Apple's HTTP Live Streaming system avoids the need for specialized streaming servers by using standard HTTP to deliver video streams. It has four main components: a server that encodes and segments the video into small clips; a segmenter that stores the clips as separate files and creates an index file; a regular HTTP server that distributes the files; and a client that retrieves the files and continuously refreshes the index to receive a live, moving window of video segments or access all segments for video on demand. The system supports delivering multiple bitrate streams to different devices by providing multiple index files that clients can select from.

1. Apple’s HTTP Live Streaming

2. Agenda System Overview Components Session

3. Apple’s Note Note: Many existing streaming services require specialized servers to distribute content to end users. It requires specialized skills to set up and maintain these servers, and in a large-scale deployment these servers can be costly. Apple has designed a system that avoids this by using standard HTTP to deliver the streams.

4. System Overview

5. Components Review Server Encoder Segmenter Distributer Basic HTTP Server Client

6. Server Receives Digital / Analog input stream Encodes / Transcode video/audio H.264 Video AAC audio (HE-AAC or AAC-LC) Encodes / Transcode audio only: MPEG-2 elementary streams, HE-AAC or AAC-LC files, or MP3 files Encapsulate in MPEG2 Transport Stream Program Stream

7. Segmenter All segments should be with the same duration All segments are placed in a separate file Creates Index file with references to segment files For protection, the Segmenter might encrypt each media segment and create a key file

8. Distribution Distribution system is a regular HTTP Server Could be Apache or small embedded Server

9. Files Segments – stored as *.ts files Index files – stored as *.m3u8 Index file format example: #EXTM3U #EXT-X-TARGETDURATION:10 #EXTINF:10, http://media.example.com/segment1.ts #EXTINF:10, http://media.example.com/segment2.ts #EXTINF:10, http://media.example.com/segment3.ts #EXT-X-ENDLIST

10. Session types Live Stream Broadcast Index file is continues updated Include a moving window of segments around “live” part of the session Client should continuously refresh the Index file VoD Session Index file static Includes ALL the segments of the file Enables “Seek” operation

11. Multi-bitrate multi–device support Multi-bitrate is enabled via multiple index files Index files are pointed by a global index files Client can select a stream according to: Device properties Available bit rate This method is less efficient than Silverlight Global File

12. Test yourself What are the two Live streaming file types? What is the role of the Segmenter? On which delivery protocol is the live streaming based?

13. DSP-IP Contact information For Course materials licensing & lecture request contact: For projects development services contact: Adi Yakov Training and Courses Manager [email_address] +972-9-8651933 www.dsp-ip.com Mail : [email_address] Phone: +972-9-8850956, Fax : +972-50- 8962910 Alona Ashkenazi Technology Management Services : [email_address] +972-9-8850956