The H264LevelEditor application was developed to be a free and small tool to edit an H264 / AVC encoded video stream and change IDC profile level. Works both on MKV containers and raw H264 streams (.h264, .264, .ts or any other file containing H264 encoded video).
 
Video stream/file is edited in-place, which means:
fast editing
no need to reencode the file (save time)
no need to demux, edit and remux streams (save time and HDD space)
To make a long story short, some mediaplayers look the video file being played for an header info name AVC profile level; if this level is greatest than a supported one they simply refuse to play it, even if they could.
BluRay specifications requires level 4.1, which is supported by all actual HD mediaplayers. Many of the video files you'll find on internet were encoded with an unnecessary high level, like 5.1.
The right way to change AVC level is to re-encode the file; this is really time consuming, even if you have a recent CPU. A quick way is to change some bytes inside the file and make it appear as being encoded with a different level; if you're lucky, changing that 5.1 to 4.1 will make the file playable on your mediaplayer. If this in-place editing won't work, your last (and only) resource is to re-encode the whole file.
Using H264LevelEditor is easy as 1-2-3:
- select the video file to edit by pressing then tree-dots button, or drag&drop the file directly from Windows Explorer
- H264LevelEditor will show actual AVC level into the "h264 level" box, choose the new level you want to set
- press "Change level" button

Requirements:
· NET Framework 2.0 or newer is required to run this tool