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2004 Jan 26 16
Philips Semiconductors Product specification
MPEG-2 video and MPEG-audio/AC-3
audio encoder with multiplexer
SAA6752HS
7.1.3 MODE TRANSITION COMMANDS
There are seven mode transition commands:
1. SOFT RESET. Like a hard reset, a soft reset can be
applied in any mode, setting the SAA6752HS back to
Idle mode and resetting all configuration parameters
back to the default settings.
2. RECONFIGURE. This command sets the
SAA6752HS back to Idle mode without resetting the
configuration parameters back to the default settings.
3. ENABLE. This transition sets Stop mode, enabling the
video and audio input processing.
4. START. This transition sets Encode mode, enabling
the multiplexer stream output. Note that if the
SAA6752HS is commanded to start from the Idle
mode, then the internal transition is via the Stop mode.
5. STOP. This command will disable the multiplexer
stream output, setting the SAA6752HS to Stop mode.
The current GOP and/or audio frame is completed and
an end of sequence bit appended to the stream.
6. PAUSE. A PAUSE transition will cause the multiplexer
to complete the current GOP and/or audio frame but
no end of sequence bit is appended. The current
MPEG buffer model contents are saved to provide a
seamless transition on START.
7. SLEEP. This mode disables the internal clock.
8. FORCED RECONFIGURE. A STOP command whilst
in the Encode mode will not work in case the video or
audio input signal is interrupted, because for stopping,
the SAA6752HS tries to finish the current GOP. The
forced reconfigure command allows a mode transition
back to the Idle state, without losing the actual
configuration settings. The forced reconfiguration
performs a soft reset and the automatic internal
reprogramming of the I
2
C-bus registers. The forced
reconfiguration will take about 200 ms; during the
forced reconfiguration all register values will change to
their default values before they are reprogrammed.
Please note that outputs, which can be switched to
high-impedance or to input mode, will not be active
during the forced reconfiguration.
The SAA6752HS is not able to process any other
commands during mode transitions. In this event, a get
running mode request will return a busy flag. The
completion of a mode transition can also be flagged as an
event using the host interrupt pin.
7.2 Digital video input
7.2.1 GENERAL
The video front-end processes an
“ITU-R BT.601/605”
compliant video stream for conversion to 4 :2:0 format
(MP@ML). It includes synchronization, digital video signal
processing through several filters, subsampling, sliced/raw
VBI data handling, and SDRAM address generation.
The video interface is designed for use with Philips
SAA7114 digital multi-standard decoder or similar video
decoders. The input interface accepts a digital video input
stream according to
“ITU-R-BT.601”
. 625 lines standard at
50 Hz and 720 pixels by 576 lines as well as 525 lines at
60 Hz and 720 pixels by 480 lines are covered. The video
synchronization may either follow
“ITU-R-BT.656”
recommendation or can also be supplied by external
signals (HSYNC, VSYNC and FID). The formatter module
performs a colour conversion from 4 :2:2to4:2:0
format. Optionally, also SIF progressive downscaling and
2/3D1, 1/2D1 downscaling may be activated.
The SAA6752HS supports non-standard features of the
SAA711x series of video input processors, such as
hard-wired external synchronization signals (2 and 3-wire
sync), special VCR playback signal streams (IEC 756
subset for VCR playback and still pictures), extraction of
sliced data from the input video stream.
7.2.2 VIDEO FRONT-END CONFIGURATION OPTIONS
The following configuration options can be selected from
the host:
• VIDEO INPUT PORT SELECTION. Two input clock pins
are selectable.
• VIDEO INPUT FORMAT. 525 or 625-line formats can be
selected.
• VIDEO SYNC FORMAT. Various combinations and
polarities of HSYNC, VSYNC and Field Information
(FID) can be selected as the source of sync signal
processing.
• VIDEO FILTER SETTINGS. Noise pre-filter and
horizontal filters can be enabled and, if the default
coefficients are not suitable for an application, new
coefficients can be set.
• VIDEO FORMAT CONVERSION. Selection of
conversion from D1 to 1/2D1, 2/3D1 or SIF progressive
downscaling.
• VBI DATA EXTRACTION. VBI data extraction of WSS
or CC data can be enabled.