CE00164-3 Multimedia Streaming
Module Information • Module code CE00264-3 • Module Title MULTIMEDIA STREAMING • Level 3 (Semester 2) • Credit Value 15 • Lecture/Teaching Areas E6 • Module Tutor • Mohamed Abdel Maguid • Room C207, Tel 01785 353324 • firstname.lastname@example.org • Module Moderator • Tim Dunning • Room C206, Tel – 01785 353433 • email@example.com
Accessing documents • Resources • Mainly using blackboard but for a week or two the documents will be available at • http://www.staffs.ac.uk/personal/engineering_and_technology/tsd1/streaming.htm
Module Outline • Media authoring and showcasing for streaming • Media Encoding • Streaming servers (technology, tradeoffs, setup and management) • Planning and managing live broadcasts • Streaming non audio/Video content (text, images and animations) • SMIL (Synchronized Media Integration Language) • Management of media rights, authentication and conditional access
Assessment Outline • Create a live and on demand streaming media station with an accompanying website to house the links • Present the website • Written document
A Reminder…Standard Multimedia and The Web • Files must be downloaded first • Will not display until all downloaded • Usually launched in a separate application • Will not be linked to the information on the web page • May not be compatible • May need converting • May need plugins • Format specific to operating system
How does it work? • File encoded and compressed to a smaller file • Break it into small packets • Send them one after the other • When the packets reach their destination, they are decompressed and resembled into a form that can be played • Playing a music or video file as it is downloaded from the internet. • Copy is never stored on the user’s computer.
How does it work? (Cont) • To maintain the seamless play the packets are buffered • Process by which the media player downloads a few seconds of the media file prior to actual playback. • Allows for uninterrupted playback as when buffer plays more packets are downloaded and queued for playback • Streaming can be opened before a download is complete • Organised to be rendered ASAP • Play as data is received
Open Connection • Streaming media files maintain an open connection • Media server and media client negotiate connection • Sent over the connection until the entire file has been received • Media clients play data over the open connection • Is buffered to overcome congestion
How do you stream? Media Server Encoder Internet
How Does Streaming Work? 2 Web Server returns location of media file User clicks on stream link Media player is launched Media player requests media file from media server Media server sends stream to media player 5 4 1 3 1 Web Server 2 3 Media Server 4 5 Media player decompresses and plays stream 6
Playback Rates • Streams can be encoded and downloaded at different bit rates. • Measured in kbps (kilobits per second). • 128 kbps is considered to be CD quality when using special codecs. • 1-2Mbps is considered to be DVD / Broadcast quality. • User’s bandwidth determines that maximum bit rate that can be played. • Can select the usual connection speed or give various options
Encoding • The process of digitizing and compressing a piece of traditional media into a format capable of being broadcast over the internet and played by a computer • Raw data is typically uncompressed • Big files - Contains all data essential to proper play • Raw data is then encoded (compressed) to stream • Encoders use audio and video codecs to compress data • Compression is different for audio and video
Codecs • Stands for Compression and Decompression • Compresses multimedia content prior to transmission, and decompresses upon playback. • This uses less bandwidth and increases playback speed. • Users must have the proper media player to stream each format.
Sound/Music Codecs • MPEG-1 layer 3 (MP3) • 8 to 256kbs • Qdesign (Quicktime) • Basic – 8 to 48kbs • Pro – 4 to 128kbs • MPEG4 (v1,v2,v3,v7) • 2kbs to 2mbs
Video Codecs • Real Video G2 • Low motion, low bit rate • MPEG4 • High quality images, low and high bit rates • Moving towards MPEG4 based standards • Apple Video • Low quality but fast
MPEG • MPEG (Moving Picture Experts Group), develops standards for digital video and digital audio compression. • MPEG-1 was designed for coding progressive video at a transmission rate of about 1.5 million bits per second. It was designed specifically for Video-CD and CD-i media. • MPEG-1 audio layer-3 (MP3) has also evolved from early MPEG work.
MPEG (Cont) • MPEG-2 was designed for coding interlaced images at transmission rates above 4 million bits per second. • MPEG-2 is used for digital TV broadcast and DVD. An MPEG-2 player can handle MPEG-1 data as well. • A proposed MPEG-3 standard, intended for High Definition TV (HDTV), was merged with the MPEG-2 standard
MPEG4 and beyond…. • The standard for multimedia for the web and mobility. • MPEG-4 is able to throw away a lot more information and to save files 8 to 12 times smaller than those of MPEG-2.
MPEG-4 • Real power of MPEG-4 is the interactivity that can built into the video file or stream. • Multimedia producers and software and game developers can isolate parts of the video for particular special effects. • Pocket PC devices, and Windows CE already play back MPEG-4 and related codecs. • PacketVideo has a whole Web site full of short videos you can download wirelessly to your Pocket PC.
