Helpful definitions for Apple Live Streaming

File Type Description Extension Example
Variant Playlist The player requests this file just once at the start of the session. It contains a list of all the requested stream’s available bit rates (tracks). Since the file includes each track’s bandwidth, the player uses this bandwidth information to switch between the most appropriate bit rates in case of network bandwidth fluctuations. m3u8 master.m3u8
Child Playlist Each track has its own child playlist file that contains a list of segments available for playback. The number of segments in the file determines how far back the player can seek from the live point.

For a live stream, the player requests this file frequently to get the next set of segments for playback. The encoder includes an end-of-stream marker to indicate the stream’s end has been reached. When the player receives this marker, it stops requesting the file and also stops playback (after running through its buffer).

m3u8 index_1000kpbs. m3u8
Segment This file contains the video and/or audio data in MPEG2-TS format. For audio-only tracks, the data is in the AAC format with a .aac extension. ts / aac segment10.ts
Encryption Key This file includes a 128-bit key used to encrypt the segments. It is only requested when encryption is turned on at the encoder. key crypt.key