Circuit Descriptions, Abbreviation List, and IC Data Sheets
EN 212 JL2.1E AA9.
Video Selectors
The CVI switch (Composite Video Input, including RGB, YUV,
and YPbPr) is selecting the signal from one of the two CVI
inputs; the output is always a YUV signal.
The primary video selector is selecting a signal from the CVBS
and YC inputs; the video coding of the output signal equals to
the video coding of the input signal.
The primary video selector has an extra input (YC_COMB),
capable of selecting an Y/C signal from the comb filter. This
input cannot be downscaled to a CVBS signal and fed back to
the CVBS_A or CVBS_B output. It is also advisable not to
connect other sources to the YC_COMB input because it is
treated as an internal one that is not available for the outside
world.
Two video output selectors are responsible for the contents of
CVBS_A and CVBS_B video out.
Audio Selectors
The primary audio selector is selecting a signal from five
external stereo inputs and one stereo input that handles two
mono signals (AM internal and AM external). The AM internal
signal is demodulated in the IF part and is internally routed, so
not available as external input. Additionally, the AM internal
signal is available on the left channel whereas the AM external
signal is available on the right channel.
The secondary audio selector is selecting a signal from the
same range as the primary audio selector; the second audio
selector can work in stereo or mono mode. In case the stereo
mode is selected, it is alike the primary audio selector. In mono
mode, the input stereo signal L+R is transformed into a mono
signal (L+R)/2 and put on the left channel of the stereo output.
When the stereo input (handling two mono signals) is selected
and the selector works in mono mode, the AMint and AMext
can be swapped on the primary as well as on the secondary
audio channel. It is also possible to digitize the mono + AM on
the secondary audio channel.
Further it is possible to select the AM signal on the analog
audio outputs independently from the AM signal that is selected
for the secondary (digital) audio channel.
Three audio output selectors are responsible for the content of
the Line, SCART1, and SCART2 outputs. These selectors
allow selection of the output out of five L+R inputs, two mono
signals (AM internal or AM external) and two externally
connected DSND streams.
SIF Switching
SIF (Sound Intermediate Frequency) switching allows
selecting between internal or external SIF signals.
AD Converters
The second part of the MPIF is responsible for conversion of
the chosen signals into digital signals and grouping them into
three data streams. Each data stream handles both video and
audio. These data streams are fed into three data links and
send via I2D to the outside.
The MPIF contains four video ADCs for analog and digital
video broadcast signals. The clock frequency for these ADCs
is either 27 MHz or 54 MHz. In some cases, two analog signals
are multiplexed at the input of one ADC. In these cases, the
clock frequency of the ADCs is 54 MHz, while the sample
frequency for each of the two signals is 27 MHz.
The sample frequency for standard 1fH video signals is 27
MHz. For the YUV channel the sample frequency of the U and
V components is half the sample frequency of the Y signal.
For 2fH YPbPr or RGB input signals (for instance 480p or 1080i
ATSC signals), the frequency that is used to sample the YUV
signals is twice as high as for 1fH signals. The sample
frequency is 54 MHz for Y and 27 MHz for U and V.
Due to the high sample frequency, two data links are needed
for transport of the video data to the digital video processor.
I
2
D Data Link
The digital interface between MPIF and AVIP is called Data
Link (or I
2
D Link). This is a serial interface that transfers the
data from MPIF to AVIP over three Data Link interfaces. Each
Data Link has a data signal and a strobe signal. The
synchronization information is distributed over the data and the
strobe signal. To minimize EMC, both signal outputs are low
voltage differential swing signals, with a swing of about 300
mV.
Each Data Link has four lines, one differential pair for the data,
and one differential pair for the strobe. The data rate is 594
Mbit/s. Each Data Link can carry two 27 MHz sampled video
streams (or one 54 MHz sampled 2fH video stream) and two
audio channels sampled at 6.75 MHz.
In the MPIF, the (video and audio) data to be transmitted is
multiplexed in an output register of 44 bits (including the 2 bit
sync information). The content of that 44 bits register is serial
transmitted on one of the three data links. In the AVIP, the
serial data is de-multiplexed into parallel streams. The data on
the data link is divided in several groups of signals (video, audio
and strobe signals). Obvious it is important that the transmitter
and receiver are in the same transmitting mode
Data links can operate in two different modes called:
1. Normal mode.
2. YUV2fH.
Normal Mode
In the normal mode the content of the data links is as follows:
Table 9-2 Normal mode
In the normal mode the data links can handle up to three video
signals: CVBS or YC signal from the primary video selector,
CVI 1fH source selected on the CVI switch, and CVBS signal
from the secondary video selector.
YUV 2fH Mode
In the YUV 2fH mode (higher bandwidth signal) the data links
content is as follows:
Table 9-3 YUV 2fH mode
The data link 1 can output only one of two input signals: the
output of the primary video selector or the Y output of the CVI
switch. Only one can be active at a moment, and that is
determined by the data link mode bit (DM). It means, that for
data links working in YUV 2fH mode, the data link 1 carries the
Y component of the YUV 2fH signal, the data link 2 carries the
UV component, and the data link 3 contains the signal that is
connected through the secondary video selector.
Data Stream Video Audio
1 CVBS/YC primary (L+R) primary
2 YUV 1fH (L+R) secondary
3 CVBS secondary SIF
Data link Mode bit: DM= 0
Data Stream Video Audio
1 Y 2fH (L+R) primary
2 UV 2fH (L+R) secondary
3 CVBS secondary SIF
Data link Mode bit: DM= 1
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