SAA7174 Datasheet, PDF (3/4 Pages) NXP Semiconductors – Analog TV video and stereo decoder for computing and consumer applications in Europe

two analog audio
stereo pairs
TV sound (SIF)
five analog
video inputs:
CVBS, S-Video
GPIO
interrupt
SAA7174
analog audio pass-through
ANALOG
AUDIO
INTERFACE
ANALOG SIF/
AUDIO INTERFACE
ANALOG
VIDEO
INTERFACE
32kHz, 44.1 kHz, 48 kHz
SOUND DECODER
(NICAM, A2/Dual-FM)
AUDIO FEATURE
PROCESSING
(volume, balance)
DECODER
COMB FILTER
VIDEO
SCALER
MATRIX &
GAMMA
CLOCK SYNC
PROGRAMMABLE I/O
IRQ SELECTION/MAP
PROGRAMMING
REGISTERS
DAC (2) AUDIO MUX
I²S
analog stereo to
loopback cable
or headphones
digital audio
VIDEO PORT
FORMAT
I²C INTERFACE
digital video
control data,
I2C
config data
from EEPROM
SAA7174 conceptual block diagram
Video output
Decoded, scaled video is output through a digital video output
port in various YUV or RGB formats including packed and pla-
nar, gamma-compensated, or black-stretched.
Stereo audio capture, decode, and output
The SAA7174 handles capture and on-chip decoding of the TV
stereo audio formats used throughout Europe (NICAM and A2/
Dual-FM). After capture from the TV tuner through a SIF (Sound
Intermediate Frequency) port,TV stereo audio is digitized and
FM or AM demodulated.The audio standard is detected, the pilot
tone is investigated (mono, stereo, dual), and the signal is decoded.
Two 16-bit audio ADCs support capture of sound signals from
nonstandard sources such as video cameras, VCRs, and AM
(mono) or FM (stereo) radio through two stereo line-in inputs.
A field-locked audio sampling clock supports a constant number
of audio clocks per video field, guaranteeing synchronization of
audio and video streams. The SAA7174 also performs on-chip
volume and balance processing.
Decoded digital audio is output through an I²S port. Alternatively,
it can be reconverted to analog by on-chip stereo DACs and
rerouted through a loop-back cable to a sound card.
Audio passthrough
To support legacy analog audio, the SAA7174 also provides line-
level input and pass-through of analog audio signals. After capture
through two pairs of line-level stereo inputs (with source select),
mono audio signals are directly routed through a loop-back cable
to a sound card for further processing or output. No external
components are required.
VBI capture
The SAA7174 captures raw VBI samples that can be provided to
software components for decoding. The VBI sampling rate can be
adjusted by the data slicing software. Supported VBI formats
include Closed Captioning,Teletext,WST, NABST, CGMS, and WSS.
Versatile external interface
The SAA7174's flexible design, reusable components, and versatile
external interfaces lower BOM and cost and support advanced
decoder configurations. Such flexibility is made possible, in part,
through 28 general purpose I/O (GPIO) pins, initially dedicated to
provide a digital video port and peripheral interrupt input. GPIO
pins can be reassigned if dedicated functions are not needed in a
specific product configuration. In addition, unassigned pins can be
utilized for GPIO under direct software control.