Knowledge Base

Synchronize Data Manually After Import

Aim

To adjust the offset between external data and video/track data.

Note: You change the offset of the original signal. The offset is automatically applied to all the EthoVision XT variables derived from that signal. Choose Analysis > Results > Integrated Visualization.

Procedure

1. From the lists available on the toolbar, choose the Track smoothing profile, the Data profile, the Analysis profile and the trial to visualize.
   • Make sure that the signals are well visible; zoom in/out if necessary.
   • If you want to re-synchronize using an event visible in a specific video frame, position the video to that frame.
2. Click the External data synchronization button on the toolbar, or choose Show/Hide > External data synchronization. If no original signal is displayed in a chart, EthoVision asks you to select the original signal for synchronization. Take note of the original start and stop time in the Synchronize external data window. If you change the offset and click OK, the start/stop times are overwritten and cannot be recovered.
3. You can synchronize data in two ways:
   • In the Synchronize external data window, enter the new Start date and time and the Stop date and time for the chosen signal.
   • In the plot area, hover the mouse over the original signal and drag to the position you require. While you drag the mouse, the time plot of the original signal is shifted to the left or to the right. The Synchronize external data window shows the new Start and Stop time of the original signal. Release the mouse button when ready.
4. Select the option Apply synchronization to all signals originating from the same data file if you also want to apply that offset to the EthoVision XT variables derived from the other signals imported from the same data file. Make sure to keep this option selected when you import data sets from the same data file and you want to maintain the original offset for all those data sets.
5. When ready, click OK.

Notes

• The shift in the offset is also applied to signals derived from the original signal, which are not currently visualized.
• After clicking OK, the shift in offset cannot be undone. To restore the original offset you must know the original Start and Stop time and enter them in the Synchronize external data window.
• To stretch the data in time, enter new values for Start and Stop time in such a way that the duration of the data set is longer than the original. First enter Start time, then Stop time.
• To shrink the data in time, enter new values for Start and Stop time in such a way that the duration of the data set is shorter than the original. First enter Start time, then Stop time.
• If your data plots include EthoVision XT variables derived from signals other than the one you synchronize, these are not synchronized automatically, unless the original signals come from the same file and you select Apply synchronization to all signals originating from the same data file. In all other cases, to synchronize those variables, open the signal they are derived from and repeat the procedure above for that signal.
• Re-synchronization may affect your data selection when this contains Nesting functions based on those external data. For example, your Data profile contains a Nesting function based on Temperature state, which selects the intervals when Temperature > 30 °C. If you re-synchronize Temperature and Temperature state, then also the intervals based on Temperature state will shift accordingly. Plot the data to check the changes.
• To undo the changes and return to the current offset between data sets, click Reset in the Synchronize external data window.
• If you synchronize external data at least once, re-opening the Synchronize external data window and clicking Reset does not restore the offset when you imported the data. It simply restores the last saved offset.

Other Ways to Ensure Synchronicity Between Video and Data Streams

Aim

Whenever you want to ensure high synchronicity between your video and the external data streams, for example EMG, this topic describes the possible solutions. This topic applies to Basler digital cameras.

Method 1 - Send a Signal at Every Video Frame

Many Basler digital cameras including the acA1300-60gm GigE camera have a 6-pin I/O connector on the back. Pin number 2 is for input (named Line1 in Pylon Viewer), while pin number 4 is for output (Out1 in Pylon Viewer). You can connect pin 4 to a channel of the DAQ system that reads the time that the video frame is sent out.

Note: Which pin number serves a specific function may vary depending on the camera model. Please refer to the camera documentation.

1. Set the camera for example to free-running at 60 fps and get an electrical signal on the camera output Out1 pin when the camera makes a new frame. Settings can be made using the Pylon Viewer application. For details, see the Pylon Viewer manual and the camera manual.
2. Connect the camera output to the data recording channel. This way you know down to microseconds accuracy when the camera creates a video frame.

Method 2 - Send a TTL Pulse to the DAQ System

For this you need a USB-IO box and the Trial and Hardware Control add-on module.

1. Connect a TTL port of the USB/IO box to one of the channels of the DAQ system. For this you need a cable with a RJ45 connector at the end of the USB-IO box and a connector at the other end that matches the DAQ system.
2. In the Trial Control Settings of EthoVision XT, make a sub-rule with an action on the chosen TTL port that sends a pulse of 1 second at regular intervals, for example every 5 seconds.
3. During the trial, the pulses are recorded by the DAQ systems.

For more information:

• The chapter Experiments with Calcium Imaging in the EthoVision XT 19 - Application Manual, which includes an example with the Inscopix nVoke system.
• The EthoVision XT 19 - Trial and Hardware Control - Reference Manual.

Note: To connect the camera to a DAQ system, you can use the standard cable available from Basler, or make your own using a Hirose connector HR10-7P-6S(73).