Instant Replay

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The instant replay dialog.

FlightGear 2024.1 and later support three forms of flight recordings:

  • Restricted Normal (memory-based) recordings.
  • Unlimited Continuous (disk-based) recordings.
  • Single-frame recovery snapshots.

Recording and replaying is controlled by the Main Menu > File > Flight Recorder Control dialog.

Normal (memory-based) recordings

FlightGear always maintains an in-memory "Normal" recording of the current session. To avoid running our of memory, only the last minute or so is recorded in full detail, and older data is gradually pruned.

The in-memory recording can be saved to a file.

Starting and controlling replay of normal recording

  • Press Ctrl-r or select Instant Replay from the View menu to start the replay. Replay starts immediately.
  • Press p or click pause to pause/resume the replay.
  • Use the left/right arrow keys, or the <<, >> buttons to skip. You can also use the mouse and drag the time slider.
  • Use the up/down arrow keys, or the +, - buttons to change replay speed. You can replay at slow-motion, real-time or fast-forward speed.
  • Enable the Loop checkbox to continuously repeat the playback. When you configure a duration (in seconds) then only the last few seconds are continuously replayed.

Stopping replay

  • Press Escape or the End Replay button to stop replay and return to the position prior to starting replay.
  • Alternatively, click the My Controls! button to take over control at any point. With this feature you can use the replay system to go back in time, regain control and then continue the flight from a past position. This is useful to train particular flight phases, such as flying the same approach again and again, maybe using different weather/wind conditions.

Continuous (disk-based) recordings

Continuous recording writes directly to a file without any loss of detail.

Optionally record/replay extra information

  • Multiplayer aircraft.
  • Main window size.
  • Main window position.
  • Main window view.

Aircraft override

  • When loading a Continuous recording at startup, we override the aircraft and starting airport to match what is in the recording.

Replay directly from local file or URL on startup

  • Specify a local file with the --load-tape command-line option, for example: --load-tape=harrier-gr3-20211107-162046-continuous.
  • Specify a URL with the --load-tape command-line option, for example: --load-tape=http://foo.com/bar.fgtape.
The Flight Recorder Control dialog.

In both cases, Flightgear will use the recording's aircraft type, overriding any specified or default aircraft.

Recovery snapshots

Recovery snapshots are periodic single-frame continuout recordings, and for some of the simpler aircraft, they allow resumption of a flight after a FlightGear crash.

Details

Continuous recordings

  • Continuous recording to file uncompressed is e.g. 100MB for an hour's recording near EDDF.
  • Support for compression of Continuous recordings was pushed to next on 2021-7-31 (FlightGear commit 7d41488).
  • Replay of Continuous recordings from URL:
    • Downloads to local file in the background while replaying.
    • Reuses local file if present, appending to it in the background if it was a partial download.
    • Local file is in directory specified by property /sim/replay/tape-directory.

Recovery snapshots

A recovery snapshot is actually a single-frame continuous recording, and will be called <aircraft-type>-recovery.fgtape.

  • Load on the command line with --load-tape=<aircraft-type>-recovery.
  • Then do Ctrl-R to see the replay dialogue.
  • And click on My Controls.
  • Notes:
    • Some aircraft do not support My Controls.
    • Loading a recovery file from within Flightgear via the Flight Recorder Control dialogue is usually not useful because the recovery file will have been overwritten by the current Flightgear session.

File formats

For details on recording file formats, see: flightgear/docs-mini/README-recordings.md

Related content

Wiki articles

Forum topics

Readme file

Source code

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