This MATLAB function loads a GUI front end for the MATLAB SyncTool functions, which allows to synchronize multimodal recordings of signals with SMPTE Time Code. Therefore you need to download the SyncTool functions and add them to a directory that Matlab can search, as well as Python and FFmpeg. The SyncToolGUI loads an XML file created by the XML Creator which has a defined SIEMPRE experiment. The SyncToolGUI parses the XML code and searches for any data that has been tagged with the appropriate keywords (see the SyncToolGUI main help file for a full description of the group and sensor keywords). The user then needs to set the input file names for each of the data types (a number of macros have been added to help with this – again see the main help file for a full description of the macros) in addition to providing the GUI with the file path of a file containing the SMPTE cut times for each take. When the user has entered all the relevant information they can they hit the Perform Sync button which will load and validate all the data the user wants the GUI to sync, and pass this data to the relevant sync tool functions. The synced data can then either be exported to a Matlab variable or it can be exported to the SIEMPRE broadcast wave format (see the main help file for more information on this).