Video overlay

From edgertronic high speed video camera
Revision as of 18:31, 4 April 2016 by Tfischer (talk | contribs) (Notes parameters)
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Anticipated release: 2.2

Video overlay has not been released yet.


The edgertronic camera supports modifying the pixels in each video frame to overlay text and graphics. The video frames with the overlay applied are then encoded into a video file. To keep from obscuring the captured video, a black border can be added to the bottom of each video frame with the overlay being displayed in the black border region.

There are different overlay features that can be individually enabled or disabled:

  • Adding a black border to the bottom of each frame
  • Overlay frame number
  • Overlay notes text with parameter expansion
  • Overlay settings
  • Overlay logo


The Overlay tab in the Settings modal allows on/off setting for each of the 4 overlay features along with a Notes field that can contain a text string. The camera comes with pre-defined layout control for the frame number, settings, and logo. Using the web UI, you can specify the Notes text. The Notes text can contain ampersand & parameters that are expanded when the video is being saved.

Notes parameters

The following ampersand parameters can be included in the Notes text. When the file is being saved, the camera will substitute the actual value in place of the ampersand parameter. An overlay preview is displayed in the web UI for a few seconds after calibrate completes. Dummy parameter values are used during overlay preview if the actual value is not available until a video is captured.

Variable Camera Setting
&d Trigger date (DD-MMM-YY)
&t Trigger time (HH-MM-SS)
&T Trigger time (seconds since Jan 1, 1970)
&i Sensitivity (ISO)
&s Shutter
&f Frame rate
&S Sub-sampling
&o Overclock
&e Extended dynamic range
&g Genlock
&b Multishot buffer
&n Serial number
&N Name of file
&F Scaled font size
&y Camera calculated y (vertical) position


When an overlay is enabled, the live preview visible in the web UI for a few seconds after camera calibration completes. This allows you to verify the overlay layout. Some of the Notes parameters, such as trigger time, are only available when the camera is saving the video, so during overlay preview, dummy values are used.


The pipelines file contains the actual information used by GStreamer to generate the overlay. You can supply our own customized pipelines file if you want to modify the overlay.