Transcript Streaming Media Protocols

Streaming Media Protocols
Jani Hautakorpi
Henry Pohan
Contents
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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
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Protocols and Languages – Overview
Session control
• RTSP
• SIP
• H.323
• SAP
• WSP
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Media descrip.
• SDP
• SMIL
• CC/PP
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Media transpor.
• RTP
• HTTP
3/N
Session Control – RTSP (1/2)
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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.
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Session Control – RTSP (2/2)
Server
Client
Has SDP
SETUP
200 OK
PLAY
200 OK
Media
TEARDOWN
200 OK
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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, …
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Session Control – SIP (2/2)
Responder
Initiator
INVITE
180 Ringing
200 OK
ACK
Media
BYE
200 OK
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Media Description – SDP (1/2)
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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, …
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Session
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
[email protected] (Bill Huxton)
c=IN IP4 193.3.44.21
t=2873397496 2873404696
Media
Media Description – SDP (2/2)
a=recvonly
m=audio 49170 RTP/AVP 0
m=video 51372 RTP/AVP 31
m=application 32416 udp wb
a=orient:portrait
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Media Transportation – RTP
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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)
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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)
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3GPP PSS – Domain Architecture (cont.)
S treaming
Client
Content
Servers
Content
Cache
UMTS
Cor e Network
GERAN
Gb
SGSN
Iups
GG SN
Gi
IP Network
Gi
UTRAN
S treaming
Client
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Internet Multimedia
Subsystem (IMS)
User and
terminal
profiles
P ortals
Proxy
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PDP Context Activation Procedure
UTRAN/GERAN
UE
SGSN
GGSN
Activate PDP Context Request
Security Functions
RAB Assignment Request
Radio Bearer
RAB Assignment Response
Create PDP Context Request
Create PDP Context Response
Activate PDP Context Accept
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Streaming Multimedia Session
Establishment in PSS
UE
GGSN
Presentation and
Content Server
Primary PDP Context Activation
[RTSP] DESCRIBE
[RTSP] 200 OK
[RTSP] SET UP
[RTSP] 200 OK
Secondary PDP Context Activation
[RTSP] PLAY
[RTSP] 200 OK
RTP and RTCP flows
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3GPP PSS Release 6 Some Extensions
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3GPP file format:
– General profile
– Progressive-download profile
– Streaming server profile
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DRM for Streaming
– Based on OMA DRM 2.0
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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.
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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…?
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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.
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References
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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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Questions, comments?
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