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