Chapter 3: Audio and Video Configuration
Automatic Mode Switching
The XHD-3902 can be configured to operate as an upconverter
(SD-SDI in, HD-SDI out), a downconverter (HD-SDI in, SD-SDI out), a crossconverter (HD-SDI in, HD-SDI out), or an SD-SDI ARC
(SD-SDI in, SD-SDI out).
For applications where a mix of HD and SD signals can be fed to the
XHD-3902 module at any time, automatic mode switching makes it possible for the XHD-3902 to automatically reconfigure itself (that is, change the modes of operation) based on the video standard fed into primary SDI input, in a way that the program output is maintained in the selected output video standard. In any one of these modes of operation, the primary SDI input can accept either SD input or HD input.
NOTE
Aside from film rate compensation, the XHD-3902 does not perform frame rate conversion. Thus, only input standards that have frame rates compatible with the selected output frame rate will trigger automatic mode switches.
Enabling Automatic Mode Switching
Automatic mode switching operation is disabled by default. You can enable this feature using the Automatic Mode Switch parameter (
page
120
). When enabled, the XHD-3902 module will monitor the video standard found on the primary SDI input. When a new video standard is found to be present on the primary SDI input for the duration programmed into the Mode Switch Delay parameter (
page 120 ), a
mode switch will be triggered according to the options shown in
Table 3-2 on page 70
.
NOTE
The XHD-3902 must hold a valid license key for a given mode of operation in order for the automatic mode switch to trigger.
XHD-3902 Installation and Operation Manual 69
Chapter 3: Audio and Video Configuration
Table 3-2. Automatic Mode Switching
Starting Value of x3902Mode Parameter
XHD-3902U
XHD-3902C
XHD-3902D
XHD-3902A
Change of Video Standard on Primary SDI Input
From SD-SDI to HD-SDI
New x3902 Mode Value
Resulting From Automatic
Mode Switch
XHD-3902C
XHD-3902U From HD-SDI to SD-SDI
From HD-SDI to SD-SDI
From SD-SDI to HD-SDI
XHD-3902A
XHD-3902D
Modal Parameter Exceptions
In the XHD-3902, many configuration parameters are allowed to maintain their own values within different modes of operation. Thus the
XHD-3902 remembers the last value configured for parameters such as
Input Select (
page 127
) and Output Video Standard Set ( page 126 ) in
each individual mode of operation (XHD3902U, XHD3902C,
XHD3902D, or XHD3902A), and will recall the saved values
whenever the x3902 Mode ( page 120
) changes.
For Input Select and Output Standard Set, this behavior differs when automatic mode switching is used. Automatic mode switching maintains program output in the same video format regardless of what video format appears on its primary SDI input (subject to supported input formats and frame rates compatible with the selected output frame rate).
The following two exceptions occur whenever a mode switch is triggered via the automatic mode switch mechanism:
• The Output Standard Set value is copied from the mode the
XHD-3902 switches from to the mode it switches to
• The Input Select value in the mode that the XHD-3902 switches to is set to Primary Input
70 XHD-3902 Installation and Operation Manual
Chapter 3: Audio and Video Configuration
Mode Switch Delay
Since a mode switch is a major configuration change, and takes more time than other parameter changes, it is not desirable for transient video standard changes on the primary SDI input to trigger mode switches.
The Mode Switch Delay parameter ( page 120
) is used to prevent such behavior. Whenever a new video standard is fed into the primary SDI input, the XHD-3902 will wait for the input to be present for the number of seconds configured in Mode Switch Delay parameter before it triggers a mode switch operation.
Protected Mode and Automatic Mode Switch
Protected mode failover/recovery and the “-UCD” automatic mode switch both allow modules to automatically respond to changes on SDI inputs. These mechanisms operate independently of each other, even when you enable both of them at the same time. To achieve the desired behavior, you must configure the following two mechanisms and their individual delay parameters:
• Mode Switch Delay for automatic mode switch (
page 120 )
•
Set Failover Delay ( page 127 ) and Recovery Delay ( page 127 ) for
protected mode failover/recovery.
XHD-3902 Installation and Operation Manual 71
