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EN 230
9.
DVDR980-985 /0X1
STi5508
1.4
Audio decoder
The audio decoder accepts: Dolby Digital, MPEG-1 layers I and II, MPEG-2 layer II 6-channel, PCM, CDDA data
formats; MPEG2 PES streams for MPEG-2, MPEG-1, Dolby Digital, MP3, and Linear PCM (LPCM). The audio decoder
supports DTS digital out (DVD DTS and CDDA DTS).
S/PDIF input data (IEC-60958 or IEC-61937 standards) is accepted if an external circuitry extracts the PCM clock from
the stream.
Skip frame, repeat blocks and soft mute frame features can be used to synchronize audio and video data. PTS audio
extraction is also supported.
The device outputs up to 6 channels of PCM data and appropriate clocks for external digital-to-analog converters.
Programmable downmix enables 1,2,3 or 4 channel outputs. Data can be output in either I²S format or Sony format. The
decoder can format output data according to IEC-60958 standard (for non compressed data: L/R channels, 16, 18, 20
and 24-bits) or IEC-61937 standard (for compressed data), for F
Sampling frequencies of 96kHz, 48kHz, 44.1kHz, 32kHz and half sampling frequencies are supported. A
downsampling filter (96kHz/48kHz) is available.
The decoder supports dual mode for MPEG and Dolby Digital. It is karaoke aware and capable in Dolby Digital and
MPEG formats according to DVD specifications. It includes a Dolby surround compatible downmix and a ProLogic
decoder.
A pink noise generator enables the accurate positioning of speakers for optimal surround sound setup.
In global mute mode, the decoder decodes the incoming bitstream normally but the PCM and SPDIF outputs are
softmuted. This mode is used to prepare a period of decoding mode, to synchronize audio and video data without
hearing the audio.
Slow-forward and fast-forward trick modes are available for compressed and non-compressed data.
The control interface of the decoder is activated via memory mapped registers in the ST20 address space.
1.5
Karaoke
The karaoke processor is a post-processing module which supports the following features: 2 micro PCM input, pitch
shift, echo effect, reverberation, chorus, voice cancellation, level-sensitive vocal cancelling, vocal partnering,
independant volume control on music and vocal channels.
1.6
Modem analog front-end interface
The Modem Analog Front-end interface is used to transfer transmit and receive DAC and ADC samples between the
memory and an external modem analog front-end (MAFE), using a synchronous serial protocol. DMA is used to
transfer the sample data between memory buffers and the MAFE interface module, with separate transmit and receive
buffers and double buffering of the buffer pointers. FIFOs are used to take into account the access latency to memory,
in a worst case system and to allow the use of bursts for memory bandwidth efficiency improvement. The V22 bis
standard is supported.
1.7
Memory subsystem
On-chip
The on-chip memory includes 2Kbytes of instruction cache, 2Kbytes of data cache and 4Kbytes of SRAM that can be
optionally configured as data cache. The subsystem provides 240M/bytes of internal bandwidth, supporting pipelined 2-
cycle internal memory access.
Circuit-, IC Descriptions and List of Abbreviations
= 96kHz, 48kHz, 44.1kHz or 32kHz.
S
1 Architecture overview
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