Philips DVDR1000/001 Service Manual page 231

Circuit-, IC Descriptions and List of Abbreviations
I - GENERAL DESCRIPTION
The performance offered by the ST20 CPU and its
associated hardware (decoders, encoder, periphe-
rals...) allows an integrated and unified DVD or
DVD-DVB software solution.
All the following operations are performed inside
the STi5505 :
- application management (DVD Navigation, VCD,
CD-DA, DVB-Program Guide ...),
- device data retrieval drivers (demultiplex, stream
buffer management ...),
- device presentation drivers (video decoder, sub-
picture decoder, on-screen display, audio de-
coder, PAL/NTSC encoder ...),
- embedded peripherals drivers (UART, I
grammable I/O, Smart Card ...).
I.1 - ST20 32-bit CPU
The ST20 micro-core family has been developped
by SGS-THOMSON Microelectronics to provide
the tools and building blocks to enable the devel-
opment of highly integrated application-specific 32-
bits device at the lowest cost and fastest time to
market.
The STi5505 integrates a ST20 C2 core with the
following characteristics :
- 50K Dhrystones/s at 50MHz,
- 8/16 bits instructions (32 most common instruc-
tions in 8 bits),
- instruction cache 2Kbytes - write back replace-
ment policy,
- internal SRAM 2Kbytes to ensure fast access to
critical code, data, interrupt handler ...
- data cache 2 Kbytes - write back replacement policy,
The STi5505's ST20 is provided with advanced
debugging tools :
- on-chip real-time emulation,
- debugging with minimal impact on software and
performance,
- non intrusive attachment to the host via JTAG
(IEEE1149.1),
- no intrusion into the performance of the CPU core,
- no intrusion into user code space by a debug kernel,
- only 40bytes used for breakpoint handler.
I.2 - Video Decoder
The video decoder implemented in the STi5505
uses a patented memory reduction/bandwith re-
duction scheme to offer the user the best band-
width/memory size compromise.
The algorithm is lossless and uses "on-the-fly"
decoding to reduce the memory requirements to
two frame buffers in memory reduction mode.
In this mode, PAL decoding is contained in 12Mbits.
When used in bandwith reduction mode, the mem-
ory usage is the normal three buffers but the band-
with required by the decoder is significantly
reduced compared to a classical implementation.
In summary, the features of the decoder are :
- MPEG-2 Main Profile/Main Level (MP@ML) support,
- MPEG-2 program streams, Packet Elementary
streams and MPEG-1 system streams support,
2
C, Pro-
- memory reduction architecture allowing sharing
of single 16 Mbits SDRAM between MPEG de-
coding, micro and transport functions - memory
expandable to 32 Mbits of SDRAM,
- letter box (16:9) filter,
- pan-scan, horizontal and vertical image resizing,
- automatic error concealment.
I.3 - Subpicture Decoder
The STi5505 has a hardware DVD compliant sub-
picture decoder. Subpicture units are copied by
DMA into subpicture bit buffer.
The subpicture decoder can decode complete sub-
picture units without any interaction from the ST20.
The main subpicture decoder features are :
- up to 720x480 or 720x576 subpicture area,
- internal LUTs for Sub Picture, Highlight and PCI
(4 bits color and contrast outputs),
- internal color LUT (4 bits from SP, HL, PCI to 24 Y,Cr,Cb
bits) for SP color inputs to MPEG, OSD, SP mixer.
I.4 - Audio Decoder
The audio decoder cell is a fully compatible Dolby
AC-3 / MPEG-1/MPEG-2 decoder capable of
decoding both 5.1 and 2 channel streams compat-
ible with the DVD standard.
Downmix from 5.1 channels is supported for both
Dolby and MPEG-2 streams. The output can be
sent directly to external DACs or formatted for
transmission in accordance with the IE6958 stand-
ard.
The decoder can also handle linear PCM in accord-
ance with the DVD standard. An integrated down-
sampler is provided for conversion from 96 kHz to
48kHz.
DVDR1000 /0x1 /691
STi5505 (Rev. Ax)
9. GB 231