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G
Video Processor Module
(Continued)
6.2.1
The VIP block is designed to interface the SC2200 with
external video processors (e.g., Geode CS1300 or Sigma
Designs EM8400) or external TV decoders (e.g., Philips
SAA7114). It inputs CCIR-656 Video and VBI data sourced
by those devices, decodes the data, and delivers the data
directly to the Video Formatter (Direct Video mode) or to
the GX1 module’s video frame buffer (Capture Video/VBI
modes). Figure 6-4 shows a diagram of the VIP block.
Video Input Port (VIP)
From the VIP block’s perspective, Direct Video mode is
always on. There are no registers that enable/disable
Direct Video mode. The data source selected at the video
mux (F4BAR0+Memory Offset 400h[1:0]) determines if the
data from the VIP interface is moved directly or must be
captured.
Two FIFOs in the VIP block support the efficient movement
of Video and VBI data. For Capture Video/VBI modes, a
128-byte FIFO buffers both Video and VBI data processed
by the CCIR-656 decoder. For Direct Video mode, there is
a 2048-byte FIFO that buffer the CCIR-656 decoder’s video
data. The FIFOs are also used to provide clock domain
changes. The VIP interface clock (nominally 27 MHz) is the
input clock domain for both FIFOs. For the Capture
Video/VBI FIFO, the data is clocked out using the FPCI
clock (33 or 66 MHz). For the Direct Video FIFO, the Video
data is clocked out using the GX1’s Video port clock (75,
116, or 133 MHz GX1 core clock divided by 2 or 4).
6.2.1.1
As stated previously, Direct Video mode is on by default so
no registers need to be programmed to support this mode
other than to select the direct video data at the video mux.
The video mux control register is located at F4BAR0+Mem-
ory Offset 400h[1:0].
Direct Video Mode
Direct Video mode while supported is not an optimal mode
of operation. The vertical sync signal is affected by this
mode which cause some CRT monitors operate incorrectly.
This mode supports only one vertical resolution and
refresh rate, which is that of the incoming data. Horizontal
resolution can be scaled if desired. Since the incoming
data has odd and even fields, incoming line must be dou-
bled for it to display properly. This is equivalent to the Bob
technique which is explained later in this section.
GenLock
Because video input data from the VIP is sent directly, with-
out significant buffering frame-to-field synchronization is
required with the GX1 module’s graphics data. This syn-
chronization is known as GenLock. The GenLock registers
are located at F4BAR0+Memory Offset 420h and 424h.
Figure 6-4. VIP Block Diagram
CCIR-656
Decoder
Capture Video/VBI
FIFO
Direct Video
FIFO
Capture Video/VBI
Controller and
Bus Master
Capture Video/VBI Data
Fast-PCI Clock
Fast
X-Bus
to
Fast-PCI
Bridge
GX1
Module
Fast-PCI
Direct Video/VBI
Controller
VIP
Data
VIP
Clock
GX1 Video Clock
Direct Video Data
F4BAR2
Control
Registers
Video
Mux
to Video
Formatter
Video or VBI Data
GenLock
Control
Stop DCLK
CRT_VSYNC
VIP_VSYNC
VIP