SAA7205 Philips Semiconductors, SAA7205 Datasheet - Page 18

• Manufacturer Part Number: SAA7205
• Description: MPEG-2 systems demultiplexer
• Manufacturer: Philips Semiconductors

Philips Semiconductors
7.5
The High Speed (HS) data filter module retrieves entire
transport packets, packet payloads, PES payloads, or
sections from the input stream, on the basis of a
programmable filter. The packets may contain data for
specific high speed data applications. In test mode
however, by reprogramming the filter
(word HS_pid12 to HS_pid0, address 0x0700;
see Table 13), data of other filters can be output. This
enables the user to monitor data streams directed to audio,
video, section data, and other filters. The HS data filter
features a programmable error handling mechanism. If the
‘HS_err_rmv’ (address 0x0701;see Table 13) bit is set,
erroneous output packets are removed from the stream.
If ‘HS_dupl_rmv’ (address 0x0701, see Table 13) is set,
the same is true for duplicate packets. Both removal
options can also be disabled.
In the single PID mode, the HS filter can be programmed
to operate in one of four filter modes (bits HS_mode,
address 0x0700, see Table 13), as indicated in Table 4.
Table 4 HS programmable filtering modes
1997 Jan 21
Single PID
mode
Single PID
mode
(continued)
Multiple PID
mode
OPERATING
MPEG-2 systems demultiplexer
MODE
High speed data interfacing
‘11..11’, indicating all PID
bits are relevant,
therefore only one
particular PID matches
‘11..11’, indicating all PID
bits are relevant,
therefore only one
particular PID matches
‘..0..1..’, indicating one or
more PID bits are don’t
care, so multiple PIDs
may match
(ADDRESS 0X0701;
see Table 13
PID MASK
total TS packet
TS packet
payload
PES packet
payload
section
total TS packet
FILTERING
OPTION
18
In multiple PID mode, only entire transport packets can be
output, for packets matching the PID specification.
Selected stream data is output (unbuffered) via the
GPO7 to GPO0 bus, at byte clock (DCLK) frequency
(rate = 9 MByte/s). Data is output in the format indicated in
Fig.8. The DCLK signal is a continuous byte clock.
The HSV signal is set for matching data only, otherwise it
is kept low. The HSSYNC signal indicates the position of
the first byte of the selected data, as indicated in Table 4.
Erroneous data is signalled by means of the HSE signal,
which is high for the duration of the erroneous packet.
In section mode HS data is selected on the basis of
table_id, and two section header bytes following the
section_length indicator (see Fig.26). For this purpose,
programmable filter masks are provided (address
0x0702 to 0x0704, see Table 13). If section mode is
selected, the general purpose output GPO7 to GPO0 does
not carry the full transport stream. Only selected sections
are output
outputs entire transport packets.
(HS_mode = 00,
address 0x0700, see Table 13)
outputs transport packet
payloads for a selected PID.
(HS_mode = 01)
output PES packet payloads for a
selected PID. (HS_mode = 10)
outputs entire sections, based on
PID, and table_id + 2 bytes
selection (addresses 0x0702 to
0x0704, see Table 13).
(HS_mode = 11 and
HS_sect_flt_en = 1)
output packet payloads only.
(HS_mode = 00)
FUNCTION
Preliminary specification
first byte of transport
packet
first byte of transport
packet payload, only
if payload_unit_
start_indicator is set
first byte of PES
packet payload
first byte of section
header
first byte of transport
packet
SAA7205H
HSSYNC