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GDV 100 D/002
• General Description
The performance offered by the ST20 CPU and its associated hardware
(decoders, encoder, peripherals...) 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 decoder, PAL/NTSC encoder, ...),
- embedded peripherals drivers (UART, I
Smart Card, ...).
1. ST20 32-bit CPU
The STi5505 integrates a ST20 C2 core with the following
characteristics:
- 50K Dhrystones/s at 50MHz,
- 8/16 bits instructions (32 most common instructions in 8 bits),
- instruction cache 2Kbytes - write back replacement policy,
- internal SRAM 2Kbytes to ensure fast access to critical code, data,
interrupt handler ...
- data cache 2 Kbytes - write back replacement policy,
The CPU 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.
2. Video Decoder
The video decoder uses a patented memory reduction/bandwith
reduction scheme to offer the user the best bandwidth/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 memory usage is the normal three
buffers but the bandwith 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,
- memory reduction architecture allowing sharing of single 16 Mbits
SDRAM between MPEG decoding, 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.
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.
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
compatible 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 standard. The decoder can also handle linear PCM in
accordance with the DVD standard. An integrated down-sampler is
provided for conversion from 96 kHz to 48kHz.
The main features of the decoder core are:
- Decodes 5.1 Dolby AC-3 Digital surround,
- Output to 6 channels. Downmix modes: 1, 2, 3 or 4 channels for
MPEG and AC-3 streams,
- Karaoke mode for DVD. MPEG-2 capable, AC-3 capable,
- MPEG-1, 2-channel audio decoder layers 1 and 2,
- MPEG-2, 6-channel audio decoder layer 2,
- PCM: transparent. downsampling 96 to 48 kHz,
GRUNDIG Service
2
C, Programmable I/O,
- Accepts MPEG-2 PES stream format for: MPEG-2, MPEG-1, Dolby
AC-3 and Linear PCM,
- IEC6958 Output Interface,
- CD-DA PCM format (subcode output in IEC6958 user data),
- Downmix for Dolby Pro Logic compatible outputs for AC-3 and
MPEG-2 (Pro Logic encoder),
- Pro Logic decoder,
- PLL for Internal 44.1 and 48kHz PCM clock generation,
- On chip pink noise generator.
5. On-Screen Display
The display interface supports up to 256 colors for each OSD region
and a transparency feature allows mixing of video with the OSD. Fast
access graphics and many other additional features are available and
are supported by a graphics library. Very high system performance is
obtained by closely coupling the ST20 RISC processor and cache with
the MPEG audio/video core and display memory. Low latency RISC
access and DMA engines allow rapid construction of bit maps.
6. PAL/NTSC Encoder
The STi5505 integrates a PAL/NTSC encoder. It converts the digital
MPEG/Sub Picture/OSD stream into a standard analog baseband
PAL/NTSC signal and into RGB analog components. Six analog output
pins are available on which it is possible to output CVBS, S-VHS (Y/C)
and RGB formats.
The encoder handles interlaced and non-interlaced mode. It can
perform Closed Captions, CGMS or Teletext encoding and allows
Macrovision 7.01/6.1 copy protection. The encoder supports both
master and slave modes for synchronization.
7. Memory Interfaces
Two kinds of memory interfaces are used on the STi5505: a
programmable External Memory Interface (EMI) and a high performance
SDRAM interface. The External Memory Interface supports several
address ranges (memory banks). In each bank, a set of signals are
entirely programmable and can be used to map 8/16 bits peripherals
such as Front End channel ICs in DVD applications. The EMI contains
a zero glue logic DRAM and a low-cost EPROM interface. This
interface can be programmed to interface very easily peripherals. The
SDRAM memory interface supports gluelessly 125 MHz SDRAMs
providing the adequate bandwiths to achieve MPEG decoding and
display, OSD drawing and display, and general system use. Memory
savings can be realized on ROM requirements too: the ST20 VL-RISC
microcore has the highest code density of any 32 bit CPU, leading to
the lowest cost program ROM.
8. Front-End Interface
The front end interface accepts:
- DVD, VCD and CD-DA sectors,
- DVB-DSS transport stream.
In DVD mode, DVD, VCD and CD-DA information can be input into
STi5505 through a serial interface or a generic parallel interface. In
serial mode, data are captured and filtered from I
by an internal sector processor. V4 interface is used to capture VCD
and CD-DA subcode information. In parallel mode, sector processor is
bypassed.
The main features of the DVD interface are:
- DVD, VCD and CD-DA compatible,
- hardware sector filtering,
- subcode error correction for CD-DA,
- integrated CSS decryption,
- integrated track buffer support,
- DMA engine to ST20 memory.
In DVB-DSS mode, DVB-DSS transport stream is input through a
serial interface. The STi5505 extracts and descrambles Packet
Elementary Streams belonging to one user selected program to be
decoded and presented.
The main features of the DVB-DSS interface are:
- descrambling (transport packet and packet elementary streams in
DVB mode, transport packet in DSS mode ; up to 32 streams
descrambling),
- PID and section filtering,
- clock recovery,
- DMA engine.
In DVB-DSS mode, a high speed digital interface allows to transfer
packets between the Set Top Box and external units, either for
recording or playback purposes. This interface provides also full
support for an external IEEE1394 connection.
Description
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S and V4 interfaces
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