New Trend in Information Technology. Streaming. Students: Annanda Thavymony RATH Rajveer Singh. 2005. Overview 1. Introduction 2. Characteristic of streaming 3. Different between traditional download and streaming. 4. Type of streaming. 5. Streaming protocols.
New Trend in Information Technology Streaming Students: Annanda Thavymony RATH Rajveer Singh 2005
Overview 1. Introduction 2. Characteristic of streaming 3. Different between traditional download and streaming. 4. Type of streaming. 5. Streaming protocols. 6. Different between TCP based and UDP application. 7. Caching in streaming media. 8. Live splitting. 9. Buffer allocation. 10. Compression Scheme. 11. Major Streaming format. 12. Example of streaming applications.
Introduction - What is streaming? - Streaming and batch (data) media - Why we need streaming?
Characteristics - Bandwidth dependent - Delay sensitive - Buffer requirement - Can not wait for retransmission Three primary characteristic of streaming media - Streaming media technology enables real-time or on-demand access to audio, video and multimedia content via the Internet or Intranet. - Streaming media is transmitted by a media server application, and is processed and played back by a client player application, as it is received. - Streaming file is received, processed, and played simultaneously and immediately, leaving behind no residual copy of the content on the receiving device.
Different between traditional download and streaming 1. Traditional Download - End-user has to wait until the content is fully downloaded. - Spend a lot of time. - If there is an interruption during download data, the whole file will be corrupted.
2. Streaming - No need to wait until the file is fully downloaded - User can use file progressively - Save time for end-user. - Require the specialized media server - Need high data rate and consume significant bandwidth - Streaming data is often transmitted over UDP.
Type of streaming 1. Real time (Live) - The implication is that “real time”, means “as-it-happens” or “concurrent with the reality”. - All stream is essentially real-time. - Bandwidth sensitive. - The delay must be small (Transmission+receiption) 2. On-demand - Pre-recoded, it can access any time later. - Time is not exactly concurrent.
Protocols 1. Stream control protocol - Enable user to interactively control the media stream. - These protocol typically rely on TCP. Example: RTSP, PNA, MMS, XDMA… 2. Media packet protocols - Support the real-time media delivery and facilitate the synchronization of multiple stream - These protocol rely on UDP Example : RDT, RTP, PNA, MMSU, MMST
Protocols (cont…) 3. Encoding format - Dictate how a digitized media stream is represented in a compact form suitable for streaming. - Encoding schemes commonly used Example: WMA, MP3, MPEG, real audio G2, and real video G2 4. Storage format - Define how encoded media stored in the container file, which hold one or more stream - ASF, RMFF are the example of container file formats.
Protocols (cont…) 5. Metafile formats -Provide the primitives that can be used to identify the components (URL) - SDP, SMIL and ASX are the example of the metafile formats.
1. Page download request Client Browser Web server 2. Page contents 3. Media Metafile download request 5. Media Metafile contents 4. Media Metafile Contents 6. Stream Control Media Player Media Server 7. Stream control/data Protocols (cont…) RSTP General Architecture of Streaming media request
Protocols RTP (Real Time Transport Protocol) - User UDP - One RTP session one media flow - RTP doesn’t address reservation and doesn’t guarantee quality of service for real-time services. Application Transport
Different between TCP based and UDP 1. TCP - Connection oriented protocol. - Data guaranteed. - No guaranteed for delay of the packet. 2. UDP - Not connection oriented protocol - Delay guaranteed - Not guarantee that packet always reaches the end-user.
Caching in steaming (Cont…) Limitation of caching - Object is too large. - Access patterns are not well known. - lack of well accepted transport protocol.
Live splitting A single stream from the origin streaming server is split to serve each client that requested the stream.
Live splitting (suite) +Advantage - Reduce the traffic in the network - The delay for requesting the stream is decreased. - Saving the network bandwidth between user and original server.
