MP4XtraAtomRemover is a Windows freeware that can be used to recover some corrupted MP4 video files. It targets a specific kind of corruption that may happen on Windows: A field called "Xtra: WM/MediaClassPrimaryID" is mistakenly added to the header of the MP4 file and this is blocking the display of the video, whatever the player you use. MP4XtraAtomRemover will parse the MP4 file, locate this "Xtra" field and remove it, which will allow you to play the video again. The processing is done on a copy of the source file so your source file cannot be damaged (It will not be modified). This program will only fix the issue in the Header of the MP4 file. The Audio and Video data are not modified so there cannot be lost of quality or AV-Sync problems.