Kramer Electronics SP-14 - Manual (Page 28)

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Group 1 Input from SDI, Group 2 Input from SDI
An SDI signal may carry 8x two channel audio signals.
The SDI receiver used in SP-14 is only capable of making 4x two channel audio signals available to the
audio processing system at a time. This menu item allows to route certain SDI audio groups to the audio
input channels of the SP-14 audio processing system.
SDI audio channels typically use the following nomenclature for the audio channels in sequential order:
Group 1 Pair 1, Group 1 Pair 2, Group 2 Pair 1, Group 2 Pair 2, Group 3 Pair 1, Group 3 Pair 2, Group 4
Pair 1 and Group 4 Pair 2.
Our 4x two channel AES audio ports and the 8x (single) HDMI audio channels are identified as
Input/Output Pair 1, Input/Output Pair 2, Input/Output Pair 3, and Input/Output Pair 4 in the menu
system. In the SDI routing menu we use the terms Group1 (1,2), Group2 (3,4), Group3 (5,6), and
Group4 (7,8) for the selectable items to make the connection to our pair terminology.
When Group 1 Input from SDI and Group 2 Input from SDI are set to auto, the system will route the first
4x two channel SDI audio signals (which actually transport audio) to the 4x Input Pairs of the SP-14
audio processing system. This can be overwritten, e.g. Group 3 SDI audio can be put on our Input Pair
1 and Input Pair 2 and Group 4 SDI audio can be put on our Input Pair 3 and Input Pair 4.
4.9.2.
HDMI EDID control and Audio Delay
HDMI Audio Input
Allows the user to set the format of the HDMI audio channel. Use to choose how many channels of
audio are requested from the HDMI source equipment. By default the processor allows 8 channels (7.1)
of audio to be sent by a source. This EDID information can be overwritten to reduce the number of
incoming channels.
Audio Delay
The audio delay is automatically set to compensate for the latency through the unit. The Audio Delay
adjustment does not override this automatic setting but allows fine calibration of the audio delay in steps
of approximately 1mS, to advance or retard the audio so as to compensate for further delays in your
display device or your audio system.
4.10.
Closed Captioning
SP-14 can receive and transmit closed captioning information. CEA-608 CC information can be
received on the Composite, S-Video and Component inputs. For 480i/NTSC line 21/284 are scanned for
CC information.
SMPTE 334M ancillary data packets with CEA-608 information (SDID = 0x02) or CEA-708 CC
information (SDID = 0x01) incl. embedded CEA-608 CC data can be received on the SDI inputs. The
CEA-608 CC information is extracted and put on the component output when output resolution is set to
480i. The whole packet is passed through unchanged to the 3GSDI output port for all output formats
set.
CEA-608 CC information from the analogue inputs is transmitted on the YPbPr output when set to 480i
output resolution (on line 21/284). On the 3GSDI output closed captioning information is put into a
SMPTE 334M packet (SDID = 0x01) as embedded CEA-608 CC information and also transcoded to
equivalent CEA-708 CC information. This packet gets sent on the SDI output for all output formats.
SP-14 by means of a menu item allow the user to select the CC standard to use for the 3GSDI output,
when the output format is 480i or 576i. The choice available is either CEA-708 encoded CC data (which
includes embedded CEA-608 codes)
– the default; or original CEA-608 data, which is sent in a packet
as described in Annex A of SMPTE 334-1. The user might need this second option if the output is
feeding legacy equipment that does not understand the newer CEA-708 formats.
The CC processing code supports any combination of input and output (subject to hardware limitations
of which channels actually support CC).
CC messages are drip fed, especially for CEA-608, which gives a fixed rate of two characters per field,
every field (each pair could be text, or a control code, or just nulls to fill the space until the next
message). So, if you convert a high-field rate input to a low rate output, then the nulls between
messages will be reduced so each message starts in about the same place in the video sequence.