The extension M4V denotes MP4 files containing only video streams.
The MPEG-4 Part 14 or MP4 format, which is marked by the extension mp4 as avi and mov a container format. It is based on Apple Quicktime.
The video streams may be encoded in various compression methods.
Supported MPEG 1, 2 and 4. MPEG 4 contains such codecs as Xvid, Divx and H264 and is mostly used.
mp4 files can also contain additional metadata.
The contents of the file may also be protected by DRM (Digital Rights Management). Then you need a corresponding, possibly paid license to view the content.
For mp4 files that contain only one type of data, other endings are also in use. M4a for audio, m4b for audiobooks.
Most often resolving problems with opening M4V files is very simple. Just install an appropriate program that supports such files. All of the listed programs support M4V files, but may vary in offered function and purpose. Some programs may be capable only of viewing contents of M4V files or offer file conversion options, but may not be capable of editing such files.
It is possible that although a compatible program has been installed on user’s system, it is not used by the system to open it. This may happen because no default application was associated with this type of files. To associate M4V files with given application, select "Open with" from drop-down menu (accessed by right-clicking on the file). Then select from the list the program or application you want to be used to open this type of file. If the iTunes applications is not on the list, select "Browse" option in order to manually locate the directory where iTunes has been installed.
Sometimes problems with opening M4V files may not lie with the application itself, but can arise due to other causes, such as: