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updatedAt: 2025-11-11T01:47:46.000Z
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Fetch the complete documentation index at: https://docs.formant.io/llms.txt. Use this file to discover all available pages before exploring further. Append .md to any documentation page URL to get its markdown version.

# Agent FAQ

## Can I limit the Formant agent's bandwidth usage?

Formant provides a few bandwidth control options:

### 1. Update the Formant agent

In release 1.91 we introduced new protocols between the formant-agent and the backend that reduce the usage of the formant-agent. Update the agent by runing `sudo apt update && sudo apt upgrade formant-agent`

### 2. Low Bandwidth Mode

After release 1.91, in your device's general settings, you can put the formant-agent in low bandwidth mode. This significantly reduces the amount of data the formant-agent uses for its passive duties (i.e., checking in with the formant-cloud)

<Image title="Screen Shot 2022-09-28 at 3.25.57 PM.png" alt={1418} align="center" width="smart" src="https://files.readme.io/85a9dba-Screen_Shot_2022-09-28_at_3.25.57_PM.png" />

### 3. Rate Limiting

Each data stream can be rate-limited, so you don't need to ingest data at high resolution if you don't need it. Find this in the settings for each stream.

<Image title="Screen Shot 2022-09-28 at 3.27.08 PM.png" alt={1258} align="center" width="smart" src="https://files.readme.io/5bc85c8-Screen_Shot_2022-09-28_at_3.27.08_PM.png">
  In the settings here, we are limiting this stream to 1Hz
</Image>

### 4. On Demand

Each data stream can be set to on-demand, so it is only ever uploaded if specifically requested (from the Formant UI, or programmatically, or by an event)

### 5. Video Encoding

Instead of using compressed/raw image streams, the formant-agent can encode the video for you to significantly reduce the bandwidth of these streams. This is selected in the video encoding settings on an image stream.

<Image title="Screen Shot 2022-09-28 at 3.28.28 PM.png" alt={1202} align="center" width="smart" src="https://files.readme.io/9b85e5b-Screen_Shot_2022-09-28_at_3.28.28_PM.png">
  Here the stream of images has been encoded into a 360p video, reducing bandwidth.
</Image>

## How can I make the "formant" user use a different python than the system level python?

For native installations, export `FORMANT_AGENT_PYTHON_PATH` and `FORMANT_AGENT_PYTHON3_PATH` to the desired values in `/var/lib/formant/.bashrc` to specify the pythons the formant user will use. These values default to `python` and `python3`.

## How can I source a custom script before the Formant agent process starts?

For native installations, export the `SOURCE_SCRIPT` environment variable in `/var/lib/formant/.bashrc` to the location of the custom script. The "formant" user will source the provided script before executing the Formant agent process. See [Environment variables for the agent](https://docs.formant.io/docs/environment-variables-reference).

## What environment variables can I add to /var/lib/formant/.bashrc?

A list of all optional environment variables that affect the behavior of the Formant agent can be found [here](https://docs.formant.io/docs/environment-variables-for-the-agent)

> 📘 Restart agent
>
> Please make sure to restart the agent (systemctl restart formant-agent) for the environment variables to take effect

## Agent setup troubleshooting

### The Formant agent ROS bridge is not running

Most parts of the formant agent ROS bridge are python3 processes. Try running import rospy in a python3 shell. If this import errors, you may have to install python3-roskpg-modules:

apt install python3-rospkg-modules

Please make sure you have the following packages installed on pyhton3 for ros\_bridge:

rosgraph\
roslib\
rostopic\
std\_msgs\
GTK\
gi\
sensor\_msgs\
genpy\
actionlib\_msgs\
geometry\_msgs\
sensor\_msgs\
The following packages need to be installed on python2 for tf2\_bridge:

rosgraph\
rospy\
tf2\_ros\
genpy

### ImportError: cannot import name Gst, introspection typelib not found

Some systems will not have a video streaming dependency installed. To fix, you can install the following:

apt install gir1.2-gst-rtsp-server-1.0

### /usr/sbin/policy-rc.d returned 101, not running 'enable formant-agent.service'

The system's policy-rd.d may be set up to disallow enabling services. Edit /usr/sbin/policy-rc.d to exit 0 instead of 101.

### ROS data not showing up on webapp

If the installation was successful, but the ROS based data is not displaying on the webapp, it is likely that the agent did not detect that it was ROS based device. Check if ROS\_MASTER is set in your environment. If it is not set, then set it as follows:

```shell
export ROS_MASTER_URI=http://localhost:11311
```

Then rerun the agent installation command you ran without the token. If you ran the docker based agent installation, rerun the docker based command.