4. Offline Mode Pro

Offline Mode lets you open a previously captured DDS recording and inspect it inside the monitor exactly as if it were a live session, but with full playback control over the recorded timeline. Instead of connecting to a running DDS network, the monitor reads samples from a recording file and lets you scrub, play, pause, loop, and change speed through the captured data.

4.1. Opening a Recording

Use File → Open Recording… to select a recording file. Two formats are supported:

  • MCAP (.mcap).

  • SQLite (.db).

While a recording is open, the window title shows DDS Monitor Pro | Offline: <filename> and a playback bar appears at the bottom of the window.

Opening a recording never interrupts a live session. If the current window has never started a monitor, the recording opens in that same window. If a monitor has already been started in it (whether still active or since stopped), the recording instead opens in a new, independent monitor application, leaving the original live monitor running untouched. The two applications are separate processes, so you can inspect the recording and keep monitoring at the same time, and closing one does not close the other.

4.2. Selecting a Range

When a recording opens, a Select recording range dialog appears once so you can restrict playback to a portion of the recording. It offers a range slider (in seconds from the recording start), decimal-second spin boxes, and absolute wall-clock fields (YYYY-MM-DD HH:MM:SS, the date being optional).

  • Apply range commits the selected range.

  • Use full recording (or pressing Escape / closing the dialog) loads the entire recording.

4.3. The Playback Bar

The playback bar is only visible in offline mode and provides the following controls.

Recording information (left)

A RECORDING label, the recording file name (hover to see the full path), and the recording’s absolute start time and total duration.

Timeline (center)

A scrubber showing the current position (MM:SS) and the recording length. Drag the scrubber to move the playback cursor; hovering shows the absolute time at that point. Below the scrubber:

  • Jump to start - moves the cursor to the beginning.

  • Back 5 seconds (-5s) and Forward 5 seconds (+5s).

  • A round play / pause button.

  • A loop toggle - repeats playback continuously; the tooltip reads Looping on when active.

Speed (right)

A SPEED control showing the current playback rate. Click it to choose from 0.1x, 0.25x, 0.5x, 1x, 2x, 4x, and 8x.

A Help button opens a contextual help panel with a link to this documentation page.

You can also move the playback cursor directly on a recording chart: left-drag on the plot to move the cursor, and right-click to read the nearest point’s value. On Topic Charts, each series’ value at the cursor position is shown next to its entry in the chart legend, so the legend reads out the value of every series at the current playback point as you scrub.

4.4. What Works Offline

Charts show the whole recording at once. Spy and image panes show the last sample at or before the playback cursor (and appear empty before the first sample arrives). The following panes and panels are available offline: Topic Charts, Spy Topic Views, Topic Type Views (IDL), Image Panes, and the Register Type View.

The following are not available while inspecting a recording, and their controls are disabled with the tooltip Unavailable in offline mode (inspecting a recording):