GS1560A/GS1561 Data Sheet
3.10.3 SMPTE 352M Payload Identifier
The GS1560A/GS1561 can receive and detect the presence of the SMPTE 352M
payload identifier ancillary data packet. This four word payload identifier packet
may be used to indicate the transport mechanism, frame rate and line scanning /
sampling structure.
Upon reception of this packet, the device will extract the four words describing the
video format being transported and make this information available to the host
interface via the four VIDEO_FORMAT_OUT registers (Table 3-6).
The VIDEO_FORMAT_OUT registers will only be updated if the received
checksum is the same as the locally calculated checksum.
These registers will be cleared to zero, indicating an undefined format, if the device
loses lock to the input data stream (LOCKED = LOW), or if the SMPTE_BYPASS
pin is asserted LOW. This is also the default setting after device reset.
The SMPTE 352M packet should be received once per field for interlaced systems
and once per frame for progressive systems. If the packet is not received for two
complete video frames, the VIDEO_FORMAT_OUT registers will be cleared to
zero.
Table 3-6: Host Interface Description for SMPTE 352M Payload Identifier Registers
Register Name
Bit
Name
Description
R/W
Default
VIDEO_FORMAT_OUT_B
Address: 00Dh
15-8
SMPTE352M
Byte 4
Data will be available in this register when Video Payload
Identification Packets are detected in the data stream.
R
0
7-0
SMPTE352M
Byte 3
Data will be available in this register when Video Payload
Identification Packets are detected in the data stream.
R
R
R
0
0
0
VIDEO_FORMAT_OUT_A
Address: 00Ch
15-8
7-0
SMPTE352M
Byte 2
Data will be available in this register when Video Payload
Identification Packets are detected in the data stream.
SMPTE352M
Byte 1
Data will be available in this register when Video Payload
Identification Packets are detected in the data stream.
3.10.4 Automatic Video Standard and Data Format Detection
The GS1560A/GS1561 can independently detect the input video standard and
data format by using the timing parameters extracted from the received TRS ID
words. This information is presented to the host interface via the
VIDEO_STANDARD register (Table 3-7).
Total samples per line, active samples per line, total lines per field/frame and active
lines per field/frame are also calculated and presented to the host interface via the
RASTER_STRUCTURE registers (Table 3-8). These line and sample count
registers are updated once per frame at the end of line 12. This is in addition to the
information contained in the VIDEO_STANDARD register.
After device reset, the four RASTER_STRUCTURE registers default to zero.
27360 - 8 September 2005
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