To work around compatibility and file-size problems, you can reformat MP4 files using video editing and converting software. The MP4 file container, created by the Moving Picture Experts Group, supports versatile media codecs and compression techniques that support a range of video quality and type needs. However, one MP4 file might work great on one device and not on another: the incompatibility might stem from limited codec support or the video being formatted in a counterintuitive method for the specific device.

Video Editing and Converting Software

Professional video editing software like Final Cut, EDIUS and Adobe Premiere can take existing MP4 videos and export them under a different format. Free video conversion programs like Format Factory, Any Video Converter and Prism Video Converter can import any MP4 video file and convert it into another format. The program imports the existing MP4 file, and then creates a new file with the same content that uses a different format. Video editing software, however, can manipulate the video content, whereas conversion software only changes things like the compression codecs, resolution, data quality rate and container type. Note that a video editing or converting program can change the presentation style and quality of the MP4 during the reformatting process.

Converting Within MP4

MP4 is a container file -- it is not a specific type of video or audio compression. MP4 files may use the DivX, XviD, h263+ and h.264 formats for video compression. A program can convert the video between the supported MP4 types and keep the file as an MP4. However, you can use video conversion within the MP4 container type to work around device storage and screen size limitations. For example, a high-bitrate 720p MP4 might look great on a large television, but the same file can take several gigabytes and quickly use up a smartphone's storage space. In such a case, you could reformat the larger video file within the MP4 container with a 480p resolution and half the bitrate to cut the file size in half, while still keeping acceptable video quality on a phone.

Switching the Container

While the MP4 format was designed as a single standard for all device types, some playback devices are incompatible with the container, in which case you can reformat the video within a different container under a different codec. For example, you can use an editing or converting program to reformat an MP4 as an MPEG-2 in order to make it play back on a DVD player that's older than the MP4 standard. Other video codecs outside of the MP4 container include Windows Media Video and Real Media.

Video and Audio are Separate

MP4 files store the audio and video tracks separately from each other, so you can convert one without affecting the other if, for example, your playback device has trouble with Advanced Audio Coding or MP3 audio tracks, resulting in no audio playback. The editing or converting program can also set the audio track codec within an MP4 and reformat it independently of the video in a new container file.