Encoding Streaming Video • Choice of formats • Real Video (Helix 10) • QuickTime • Windows Media (Version 10) • Flash Video Streaming (New up and coming)
Choice of delivery speeds • What connection are you streaming to? • Dial up modem (56Kbps) • ISDN/Dual ISDN (64/128Kbps) • Cable 128 up to 20 Mb per sec • ADSL (copper twisted pair up to 2Mbs at least) • T-1 (1.5Mb’s) T-3 45Mbps’s • E-1 (more commonly called 2Mbps pipe)
Considerations for streaming • Movie size – size affects bandwidth • Frame rates – broadcast TV is 25fps most webcasts are lower • Is it audio, video or both • Encoding the media – which format • Making a website which is suitable to play a streaming file. • Serving the media
What computer hardware do you need? • A standard web server with the correct software installed OR • A specialised media server
Both have streaming capabilities but why is one better than the other? • Live Streaming requires a dedicated media server • A web server is fine for low usage streaming files but if volume of people wishing to stream from your site is above 10 at a time you need a media server. • Media Servers give you much more control for your streams and offers many more services for your clients. • Media Servers enable 2 way communication the client can say rewind your media file (only for unicast).
Media Servers • Servers needed to serve streams. • In order to stream, a web site must install media servers into it’s network. • Capacity is typically measured by the maximum number of concurrent streams that the server can serve.
Multiple Stream • From a normal web server • Content has been encoded for one bit rate only • Not really streaming, just being downloaded • TCP will resend lost packets and could cause playback pauses • Dedicated media server • Content can be encoded at multiple bit rates and the server will choose the right one • Server uses proprietary protocol to control content – can choose best transport • Server is tuned to provide optimum performance under heavy use – big beefy machine, multiple CPU’s, high memory and disk drive space.
Media Servers • Helix Server • Real Networks • Microsoft Media Server • Quicktime Streaming Server / Darwin Streaming server • Hyperlinks use a linking file • Signals the browser to launch the streaming application • URL is passed indicating the server protocol, media server, and media file • RAM / RA – Realnetworks, ASX / WMX for Microsoft
Transmission Models • Unicast • Streaming between sender and a single recipient • Multicast • Streaming between sender and multiple specific recipients • Broadcast • Streaming between a sender and any receiver • Live and prescheduled content • Some radio and television stations over WWW
Server Delivery Protocols • TCP/IP = Transmission control protocol/internet protocol. • Dedicated media servers use proprietary delivery protocols • Server attempts to provide content over UDP (User Datagram Protocol) • If unreliable or firewall then TCP is used • Allows server to control content • Content is streamed directly to the viewer and not saved or cached
Good Use Of Streaming • Streaming radio • Promotional videos • Short News Articles • Longer video broken up into chapters • Education and entertainment
Problems With Streaming • Poor quality • Screen size is small • Not ‘compelling content’ • The internet may not be fast enough • Not TV Quality
Problems With Streaming (Cont) • Compression • Discard raw data until delivery requirements are met • Audio is poor quality • Video becomes jumpy and poor quality • Low speed series of still images • Display size for video is often reduced • User Datagram Protocol (UDP) • Bad packets are removed • Audio will drop and pop • Video will drop or loose frames • Blank frames may be displayed
Problems With Streaming (Cont) • Streaming Connection • Can loose its connection • If connection is lost playback will end and must be restarted • If network is congested network will pause or delay • Popular sites can become unavailable if the network and servers cannot cope the with demand
Streaming Formats • Real • RA, RAM, RM • Microsoft • ASF, WMA, WMV • Apple • MOV, QT
RealNetworks • Real Audio / Real Video • The first and still most popular of the streaming solutions • Provides a complete creation, server and player solution • Helix announced in July 2002 • Streams all formats
Real One…. • www.real.com
Helix • The Helix Platform • the first open, comprehensive platform of digital media products and applications for any format, operating system or device. • The Helix Community • enables companies, institutions and individual developers to access and license the Helix platform source code in order to build Helix-powered encoder, server and client products and other media applications for both commercial and non-commercial use. • Helix Universal Server • is a breakthrough product from RealNetworks that for the first time streams all major media types.
Real Networks Solutions • Helix Producer • Content Creator • Real Slideshow • Assembles still photos and graphics with music and sounds
Helix Producer • RealNetworks Streaming Media creation tool • Encodes existing and live content • Wizard plus point-and-click design tools • Next generation digital media production tool for broadcast streaming and download. • It provides robust, reliable, and fault-tolerant encoding to convert audio and video into RealMedia format. • Using RealMedia Events, Helix Producer can also be used to create synchronized multimedia presentations for playback within the RealOne Player.
Helix Producer • Live and/or simulated live video and/or audio webcasts • On-demand audio and/or video • Synchronized multimedia using a combination of datatypes • Produces high quality broadband content
Helix Server • No longer it is necessary to maintain three different delivery infrastructures to reach the largest audience. • You can deliver all three major media formats over one delivery infrastructure. When you have a Helix Server, you have the capability to deliver media to any individual with a media player. • The RealNetworks system architecture based on the Helix platform has achieved unmatched performance. • Supports SMIL
Helix Server • Combine several different streams into a single file • The appropriate bit rate stream is automatically selected
Real Video 9 • 30% improvement over RealVideo 8 • Same quality at half the bit rate of MPEG-4 • Same quality at quarter the bit rate of MPEG-2 • ½ screen video at dial up rates • VHS quality at everyday broadband rates (starting at 160 Kbps) • Near DVD at 500 Kbps for download or streaming on high speed networks • http://www.realnetworks.com/products/codecs/realvideo.html
Real Networks Strategy • Leverage player penetration to drive demand for Real format, software sales, content distribution and real.com entertainment portal. • Provide end-to-end streaming solutions (encoding, hosting, distribution, security, ad insertion, playback)