gscam2

ROS2 port of gscam. Supports ROS2 intra-process comms.

Update 15-Jun-22: gscam has been released for ROS2. It does not support IPC.

Update 16-Mar-21: the package name has been updated to match the repository name (gscam2)

Install and build

Tested on ROS2 Foxy, Galactic, Humble and Rolling. See the Dockerfile for install and build instructions.

Usage

Make sure your GStreamer pipeline runs successfully in gst-launch-1.0. For example, here's a pipeline that works for the Blue Robotics HD USB Camera: ~~~ gst-launch-1.0 -v v4l2src device=/dev/video1 do-timestamp=true ! queue ! video/x-h264,width=1920,height=1080,framerate=30/1 ! h264parse ! queue ! avdec_h264 ! autovideosink ~~~

Here's the same pipeline in gscam2: ~~~ export GSCAMCONFIG="v4l2src device=/dev/video1 do-timestamp=true ! queue ! video/x-h264,width=1920,height=1080,framerate=30/1 ! h264parse ! avdech264 ! videoconvert" ros2 run gscam2 gscam_main ~~~

Here's an example with parameters: ~~~ ros2 run gscam2 gscammain --ros-args --remap /imageraw:=/mycamera/imageraw --params-file gscamparams.yaml -p camerainfourl:=file://$PWD/mycamerainfo.ini ~~~ ... where gscamparams.yaml is: ~~~ gscampublisher: rosparameters: gscamconfig: 'v4l2src device=/dev/video1 do-timestamp=true ! queue ! video/x-h264,width=1920,height=1080,framerate=30/1 ! h264parse ! avdech264 ! videoconvert' preroll: True usegsttimestamps: True cameraname: 'mycamera' frameid: 'mycameraframe' ~~~

Here's an example that uses a GStreamer tee to split the stream, with one stream producing ROS images and the second stream writing to MP4 files: ~~~ export GSCAMCONFIG="v4l2src device=/dev/video1 do-timestamp=true ! queue ! video/x-h264,width=1920,height=1080,framerate=30/1 ! h264parse ! tee name=fork ! queue ! splitmuxsink location=video%02d.mov max-size-bytes=10000000 fork. ! avdech264 ! videoconvert" ros2 run gscam2 gscam_main ~~~ There's a bug where the last MP4 file is not closed correctly.

Intra-process comms

IPC test -- CLI composition: ~~~

First shell

ros2 run rclcppcomponents componentcontainer

Second shell (ignore the deprecation warning, see https://github.com/ros2/ros2cli/issues/336)

ros2 component load /ComponentManager gscam2 gscam2::ImageSubscriberNode -e useintraprocesscomms:=true ros2 component load /ComponentManager gscam2 gscam2::GSCamNode -e useintraprocesscomms:=true ~~~

Launch file composition: ~~~ ros2 launch gscam2 composition_launch.py ~~~

Manual composition -- handy for debugging: ~~~ ros2 run gscam2 ipctestmain ~~~

Finding GStreamer plugins

GStreamer scans various paths for plugins and builds a plugin registry. The search process is described here.

gscam uses a parameter gst_plugin_path instead than the commandline option --gst-plugin-path. The paths in gst_plugin_path are searched last, not first.

If you have custom plugins you may need to override the plugin path. Here's an example showing how this works: ~~~

Disable default locations

export GSTPLUGINPATH="" export GSTPLUGINSYSTEM_PATH=""

Provide the pipeline configuration

export GSCAM_CONFIG=videotestsrc pattern=snow ! video/x-raw,width=1280,height=720 ! videoconvert

Run gscam_main, providing a custom plugin path

ros2 run gscam2 gscammain --ros-args -p gstplugin_path:="/home/me/myplugins" ~~~

Parameters

| Parameter | Type | Default | Notes | |---|---|---|---| | gst_plugin_path | string | | Similar to --gst-plugin-path, searchs path for plugins | | gscam_config | string | | GStreamer pipeline configuration | | sync_sink | bool | True | Enable GstBaseSink synchronization | | preroll | bool | False | Transition to GSTSTATEPLAYING twice | | use_gst_timestamps | bool | False | Use gst time instead of ROS time | | image_encoding | string | sensor_msgs::image_encodings::RGB8 | ROS image encoding | | camera_info_url | string | | URL to camera info file, e.g., file:///path/to/file | | camera_name | string | | Replaces ${NAME} in the URL | | frame_id | string | camera_frame | Camera frame ID |

Topics

• camera_info
• image_raw
• image_raw/compressed - only if image is encoded as a jpeg stream

Camera info file formats

Uses the ROS standard camera calibration formats. Files must end in .ini or .yaml.