iBooks Author: supported file formats
You can add these kinds of digital files to an iBooks Author document:
Image files: JPG, JPEG, PNG, GIFNote: The recommended file format is JPG. If the image includes transparency, PNG is recommended.
Video and audio files: M4V, M4ANote: For the Media widget, you can add a video file or an audio file (in a format QuickTime supports) to your book. You can convert other types of files using iMovie, QuickTime Player, or Compressor. For the HTML widget, the suggested file formats are MP4 video files and M4A audio files.
Document files: PDF