What is VOD?
VOD (video on demand) streaming uses a multimedia file as the source; it is always accessible; it always plays from the beginning or other specified start point, and it has a duration (which is usually included in the file’s metadata). By comparison, a live stream is always playing in progress, is only available while it is live, and has an unknown duration.
For all playback client types, Wowza Streaming Engine™ software supports on-demand play of .mp4 and other QuickTime container files (.mov, f4m, .3gpp, etc.) that contain H.264 video and AAC or MP3 audio. For Flash RTMP and Flash HTTP clients, Wowza supports play of .flv files that contain SorensonSpark or VP6 video and NellyMoser or Speex audio.
It is important in streaming to know the bitrate of a file used for on-demand streaming. The approximate average bitrate of a file can be calculated by using this formula: size in bytes * 8 / duration = bits per second (bps).