563.mp4 -

If 563.mp4 is just one of many numbered files (e.g., 561, 562, 563) and you want to combine them into one long video:

If you have a file named 563.mp4 that won't play, it may be a "broken" segment from a crash. 563.mp4

If you open the file in a text editor like Notepad and see "gibberish" or specific Java/FFmpeg flags, it confirms it is a data file, not a simple document. If 563

Create a text file (e.g., file_list.txt ) listing the files in order. 563.mp4

In the context of the (Network Video Recorder), "563" often appearing near ".mp4" usually refers to a Process ID (PID) or a specific camera stream segment.