Full screen still graphics may cause encoding issues for 1st gen T-RAX encoder card

Applies to:

• 1st generation T-RAX encoder (starting serial number of 107)

NOTE: this does not apply to T-RAX 700 series encoders (starting serial number of 786)

Overview

Video input material that has a full screen still image (e.g. computer or digital graphics source / PowerPoint slides / off-air notices / station logos) could cause an issue for the hardware encoder chip in the 1st generation T-RAX encoder card where the device may stop encoding video or it may stop responding.

The cause of the issue is that the hardware codec may try to process and encode the digital graphic content at too high of a quality and become unresponsive. 

This issue may not happen every time that full screen graphics are present on the input, and may be more likely to occur the longer the full screen graphic or slide is present on the input.

This issue does not happen with:

• Input that is a mix of still image graphics content and content with motion (such as a picture-in-picture display with video in one area of the screen, or a lower thirds text crawl).
• Input from a camera video source which is pointed at a static / unchanging scene; there is a small amount of noise from the camera sensor which changes the signal sent to the hardware encoder and the encoded content (even if that sensor noise is not visible to the eye).

Workaround

Change the Quantization Parameter (QP) minimum value from the default of 0 to 25 to prevent this issue from happening, as the hardware codec will be prevented from using encoding values which could cause it to reach this state. 

This setting is accessible through the Web User Interface of the T-RAX encoder with the below instructions. 

1st generation T-RAX Encoder

From the Controller Card's Web UI edit the settings of the specific encoder card, then go to Video Setup, Encoder Settings, under Rate Control Options change Rate Control Mode to Manual then change the QP Min value from 0 to 25.

Leave the QP Max and other Rate Control settings unchanged, then Apply.

Restart the video encoding process or reboot the unit.