Buffer allocation in streaming 1. Static Buffer allocation The static buffer allocation scheme determine the minimum buffer size in the fully download state and constantly allocate it to all you user request regardless of the system’s load state. + Advantages of the static allocation - This scheme is easy to implement - Simplifying the buffer allocation. + Disadvantages - The buffer size must be greater than or equal to the amount of the data consumed by user request during a service period - Increase the initial latency of the system.
Buffer allocation in streaming Static Buffer allocation (Cont…) N <TR/CR BS(n)= (n*CR*DL*TR)/(TR-n*CR) N : is the number of the concurrent user TR: Data transfer rate (bits/s) CR : Video data’s consumption rate (bits/s) DL : Disk Latency
Buffer allocation in streaming 2. Dynamic Buffer allocation The allocation of the buffer size depend upon the request of the current users. + Advantages of the static allocation - Save the memory space for the end-user. - Decrease the initial latency of the system. + Disadvantages - Not easy to implement - Need to find the algorithms to predict the future state (load) of the network.
Stream Merging -When a new client requests a stream already in transmission. Server sends two stream concurrently (a) A “patch stream” starts from beginning. (b) A multicast stream of existing transmission. -Client must be able to receive faster data. -Client must have enough buffer
Compression Scheme -Lossy compression -Lossless compression -Psychovisual Video Compression -Psychoacoustic Audio Compression
Problems in Streaming Bandwidth Estimate the available bandwidth Match video/audio rate to available bandwidth Delay jitter Add playout buffer delay playout Loss Error control Forward Error Correction Retransmission
Major streaming format There are three major format in the streaming and each one has its own major format that have been established by the three major players in the streaming. 1. RealNetworks (RealMedia format) 2. Microsoft (Windows Media format) 3. Apple (Quick Time format)
Example of streaming Applications Realplayer -Most popular -Uses RTSP to communicate with real player -Uses two connection -Control Information -Actual Data -At transport Layer uses both TCP and UDP -Control information uses two-way TCP -Actual data uses UDP
Example of streaming Applications Realplayer (cont…) Buffering -Real media keeps the buffer -SureStream- one Clip is encoded for multiple bandwidths -Real Server determines which bandwidth to use -First bandwidth will be allocated to audio stream than to video
Conclusion and Future work We tried to briefly explain about the streaming media, its protocols, compression techniques, buffering, live splitting etc. There is much more need to study these issues in detail. In future we can analyze the stream request patterns, workload characteristics by tracing real network data. We need to pay more attention on caching, buffering and compression techniques in order to get better service.
References: . Kunwadee Sripanidkulchai, Bruce Maggs and Hui Zhang, “An analysis of live streaming workloads on the internet”, Carnegie Mellon University. . Maureen Chesire, Alec Wolman, Geoffrey M. Voelkert and Henry M. Levy, “Measurement and Analysis of a streaming-Meta workload”, department of Computer Science and Engineering, University of Washington. . Microsoft Abobe Dynamic Media Group, “A Streaming Media Primer”. . SPsilicon Press, “Streaming Media” ,www.silicon-press.com . Sang-Ho Lee, Member,IEEE, Kyu-Young Whang, Senior Member, IEEE, Yang-Sae Moon, Member IEEE, Wook-shin Han, Member IEEE, and II-Yeol Song, Member, IEEE, “Dynamic Buffer Allocation in Video-on-demand Systems”, 1041-4347/03/$17.00C 2003 IEEE. . Bing Wang, Jim Kurose, Prashant Shenoy, Don Towsley, “Mutimedia Streaming via TCP, analytic performance study”, Department of Computer Science University of Massachusetts, Amherst, MA 01003. . Eveline Veloso, Virgilio Almeida, Wagner Meira, Computer Science Department, Federal University of Minas, Brazil. Azer Bestavros, Shudon Jin, Computer Science Department, Boston University, MA, USA, “ A hierarchical Characterization of a Live Streaming Media Workload”. . Reza Rejaie, Mark Handley, Haobo Yu, Deborah Estrin, “Proxy Caching Mechanism for Multimedia Playback Streams in the internet”, Department of Computer Science, University of Southern California . . Cisco software caching configuration “Streaming Media Overview”.
Thanks Prof. Om P. Damani