pauseRecording

Pause recording live topic data from ROS 2 network without closing bag writer

Since R2026a

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    Syntax

    pauseRecording(bagrecorder)

    Description

    pauseRecording(bagrecorder) temporarily halts the recording of messages from ROS 2 topics. When paused, the recorder stops capturing and writing incoming messages to the bag file, but the bag writer remains open and inactive. This functionality allows you to quickly resume recording without the overhead of reopening or reinitializing the writer.

    example

    Examples

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    Open Live Script

    Start, pause, resume, and stop a recording session dynamically while messages are being published from multiple data sources. The publishing continues uninterrupted, and you can control recording manually or based on external conditions.

    Create a node for a vehicle system that publishes telemetry, camera, and lidar data.

    vehicleNode = ros2node('/VehicleNode');
telemetryPub = ros2publisher(vehicleNode,'/car_telemetry','std_msgs/String');
cameraPub    = ros2publisher(vehicleNode,'/car_camera_feed','sensor_msgs/Image');
temperaturePub     = ros2publisher(vehicleNode,'/temperature','sensor_msgs/Temperature');

    By default, the recorder captures all topics. In this example, you record topics using IncludeRegex and ExcludeTopics filters. It includes all topics matching /car* but excludes the back camera feed.

    bagName = "DynamicRecordingBag" + string(datetime("now",Format="_yyyyMMdd_HHmmss"));
recorder = ros2bagrecorder(bagName);

startRecording(recorder,IncludeRegex='/car*',ExcludeTopics='/car_camera_feed');
disp("Recording started.");
    Recording started.

    Set up message structures for telemetry, camera, and temperature data.

    % Set up for callback structure
pubStruct.telemetryPub = telemetryPub;
pubStruct.cameraPub = cameraPub;
pubStruct.temperaturePub = temperaturePub;

% Set up for sample image message structure
telemetryMsg = ros2message(telemetryPub);
temperatureMsg = ros2message(temperaturePub);
imageMsg = ros2message(cameraPub);
imageMsg.height = uint32(480);
imageMsg.width = uint32(640);
imageMsg.step = uint32(imageMsg.width * 3); 
imageMsg.encoding = 'rgb8';

pubStruct.telemetryMsg = telemetryMsg;
pubStruct.imageMsg = imageMsg;
pubStruct.temperatureMsg = temperatureMsg;

    Publishing continues regardless of the recording state. The callback function sends telemetry, camera, and temperature messages at regular intervals until all messages are published or the script ends.

    function publishCallback(timerObj, pubStruct)
    idx = timerObj.UserData.idx;
    totalMsgs = timerObj.UserData.totalMsgs;

    if idx <= totalMsgs
        % Telemetry
        pubStruct.telemetryMsg.data = sprintf('Telemetry data message %d', idx);
        send(pubStruct.telemetryPub, pubStruct.telemetryMsg);

        % Back Camera
        pubStruct.imageMsg.data = randi([0 255], pubStruct.imageMsg.height, pubStruct.imageMsg.width, 3, 'uint8');
        send(pubStruct.cameraPub, pubStruct.imageMsg);

        % Temperature
        pubStruct.temperatureMsg.temperature = randi([0 100]);
        send(pubStruct.temperaturePub, pubStruct.temperatureMsg);

        timerObj.UserData.idx = idx + 1;
    else
        stop(timerObj);
    end
end

    Create and start a timer to publish messages at a fixed rate.

    timerObj = timer('ExecutionMode','fixedRate','Period',0.5,...
    'TimerFcn', @(timerObj,~)publishCallback(timerObj,pubStruct));
timerObj.UserData.idx = 1;
timerObj.UserData.totalMsgs = 2000;
start(timerObj);

    You can pause, resume, or stop recording manually at any time or based on external conditions. These options enable you to control the recording during a live session.

    pauseRecording(recorder);
disp("Paused recording");
    Paused recording

    resumeRecording(recorder);
disp("Resumed recording");
    Resumed recording

    stopRecording(recorder);
disp("Recording stopped.")
    Recording stopped.

    After stopping the recording, inspect the recorded topics and message types.

    bagReader = ros2bagreader(bagName);
disp(bagReader.AvailableTopics(:,1:2))
                          NumMessages      MessageType  
                      ___________    _______________

    /car_telemetry         1         std_msgs/String

    You can see that messages published when the recording was active are stored in the bag file, while those published when the recording was paused are not recorded.

    Input Arguments

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    ROS 2 bag recorder, specified as a ros2bagrecorder object.

    Example:

    Version History

    Introduced in R2026a

    See Also

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