VDP 3108
ADVANCE INFORMATION
2.3. Digital Video Interfaces
Via the MSY line, serial data is transferred which con-
tains information about the main picture such as current
line number, odd/even field etc.). It is generated by the
deflection circuitry and represents the orthogonal time-
base for the entire system.
The digital video interface allows insertion of digital data
in YC C format on the internal YC C data bus. The ort-
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hogonal data structure of this bus is the ideal interface
point to external data sources and sinks. On top of this,
a host of formats are supported, e.g. support of level-2
teletext or the priority pixel bus concept.
Feature ICs (e.g. PIP) will be synchronized to the main
YC C bus. Digital insertion (boxing) is controlled by a
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priority system.
Figure 2–13 shows all available digital interfaces:
YC C 16 bit 4:2:2
RBG 5 bit 4:4:4
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2.3.2. Digital RGB Interface
PRIO 3 bit, source selection
Digital RGB from text or on-screen-display is connected
via the Picture bus. The RGB signal is 5 bits wide. The
RGB signals are not subject to any post-filtering. The
RGB signal provides 3–bit RGB (one bit per color), the
4thbitallowstodisplayhalfcontrastcolors. Bit5enables
aprogrammablecolor–look–uptablewith16entriesand
4 bit resolution per color. This allows the support of a
WorldSystemTeletextlevel-2colordisplay. Displaycon-
trast for RGB data can be adjusted separately by three
contrast multipliers.
The YCrCb bus is used for video insertion. The RGB in-
terface is used for insertion of a Teletext or OSD picture.
The priority bus allows to mix up to 8 sources on the
YC C / RGB bus.
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VDP
Video Display Pro-
cessor
2.3.3. Priority Codec
CCU/
OSD
Up to eight digital YC C or RGB sources (main decoder,
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PIP, OSD, Text, etc.) may be selected in real-time by
means of a 3-bit priority bus. Thus a pixelwise bus arbi-
tration and source switching is possible. It is essential
thatallYC C -sources are synchronous and orthogonal.
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Ingeneraleachsource(=master)hasitsownYC C bus
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PIP
TPU
request. This bus request may either be software or
hardware-controlled, i.e. a fast blank signal. Data colli-
sion is avoided by a bus arbiter that provides the individ-
ual bus acknowledge in accordance to a user defined
priority.
Fig. 2–13: VDP video interfaces
Each master sends a bus request with his individual
priority ID onto the PRIO-bus and immediately reads
back the bus status. Only in case of positive arbitration
(send-PRIO-ID = read-PRIO-ID) the bus acknowledge
becomes active and the data is sent.
2.3.1. Picture Bus Interface
The picture bus format between all DIGIT3000 ICs is
YCrCb with 20.25 Msamples/s. Only active video is
transferred, synchronized by the system main sync sig-
nal (MSY) which indicates the start of valid data for each
scan line. The number of active samples per line is 1068
for all standards (525 and 625).
This treatment has many features that have impact on
the appearance of a TV picture:
real-time bus arbitration (PIP, OSD, ...)
priorities are software configurable
different coefficients for different sources
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MICRONAS INTERMETALL
MICRONAS [ MICRONAS ]
