Console App

MP4 Repair Tool - Windows 7

This MP4 Repair tool is for MP4 video files that stopped playing after being moved to a different folder on Windows 7.  
215 byte structure

I have found a few other utilities that repair MP4 files but have had little luck.  After finally reproducing this it looks like the service Windows Media Player Network Sharing Service is modifying MP4 files when they are moved.  As far as I've researched this is a Windows 7 only problem and does not happen on Windows 8 or 10.

Multiple changes were made to the file however a 215 byte chunk was added with the header 4meta.  This tool searches the specified MP4 file for the header "4meta" and if found, removes the 215 bytes of data. 

With this 215 bytes removed the file is once again playable in Media Player Classic.

Flow of the program:  Parses arguments.  If argument one is a file, it is opened and the program begins scanning for '4meta'.  If not found it is stated and program quits.  If found the program asks you if you want to make a backup of the file.  Selecting yes copies your file with the words "backup of" in front of it in the same folder as your mp4 file.  Bytes written are displayed.  Then the program asks you if you want to remove the 4meta tag.  If yes, the program bulk copies from position 0 to 1 byte before the start of 4meta tag to file $tempmp4.mp4, and then continues copying 215 bytes after the start of 4meta tag to the end of the file.  Both file handles are closed, original file is deleted, $tempmp4.mp4 is renamed to your original file.

MP4 Repair

This tool has proved effective in reviving my MP4 files on Windows 7.  Use with caution and make sure you make a backup.  Reading from one directory and saving to another is not supported as this tool is made to be simple as possible.  Source code, 32-bit and 64 bit executables are included.  Build on Lazarus / Free Pascal.

No support offered.

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