SAA7134 Philips Semiconductors, SAA7134 Datasheet - Page 33

• Manufacturer Part Number: SAA7134
• Description: PCI audio and video broadcast decoder
• Manufacturer: Philips Semiconductors

Philips Semiconductors
investigated and the signal is properly stereo decoded.
The SAA7134HL supports TV stereo decoding for all
NICAM and dual FM sound systems on-chip. The digital
FM demodulation maintains stable phase accuracy,
resulting into improved channel separation, compared to
traditional analog demodulation. BTSC and EIAJ are
demodulated to mono-aural sound, but stereo decoding
can be added externally.
The SAA7134HL incorporates baseband stereo audio
ADCs, to capture sound signals associated with external
video sources, e.g. camera, camcorder or VCR.
For concurrent capture of audio and video signals, it is
important to maintain synchronization between the two
streams. The spoken word and other sound should match
the displayed picture within a video frame (
The SAA7134HL has special means to lock the audio
sampling clock to the video frame frequency (FLC), so that
a certain fix predefined number of audio samples are
associated with each video field. This is especially
important for video editing, compression and recording,
e.g. time shift viewing. There is no drift between the audio
and video streams, not even for longer recording times.
TV sound offers an audio bandwidth of less than 15 kHz,
that is usually sampled and digitized with 32 kHz. NICAM
as digital sound coding has inherently a 32 kHz sample
rate, locked already on the source side to the video rate.
The digital audio stream can be captured through
dedicated DMA into the PCI memory space, or to the
output in I
processing, e.g. virtual surround sound, or converted to
analog stereo via integrated audio DACs, to feed analog
audio over the loop back cable to the sound card function.
7.7.2
Most operating systems are prepared to deal with audio
input at only one single entry point, namely at the sound
card function. Therefore the sound associated with video
has to get routed through the sound card.
The SAA7134HL supports analog audio pass-through and
the loop back cable on-chip. No external components are
required. The audio signal, that was otherwise connected
to the sound card line-in, e.g. analog sound from a
CD-ROM drive, has to be connected to one of the inputs of
the SAA7134HL. By default, after a system reset and
without involvement of any driver, this audio signal is
passed through to the analog audio output pins, that will
feed the loop back cable to the sound card line-in
connector. The AV capture driver has to open the default
pass-through and switch in the TV sound signal by will.
2002 Dec 17
PCI audio and video broadcast decoder
A
CABLE
2
NALOG AUDIO PASS
S-format to further peripheral digital sound
-
THROUGH AND LOOP BACK
1
/
30
s ‘lip-sync’).
33
7.8
The SAA7134HL is optimum equipped to support the
application extension to capture digital TV signals, e.g. for
VSB (ATSC) or DVB (T/C/S). A hybrid TV tuner for analog
and digital TV broadcast reception usually provides a DTV
signal on low IF, i.e. downconverted into a frequency
range from 0 to 10 MHz. Such signals can be fed to one of
the 5 video inputs of the SAA7134HL for digitizing. The
digital raw DTV is output at the video port, and is sent to
the peripheral channel decoder, e.g. TDA8961 for VSB-8
decoding. The channel decoder provides the sampling
clock via the external clock input pin X_CLK_IN (up to
36 MHz input clock frequency), and adjusts the signal gain
in the tuner or in the video input path in front of the ADC.
Alternatively, the low IF DTV/DVB signal could be fed
directly to the channel decoder, depending on the
capability for digitizing the selected device.
The peripheral channel decoder circuitry decodes the
digital transmission into bits and bytes, apply error
correction etc. and outputs a packed Transport Stream
(TS) accompanied by a clock and handshake signals. The
SAA7134HL captures the TS in parallel or serial protocol,
synchronized by Start Of Packet (SOP), and pumps it via
the dedicated DMA into the PCI memory space. The DMA
definition supports automatic toggling between two
buffers.
7.9
7.9.1
The SAA7134HL incorporates an I
and control peripheral devices such as tuner, DTV/DVB
channel decoder, audio DSP co-processors, etc. The
I
command level, reading and writing byte by byte. The
actual I
an option, can raise error interrupts on the PCI-bus.
At PCI reset time, the I
specific information from the on-board EEPROM to update
the PCI configuration registers.
The I
assume slave operation too. This allows application of the
device in the stand-alone mode, i.e. with the PCI-bus not
connected. Under the slave mode, all internal
programming registers can be reached via the I
with exception of the PCI configuration space.
2
C-bus interface itself is controlled from the PCI-bus on a
2
C-bus interface is multi-master capable and can
DTV/DVB channel decoding and TS capture
Control of peripheral devices
2
C-bus status is reported (status register) and, as
I
2
C-
BUS MASTER
2
C-bus master receives board
2
C-bus master to set-up
SAA7134HL
Product specification
2
C-bus