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HDMI Troubleshooting for Strato

In installations that pass Ultra HD video signals through multiple devices like matrix switches, it can be challenging to achieve reliable HDMI performance. This page discusses how to troubleshoot interoperability issues. Consult the Kaleidescape Support pages entitled Strato and Ultra HD Video Standards and HDMI Best Practices for Strato for context.

Things to Try

Most types of HDMI issue can be avoided by choosing the right HDMI cable solution. Please see Kaleidescape Recommended HDMI Cables for information on how to choose the right cable solution. If the HDMI cable solution is working well and if all components support HDMI 2.0 and HDCP 2.2, HDMI problems should be rare.  However, if they do occur, here are some things you can try.

Check HDMI Port Capabilities

Some display devices and A/V components do not support 18Gbps HDMI 2.0 and HDCP 2.2 on every port.  This includes certain Sony displays.  Ensure that you are using an HDMI port that supports 18Gbps HDMI 2.0 and HDCP 2.2.

Check Device Settings

Some display devices modify their HDMI behavior based upon user settings.  For example, some Samsung displays have an “HDMI UHD Color” setting that must be enabled before the display will accept an 18 Gbps signal, and some Sony displays have a similar “HDMI signal format” setting.

Check Device Software/Firmware

4K Ultra HD – especially at 18 Gbps data rates – is a new and demanding format.  Some displays, audio processors, or other components may need software or firmware updates to handle it properly.  Check with manufacturers to ensure that the software in all of your components is up to date.     

Use the HDMI Capabilities Tool

In Strato’s Browser Interface, the video configuration page has an HDMI Capabilities tool. This is an extremely handy feature that reveals the HDMI capabilities of the attached HDMI display,  and it can be refreshed as the connection is changed, or during movie playback. For more details, see Verifying HDMI Video Performance.

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Select Show primary HDMI port capabilities and status to bring up the HDMI Capabilities window.

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Verify that the Supported 4K Ultra HD Modes and the Supported HDMI Features match the published specifications of your display device.  If they do not, the display may be incorrectly reporting its capabilities, or an intermediate device like an AV receiver may not equal the capabilities of your display.  Double-check the intermediate devices, and consider temporarily connecting Strato directly to the display to help isolate the problem.  You can also consider using the Advanced Video Settings (described below) to override some features.

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The HDMI Video Output Status shows the video attributes of both the media (or OSD) and the output. Select Refresh to update these values at any time.

Check HDCP Status

If the onscreen display works properly, but you get video dropouts, a red screen, or no picture at all when playing a movie, the problem may be related to HDCP copy protection.  The onscreen display does not require HDCP, but movie playback does.  The HDMI Capabilities Tool should give you an indication of HDCP status during movie playback (click Refresh if necessary).  Sometimes a marginal cable will pass a video signal, but be unable to maintain the HDCP connection.

Try Alternate Cables

Problems with signal integrity, such as signal loss in a long cable, may also affect Strato’s ability to detect display capabilities and achieve an HDCP connection with the display.  Try connecting Strato to the display using a different cable, or try temporarily relocating Strato and using a shorter certified cable to see if the problem goes away.

Reduce HDMI Bandwidth

Intermittent problems are almost always related to signal integrity.  The display and intermediate devices may all support 18 Gbps connections, but the cable may be unable to carry that speed reliably.  You can try temporarily forcing Strato to use 13.5 Gbps or 10.2 Gbps instead.  This can help to identify whether the problem is related to signal transmission.

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To force Strato to use a lower-bandwidth connection, go to the system’s Browser Interface, and click on the Settings tab.  You should see the Components page as above.  In the section for your Strato, click the Settings button.

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In the window that opens, scroll to the bottom and click Show Advanced Video Settings:

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Scroll down to 4K Ultra HD Support, and click the radio button next to Limit output to 13.5Gbps or Limit output to 10.2Gbps.  Try 13.5 Gbps first, since this imposes fewer limitations on how content is displayed. Once you’ve clicked OK to save the setting, stop the movie if it was playing, and then try playing it again – it should play at a reduced bandwidth that may avoid interoperability issues.
These advanced settings can also be used to compensate for problems that arise when a display or intermediate device does not correctly report or pass EDID information.

Changes in the HDMI Display Chain During Playback

In installations that involve an HDMI matrix switch, it is possible for an HDMI device to join the display chain while movie playback is occurring.  For example, a second zone may also select the first zone’s video source. If the first zone supports HDMI 2.0 and HDCP 2.2 but the newly added zone does not, the addition of the second zone will cause the HDCP 2.2 link to become invalid.  Video in the first zone will go blank, and the second zone will also see no video signal.  If playback is stopped and then resumed, Strato will have an opportunity to reconfigure the HDMI output and playback may be able to proceed (although at reduced resolution for 4K Ultra HD content). Try to avoid situations in which different HDCP and HDMI versions may come and go, to avoid disruptions to the viewing experience.


Troubleshooting Checklist

The following checklist can be used to solve HDMI interoperability issues. If these options are exhausted, note the results of each test for subsequent discussion with the Kaleidescape Support team.
1. Cable inspectionAll cables are in good condition and securely plugged in. For directional cables, ensure the Source and Display connectors plug in to the corresponding devices. 
2. Cable certificationAll cables meet Kaleidescape’s criteria for passing 4K 18 Gbps signals, as outlined in the Cables section above. 
3. HDMI Capabilities ToolThe HDMI Capabilities tool in Strato’s Browser Interface shows passing grades for all relevant signal attributes, e.g. HDCP Status. Click “Refresh” during movie playback. 
4. Firmware for the displayFirmware is up-to-date on the display or projector. 
5. Firmware for intermediate devices in the A/V pathFirmware is up-to-date on AV receivers, matrix switches, etc. 
6. HDMI port capabilities on the displayThe display’s manual says the specific HDMI input in use supports 18 Gbps HDMI2.0/HDCP2.2 signals. 
7. “UHD Color” setting on the displayThe display’s “UHD Color” or “HDMI Signal Format” (Sony) or “HDMI Mode 2” (Panasonic) setting is enabled - this triggers support for 18 Gbps signals. 
8. Strato direct connection to displayStrato has been connected directly to the display via a known-good cable. 
9. Strato connection to a minimal number of devicesIf Strato works direct to the display, add one device at a time to restore the full video path. Note the first device that triggers errors. 
10. Strato video at 10.2 GbpsVideo capabilities in Strato’s Browser Interface have been set to the 10.2 Gbps setting. 
11. Strato video at 13.5 GbpsVideo capabilities in Strato’s Browser Interface have been set to the 13.5 Gbps setting. 
12. Allow Display Mode ChangesVideo capabilities in Strato’s Browser Interface have been set to “Allow Display Mode Changes”. Both SDR and HDR movies have been played. 
13. Allow Display Mode Changes (use external scaler)Video capabilities in Strato’s Browser Interface have been set to “Allow Display Mode Changes (use external scaler)”. A variety of SD/HD/UHD/HDR movies have been played (in their native formats). 
14. Cable swappingEach cable in the video path has been swapped out for a known-good or shorter cable. Use the HDMI Capabilities Tools to verify HDCP status. 
15. Single zoneSecondary zones have been disconnected so as to create a single video path. 
16. Single HDMI/HDCP versionMatrix-switched devices that could cause HDMI/HDCP version changes during playback have been disconnected. 


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