1. Streaming Media Protocols Jani Hautakorpi Henry Pohan

2. 23.3.2005T-110.4562 / N Contents Protocols and languages – Overview Session control – RTSP and SIP Media description – SDP Media transportation – RTP 3GPP Packet-Switched Streaming Service (PSS) Protocols in 3GPP PSS 3GPP PSS Domain Architecture & Framework 3GPP PSS Release 6 extensions Summary

3. 23.3.2005T-110.4563 / N Protocols and Languages – Overview Session control RTSP SIP H.323 SAP WSP Media descrip. SDP SMIL CC/PP Media transpor. RTP HTTP

4. 23.3.2005T-110.4564 / N Session Control – RTSP (1/2) Real-Time Streaming control Protocol Used in streaming communication Transaction-oriented, request-response protocol Text-based, data is carried out-of-band Messages can contain a message body Example methods: play, forward, rewind, pause, … Current development: Usage with NATs, key management extension.

5. 23.3.2005T-110.4565 / N Session Control – RTSP (2/2) Client Server SETUP 200 OK PLAY 200 OK TEARDOWN 200 OK Media Has SDP

6. 23.3.2005T-110.4566 / N Session Control – SIP (1/2) Session Initiation Protocol Mostly used with conversational media (preliminary discussion on the use with streaming media) Very popular protocol (used e.g. in IMS) Very similar to RTSP (text-based, request-response, data out-of-band) Current development: Security and privacy extension, integration with QoS mechanisms, …

7. 23.3.2005T-110.4567 / N Session Control – SIP (2/2) Initiator Responder INVITE 180 Ringing 200 OK ACK BYE 200 OK Media

8. 23.3.2005T-110.4568 / N Media Description – SDP (1/2) Session Description Protocol Widely deployed Carried as a payload of session control protocol Text-based Capability negotiation (offer/answer model) Current development: Offer/answer model, exchange of encryption keys, SDPng, …

9. 23.3.2005T-110.4569 / N Media Description – SDP (2/2) v=0 o=bill 2890844526 2890842807 IN IP4 193.34.4.2 s=Streaming media protocols i=A presentation on the media protocols u=http://www.barfoo.com/bill/media.ps e=bill@barfoo.com (Bill Huxton) c=IN IP4 193.3.44.21 t=2873397496 2873404696 a=recvonly m=audio 49170 RTP/AVP 0 m=video 51372 RTP/AVP 31 m=application 32416 udp wb a=orient:portrait Session Media

10. 23.3.2005T-110.45610 / N Media Transportation – RTP Real-time Transport Protocol Dominant streaming media transport protocol Runs usually on top of UDP Accompanied with RTCP Binary protocol Can also transport encrypted media

11. 23.3.2005T-110.45611 / N Packet-Switched Streaming Service (PSS) PSS – an umbrella standard (IETF, 3GPP, W3C, MPEG, ITU) –Signaling and control protocols (RTSP and SDP from IETF) –Transport protocols (RTP, RTCP, and various payload formats from IETF) –Audio codecs (AMR and AMR-WB from 3GPP, AAC from MPEG-4) –Visual codecs (H.263 from ITU, Simple Visual Profile from MPEG-4) –File format (MP4 file format from MPEG-4 Systems) –Scene description (SMIL from W3C) 3GPP PSS Versions: –Release 4 – 1 st version, Q1 2001 –Release 5 – Q2 2002 –Release 6 – Q3 2004

12. 23.3.2005T-110.45612 / N 3GPP PSS – Protocols

13. 23.3.2005T-110.45613 / N 3GPP PSS – Protocol Stack

14. 23.3.2005T-110.45614 / N 3GPP PSS – Domain Architecture Streaming Client & Content Server –main component Proxy Server –provide QoS streaming service User and Profile Servers –keep user preferences and device capabilities Content Cache (optional) –for improving overall service quality Portals –servers for convenient access to streamed media content SGSN –gateway betwen user equipments within its serving area (UEs) GGSN –gateway between UMTS core network and internet (IP-PDN)

15. 23.3.2005T-110.45615 / N 3GPP PSS – Domain Architecture (cont.) Internet Multimedia Subsystem (IMS) Proxy Gi

16. 23.3.2005T-110.45616 / N PDP Context Activation Procedure UE SGSN Activate PDP Context Request Security Functions RAB Assignment Request Create PDP Context Response Activate PDP Context Accept Radio Bearer GGSNUTRAN/GERAN RAB Assignment Response Create PDP Context Request

17. 23.3.2005T-110.45617 / N Streaming Multimedia Session Establishment in PSS UE Presentation and Content Server [RTSP] DESCRIBE [RTSP] 200 OK [RTSP] SET UP [RTSP] 200 OK [RTSP] PLAY [RTSP] 200 OK GGSN Primary PDP Context Activation Secondary PDP Context Activation RTP and RTCP flows

18. 23.3.2005T-110.45618 / N 3GPP PSS Release 6 Some Extensions 3GPP file format: –General profile –Progressive-download profile –Streaming server profile DRM for Streaming –Based on OMA DRM 2.0 Quality of experience –At the end of the session end user experience is reported back to the server –Metrics: rebuffering duration, initial buffering duration, successive loss of RTP packets. Adaptive Streaming –Adaptation of transmission and content rates to the available network resources Avoid network buffer overflow Avoid client buffer underflow/overflow Highes possible quality of experience –Client buffer feedback using RTCP is defined –Server centric approach (implementation specific): Estimation of available network resources Setting of transmission and content rate Interworking with charging / billing services for next 3GPP PSS release…?

19. 23.3.2005T-110.45619 / N Summary Media sessions require three components: –Session control protocol –Session description language –Media transportation protocol 3GPP PSS is standard specification at application layer that evolved from simple streaming service (Rel. 4) to more advanced one (Rel. 5 & Rel. 6) with concern in backwards compatibility.

20. 23.3.2005T-110.45620 / N References Sudhir Dixit and Tao Wu, Content Networking in The Mobile Internet H. Schulzrinne et al., Real Time Streaming Protocol (RTSP), IETF, RFC 2326, proposed standard, 1998. J. Rosenberg et al., SIP: Session Initiation Protocol, IETF, RFC3261, proposed standard, 2002. M. Handley and V. Jacobson, SDP: Session Description Protocol, IETF, RFC 2327, proposed standard, 1998. H. Schulzrinne et al., RTP: A Transport Protocol for Real-Time Applications, IETF, RFC 3550, standard, 2003. 3GPP TS 26.233 Transparent end-to-end packet switched streaming service (PSS); General description (Release 6). 3GPP TS 26.233 Transparent end-to-end packet switched streaming service (PSS); Protocols and codecs (Release 6). 3GPP TS 26.233 Transparent end-to-end packet switched streaming service (PSS); Stage 1 (Release 6). Presentation Slide from Ericsson Research in Aachen, Status of the 3GPP PSS (Packet-Switched Streaming) Standard, June 2004.

21. 23.3.2005T-110.45621 / N Questions, comments?