1998 Sep 07 3
Philips Semiconductors Preliminary specification
Integrated MPEG AVG decoder SAA7212
• Video output direct connectable to SAA718x encoder
family
• Various trick modes under control of external
microcontroller in stand-alone mode:
– Freeze field/frame on I or P pictures; restart on I
picture
– Freeze field on B pictures; restart on the next I or P
picture.
– Scanning and decoding of I or I + P pictures in a IBP
sequence
– Single step mode
– Repeat/skip field for time base correction.
MPEG2 audio features
• Decoding of 2 channels, layer I and II MPEG audio.
Support for mono, stereo, intensity stereo and dual
channel mode.
• Constant and variable bit rates up to 448 kbit/s
• Supported audio sampling frequencies: 48, 44.1, 32, 24,
22.05 and 16 kHz
• CRC error detection
• 3 decoding modes for dual channel streams: decoding
of CH1 only, decoding of CH2 only and decoding of both
CH1 and CH2
• Storage of last 54 bytes in ancillary data field
• Dynamic Range Control (DRC) at output
• Independent channel volume control and programmable
inter channel crosstalk through a baseband audio
processing unit
• Muting possibility via external controller. Automatic
muting in case of errors or data lack.
• Generation of ‘beeps’ with programmable tone height,
duration and amplitude
• Serial two channel digital audio output with 16, 18, 20 or
22 bits per sample, compatible either to I
2
S or Japanese
formats. Output can be set to high-impedance mode via
the external controller.
• Serial SPDIF audio output. Output can be set to
high-impedance mode.
• Clock output 256 or 384 × fs for external DA converter.
Output can be set to high-impedance mode.
• Audio FIFO in external SDRAM. Programmable buffer
size, at least 64 kbit is available.
• Synchronization modes: PTS controlled, PTS free
running, software controlled, buffer controlled
• PTS register can be set via external controller
• Programmable processing delay compensation
• Software controlled stop and restart functions.
Graphics features
• Graphics are presented in boxes independent of video
format
• Screen arrangement of boxes is determined by display
list mechanism which allows for multiple boxes,
background loading, fast switching, scrolling and fading
of regions
• Support of 2, 4, 8-bit/pixel in fixed bit maps format or
coded in accordance to the DVB variable/run length
standard for region based graphics
• Display colours are obtained via colour look up tables.
CLUT output is YUVT at 8-bit for each signal component
thus enabling 16 M different colours and 6-bit for T
which gives 64 mixing levels with video,
(T = transparency).
• Bit-map table mechanism to specify a sub set of entries
if the CLUT is larger than required by the coded bit
pattern. Supported bit-map tables are 16 to 256,
4 to 256 and 4 to 16.
• Graphics boxes may not overlap vertically. If 256 entry
CLUT has to be down loaded, a vertical separation of
1 line is mandatory.
• Optimized memory utilization in MPEG video decoding
allows for a storage capacity of 1.2 Mbit for graphics bit
maps. Flexibility in memory control enables larger
capacity in a lot of applications. Moreover variable
length/run length encoding makes better use of
available memory capacity for graphics bit maps thus
making full screen graphics at 8-bit/pixel feasible.
• Fast CPU access (9 Mbytes/s) enables full 1.2 Mbit bit
map update within 20 ms
• Internal support for fast block moves in external SDRAM
• Graphics mechanism can be used for signal generation
in the vertical blanking interval. Useful for teletext, wide
screen signalling, closed caption, etc.
• Support for a single down loadable cursor of 1k pixel
with programmable shape. Supported shapes are
8 × 128 pixels, 16 × 64 pixels, 32 × 32 pixels,
64 × 16 pixels and 128 × 8 pixels.
• Cursor colours obtained via 4 entry CLUT with YUVT at
6,4,4 respectively 2 bits. Mixing of cursor with
video + graphics in 4 levels.
• Cursor can be moved freely across the screen without
overlapping restrictions.