AVI (Audio Video Interleaved) video format is common format around internet. This format was created by Windows in 1992. AVI files carry audio and video data that are played synchronously. Audio and video can be compressed with different codecs and stored in single avi file. that can be played with window played or other player with right codecs. If you are MAC used and carry iPad around you probably noticed that there is a problem with playing AVI files on these devices. Apple is stuck to MP4 format which actually is more advanced because it can carry more information that audio and video. 3D graphics, subtitles and still images also can be packed along in single file. All benefits and disadvantages you may find in internet.
User may find a problem playing one or another format on his machine. As we mentioned, without special apps there can be problem playing avi files on ipad. Instead of struggling to find one good avi player probably it is worth converting them to mp4. There are many video converters available to download. For instance Aimersoft.com produces really good free video converter called Video Converter Ultimate. It supports all common video formats like WMV, AVI, MKV, MP4, MOV including 3D and HD formats. With this converter any converted video plays on iPhones, iPads, PSP and other devices without problem. Besides this converter also gives ability to so some basic video editing like cropping, trimming frames of video. You may add visual effects, watermarks, subtitles if needed. And finally it allows merging several videos in to one single video file. Video Converter Ultimate is available for Windows and MAC users.