purpose of "re-enable the stream for the change to take effect"

[christian-rauch]

During the launch of the realsense2_camera_node with a custom configuration, I see

re-enable the stream for the change to take effect.

twice in my screen logs. I am manually setting the color_profile and depth_profile to 640x480x60 each.

I assume this message is shown since the camera's default 1280x720x30 and 848x480x30 respectively is changed to 640x480x60.

From the message itself, it is not really clear how this is caused and what the effect of not "re-enable the stream" will be.

Starting the node with a custom color_profile:

ros2 run realsense2_camera realsense2_camera_node --ros-args -p rgb_camera.color_profile:="640x480x60"

shows the re-enable the stream for the change to take effect. message.

However, inspecting the parameter (ros2 param get /camera/camera rgb_camera.color_profile) and the topic (ros2 topic echo --no-arr /camera/camera/color/image_raw) shows me that the parameter is set (String value is: 640x480x60) and that the image has the expected dimension:

height: 480
width: 640
encoding: rgb8
is_bigendian: 0
step: 1920
data: '<sequence type: uint8, length: 921600>'

So, what is the purpose of this warning? And, if it is important to "re-enable the stream", why is this not done automatically?

[MartyG-RealSense]

Hi @christian-rauch Typically, in the ROS2 launch log the message re-enable the stream for the change to take effect is followed by messages such as these:

Stopping Sensor: Stereo Module
Starting Sensor: Stereo Module

Stopping Sensor: RGB Camera
Starting Sensor: RGB Camera

So the launch is automatically stopping and then re-starting sensors in order to apply the change. You do not need to take any action.

[christian-rauch]

Indeed, I see this in the full log:

re-enable the stream for the change to take effect.
Stopping Sensor: Depth Module
Stopping Sensor: RGB Camera
Stopping Sensor: Motion Module
Starting Sensor: Depth Module
Open profile: stream_type: Infra(1), Format: Y8, Width: 848, Height: 480, FPS: 30
Open profile: stream_type: Infra(2), Format: Y8, Width: 848, Height: 480, FPS: 30
Open profile: stream_type: Depth(0), Format: Z16, Width: 848, Height: 480, FPS: 30
Starting Sensor: RGB Camera
Open profile: stream_type: Color(0), Format: RGB8, Width: 640, Height: 480, FPS: 60

I think this is then the same for setting unite_imu_method other than 0, which will cause:

For the 'unite_imu_method' param update to take effect, re-enable either gyro or accel stream.

but also seems to be handled automatically:

Stopping Sensor: Motion Module
Stopping Sensor: Motion Module

Since I always see the Stopping / Starting messages, also with the defaults:

Stopping Sensor: Depth Module
Stopping Sensor: RGB Camera
Stopping Sensor: Motion Module
Starting Sensor: Depth Module
[...]
Starting Sensor: RGB Camera
[...]
Starting Sensor: Motion Module

it is not really clear if this is done automatically because of the warnings or if a user should still stop/starting them again manually.

I honestly find these warnings confusing as it appears the user is supposed to do something. What purpose do these warnings server if they are handled automatically? Can you just remove them?

[MartyG-RealSense]

There have not been previous requests to remove the 're-enable the stream for the change to take effect' warning message so users of the ROS wrapper seem to be okay with it. If a number of users reported that it caused confusion for them then it could certainly be looked at in future, and if any users reading this issue feel confusion about it then they are very welcome to leave a comment here.