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Streaming Media Protocols. Jani Hautakorpi Henry Pohan. 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 - PowerPoint PPT Presentation
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Streaming Media Protocols
Jani HautakorpiHenry Pohan
23.3.2005 T-110.456 2 / 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
23.3.2005 T-110.456 3 / N
Protocols and Languages – Overview
Session control• RTSP• SIP• H.323• SAP• WSP
Media descrip.• SDP• SMIL• CC/PP
Media transpor.• RTP• HTTP
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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.
23.3.2005 T-110.456 5 / N
Session Control – RTSP (2/2)
Client Server
SETUP200 OK
PLAY200 OK
TEARDOWN
200 OK
Media
Has SDP
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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, …
23.3.2005 T-110.456 7 / N
Session Control – SIP (2/2)
Initiator Responder
INVITE180 Ringing
200 OKACK
BYE200 OK
Media
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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, …
23.3.2005 T-110.456 9 / N
Media Description – SDP (2/2)v=0o=bill 2890844526 2890842807 IN IP4 193.34.4.2s=Streaming media protocolsi=A presentation on the media protocolsu=http://www.barfoo.com/bill/media.pse=bill@barfoo.com (Bill Huxton)c=IN IP4 193.3.44.21t=2873397496 2873404696
a=recvonlym=audio 49170 RTP/AVP 0m=video 51372 RTP/AVP 31m=application 32416 udp wba=orient:portrait
Sess
ion
Med
ia
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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
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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 – 1st version, Q1 2001– Release 5 – Q2 2002– Release 6 – Q3 2004
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3GPP PSS – Protocols
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3GPP PSS – Protocol Stack
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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)
23.3.2005 T-110.456 15 / N
3GPP PSS – Domain Architecture (cont.)
StreamingClient
ContentServers
User andterminalprofiles
Portals
IP Network
Content Cache
UMTS Core Network
UTRAN
GERAN
SGSN GGSNGi
Gb
Iups
StreamingClient
Internet Multimedia Subsystem (IMS)
Proxy
Gi
23.3.2005 T-110.456 16 / 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
23.3.2005 T-110.456 17 / N
Streaming Multimedia Session Establishment in PSS
UEPresentation 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
23.3.2005 T-110.456 18 / 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…?
23.3.2005 T-110.456 19 / 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.
23.3.2005 T-110.456 20 / 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.
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