[Support]: frigate/<camera_name>/<object_name>/snapshot MQTT trigger payload decoding error

[rpanachi]

Describe the problem you are having

The events published on frigate/<camera_name>/<object_name>/snapshot can't be used as MQTT trigger on automations, causing a Can't decode payload error.

Automation yaml:

alias: "MQTT trigger test"
trigger:
  - platform: mqtt
    topic: frigate/doorbell/person/snapshot
action:
  - service: notify.notify
    metadata: {}
    data:
      message: Snapshot triggered
mode: single

Frigate: v5.4.0
Frigate integration: 0.14.1
Home Assistant Core: 2024.6.1
Home Assistant Supervisor: 2024.10.2

Version

v5.4.0

What browser(s) are you using?

Google Chrome 126.0.6478.185

Frigate config file

cameras:
  doorbell:
    enabled: true
    ffmpeg:
      inputs:
        - path: rtsp://admin:[email protected]/Preview_01_sub
          roles:
            - detect
            - record
    detect:
      enabled: true
      width: 640
      height: 480
      fps: 5
    objects:
      track:
        - person

Relevant Frigate log output

2024-10-20 17:10:40.538 WARNING (MainThread) [homeassistant.components.mqtt.client] Can't decode payload
b'\xff\xd8\xff\xe0\x00\x10JFIF\x00\x01\x01\x00\x00\x01\x00\x01\x00\x00\xff
...(many lines of binary data output)
on frigate/doorbell/person/snapshot with encoding utf-8 (for <Job None HassJobType.Callback <function async_attach_trigger.<locals>.mqtt_automation_listener at 0x7f4546de40>>)

Relevant go2rtc log output

n/a

FFprobe output from your camera

n/a

Frigate stats

n/a

Install method

HassOS Addon

docker-compose file or Docker CLI command

n/a

Object Detector

Coral

Network connection

Wired

Camera make and model

Dahua (IMOU)

Screenshots of the Frigate UI's System metrics pages

No response

Any other information that may be helpful

No response

[hawkeye217]

The MQTT payload is base64 image data, so you'd need to use a notify service that supports images. For example, this is how it works for iOS:

action:
  - service: notify.mobile_app_<your_device>
    data:
      message: Snapshot triggered
      data:
        image: /api/frigate/notifications/<event_id>/thumbnail.jpg

[rpanachi]

The error occurs when home assistant try to decode the MQTT topic payload to trigger the automation.

In other words, the automation wasn't triggered because this payload decode error. The error wasn't on the action of the automation, but in the trigger (from a mqtt event).

[hawkeye217]

Yes, because what's being sent on the /snapshot topic is binary image data.

You should trigger based on the /events or /reviews topic instead. See the docs.