The present invention is to provide a method to be used on an electronic device, which employs the demultiplexing process to divide the data streams from video file compatible with DVD read/write formats, or video file from several DVD disks; into several independent and separate files; the data streams include audio, video, and subtitle; subsequently, the data streams that include audio, video, and subtitle are subject to the multiplexing process in accordance with UDF 2.50 or UDF 2.60 formats, in order to combine the data streams into a new video file. In the method, because the demultiplexing process and the multiplexing process simply divides the data streams that include audio, video, and subtitles into separate files; the processes does not encode or decode these data streams, and thus the original video quality and audio quality can be preserved