H264LevelEditor is a small utility to edit an H264/AVC encoded video stream and change profile level. Works on both MKV container and raw streams (*.h264, *.264, *.ts or any other file containing H264 encoded video).Video stream/file is edited in-place, so it's really fast. .NET Framework 2.0 or newer required.

Authors site (support): http://coolsoft.altervista.org/h264leveleditor
Download (windows): http://www.videohelp.com/download/H264LevelEditor_1.1.0.zip