MP4Tools already includes all video encoders and decoders, you don't need to download any other codecs to make it work.
MP4TOOLS FOR PC MP4
With MP4Joiner you can join multiple MP4 files and save it to a new file without converting (encoding) so it does not degrade the original quality of your video. After a file is edited and saved, it retains its original format. Video can be split accurately by setting start point and end point, without having to re-encode the video, so no quality is lost. MP4Tools is a collection of cross-platform free tools to manipulate MP4 files. They do for Matroska what the OGMtools do for. MP4Splitter is a simple video editor that enables you to split your Mp4 video files into smaller pieces. MKVToolnix is a set of tools to create, alter and inspect Matroska files under Linux, other Unices and Windows. (Actually, the main difference between the two is that MP4Tools creates / changes. Its brother, MKVTools, has the same user interface and very similar capabilities. Also, it means that you do not need a powerful and expensive computer to edit your video material. MP4Tools is one of the video handler apps I recommend the most for, among other things, remuxing MKVs to MP4s, joining more than one MP4s into just one target MP4 and the like. This puts ''MP4Tools'' in the category of lossless video editors. This is why the editing process is very quick and does not lead to any loss of video quality. None of the editing operations in MP4Tools requires re-encoding of video or audio streams and does not require time consuming encoding/decoding operations. MP4Tools is a software pack that consists of two separate applications (MP4Joiner / MP4Splitter) designed to help you split MP4 files or merge MP4 videos.