Error in opening mp4 file

While using gaze redirect i am getting the following error when converting offline videos

ERROR: Unable to open the input video file “123.mp4”
ERROR: no video source has been found

using the following commands.

SETLOCAL
SET PATH=%PATH%;…..\samples\external\opencv\bin;…..\bin;
SET NVAR_MODEL_DIR=…..\bin\models
GazeRedirect.exe --offline_mode --split_screen_view=false --in=123.mp4