Synchronized Content
Example: JavaScript
The following example shows the usage of the JavaScript MULTI_SCREEN_ID variable to control the text content of a textArea item.
<spx:multiScreen>
<spx:screen viewBox="0 0 1280 720" xml:id="left"/> <spx:screen viewBox="0 0 1280 720" xml:id="right"/> </spx:multiScreen>
<script>
<![CDATA[
if (MULTI_SCREEN_ID == "left") document.getElementById("textId").textContent="I'm left!"; else if (MULTI_SCREEN_ID == "right") document.getElementById("textId").textContent="I'm right!"; else
document.getElementById("textId").textContent="No screen defined!"; ]]>
</script>
<g>
<text x="50" y="50" xml:id="textID">_Text_will_be_here_</text> </g>
Troubleshooting
Synchronized content over multiple screen needs a correct configuration of the
NTP Synchronization
The content are not synchronized, i.e. one or more screens play their part of media earlier or later than the other displays. Please check the following:
Make sure that NTP is enabled through the
It should be on your local network in order to be able to achieve the few milliseconds of precision required. Public NTP servers are usually too “far” to provide such a precision. Please refer to the Synchronization on page 52 for details on inserting NTP server addresses.
Verify your
Values in the column “Time offset” should be as close to 0 as possible.
Make sure that at least one NTP server is always reachable (at least one column “Reach” should be equal to 100%).
In case your NTP server can't be reached (“Status” column remains always “Initializing”), it may be behind a firewall or
just wrongly configured. Check the NTP server configuration with your system administrator. For further details on the NTP protocol, please refer to http://www.ntp.org.
If you used the master/slave configuration, be careful to correctly implement the architectures covered in the Using an
configurations ("Monitor only" NOT selected).
Project Creation
Verify that your index.svg file contains the spx:begin attribute, or that your project uses a schedule file (.ics), as explained in the Syntax for Multiscreen Synchronized Content on page 56. A good test to verify if your content uses a begin attribute or a calendar is to open the index.svg file in XPress. If your project starts from the beginning, then no
schedule is present.
If opening the project multiple times always shows the same starting point, then no schedule is present and the playback will not be synchronized.
Internal Clock Calibration
The local clock on the device is not calibrated when shipped from the factory. NTP behaves differently when the local clock has not yet been calibrated, and it will not synchronize as expected. Figure 20 below shows the configuration window before calibration is completed.
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