Supported video formats include FLV and (with player release 3) H.264 encoded files. It's also possible to use image sequences together with MP3 audio to provide optimized 'video' that will load better within an editing environment. This makes navigating through the timeline much faster since only single frames (and no soundtracks) are loaded as the user scrubs through areas of the mash.

All the video formats can also be used for audio files, but MP3 offers much faster seek times. Audio files can optionally have a waveform graphic that provides a visual representation of the track in the timeline, making it easier to sync with other tracks. If specified, this graphic should have a transparent background since it's possible to overlap soundtracks in the timeline using transitions. The maximum width and height of the image is 2880 pixels.

Supported image formats include JPEG, GIF, PNG and SWF. JPEG images will usually provide better quality in smaller files, except for flat illustrations which might perform better in one of the palette or vector based formats. These can also include transparency masks which are helpful for compositing logos and animations.

Since URLs to media files are specified in the configuration, most file organizational structures are supported. The only requirement is for all the files that make up an image sequence to be in the same directory. The example implementations that come with Movie Masher also put soundracks and waveform graphics in there as well, to keep all the files that make up a video in one place. Learn more in media.