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Triggers

Triggers are a log line analysis mechanism in Senta that allows automatic execution of actions when specific conditions are detected.

The main purpose of triggers is to monitor stream status and automatically restart streams when problems are detected.

The system supports two types of triggers:

  • Static
  • Dynamic (custom)

Static Triggers

Section titled “Static Triggers”

Static triggers are built into the system. Currently, one static trigger is available — the bitrate analysis trigger.

Static Bitrate Trigger

Section titled “Static Bitrate Trigger”
  • Has a fixed ID = 1
  • Pre-installed in the system
  • Cannot be deleted
  • Can be assigned and unassigned from channels

How It Works

Section titled “How It Works”

Despite the name, the trigger doesn’t actually parse or compare bitrate values — it doesn’t measure stream parameters through any external means (e.g. ffprobe) at all. Its only source of data is the text progress output the ffmpeg process itself prints: the trigger watches the time= field in that output (the timestamp of the last frame processed). If that timestamp stops advancing between log lines, ffmpeg is stuck — even though the process is technically still running — and the trigger treats it as a stream freeze.

In such cases, the trigger automatically performs a stream restart.

How to Assign a Static Trigger

Section titled “How to Assign a Static Trigger”

  1. Go to the Triggers page

  2. Select the Bitrate trigger

  3. Check the boxes for the desired streams in the stream list

  4. Save changes

After this, the selected channels will be automatically monitored for bitrate.

Dynamic (Custom) Triggers

Section titled “Dynamic (Custom) Triggers”

Dynamic triggers allow you to create your own log analysis rules.

The system can:

  • search for substring occurrences in log lines
  • check log lines against regular expressions

When a condition matches, a specified action is executed (e.g., stream restart).

Creating a Custom Trigger

Section titled “Creating a Custom Trigger”

To create a new trigger:

  1. Go to the Triggers page

  2. Click Add trigger

    Add trigger from triggers page

  3. Enter the trigger name

  4. If necessary, enable the Regular expression option

  5. Enter the text to look for, in the Substring match field (or Regular expression, if you enabled that option above — the field’s label changes accordingly)

    Configure new trigger

  6. Save the trigger

  7. Select the list of streams to which this trigger should be applied

After saving, the trigger will start analyzing logs of the selected streams.