Analyzing Videos Synchronized to Recorded Traces

Experiments with moving parts or explosions were often recorded with standard or even high-speed cameras. Video recordings help to explain or justify the data captured from various sensors and recorded with a data a cquisition system like Elsys's TraNET FE. TranAX brings together the video recording and sensor data in one program, synchronized to each other.

The new Video Window

For viewing videos inside of TranAX a new Video Display is introduced which works like a standard video player. This new display can be placed aside of other displays like Waveforms, Spectrums or Scalar tables. The video display supports the most common file formats like avi, mp4 and mpg. In addition to a standard video player TranAX can play video files forward, backward or frame by frame.

TranAX Video Display

Figure 1: The new video display in TranAX

Synchronize the video to the traces

Videos, recorded simultaneously with the captured traces, can be played simultaneously, synchronized by the frame rate. During the video playback, a cursor in the waveform display indicates the corresponding time position of the video in the trace data. For correct synchronization two parameters must be correct: the frame rate of the video and a common reference or origin position.

The frame rate of standard video cameras is 25 frames per second (fps), professional high speed cameras have the ability to make videos at different and higher frame rates up to 10000 fps. This frame rate must be set correctly on the video display for having a common time axis for video and trace data.

Even if the camera shot is triggered by the data acquisition system some time delays or different pre-trigger times could be possible. For this reason a position in the video must be found which can be identified as the same position in the trace data. For example the first contact of two objects must also be visible in a force sensor signal. This reference position is set in TranAX by setting the origin point in the video display at the corresponding position and setting the "Video Origin Marker" in the waveform display.

Trace data synchronized to the video file

Figure 2: Trace data synchronized to the video file

From this point, when the video is run, the cursor is moved in the Waveform display and vice versa.