Streaming - An Introduction to video streaming, live streaming, and the streamKeywords - introduction,streaming,video streaming,live streaming,stream |
- What is streaming video
- The Streaming Model
- Streaming Servers
- The Client
- The New Solution
- The Slingbox Solution
- New Model Applications
- References
What is Streaming Video?
Streaming technology is not new. Most people are familiar with it from an audio only point of view since Marconi invented radio in 1897. Most people would refer to this as broadcasting, a continuous stream of information, transmitted and received by tuning in and receive the information in real time.
Streaming across the Internet, although similar in concept, has its own issues. The Internet was not designed for real time streaming. The Internet is a shared medium and uses a best effort delivery mechanism called Internet Protocol (IP)t. There is no dedicated path between the source and the receiver. The Internet breaks content up into self contained packets and these packets are routed independently. Limited bandwidth, latency, noise, packet loss, retransmission and out of order packet delivery are all problems that can affect real time streaming over the Internet.
Traditional Internet applications are not sensitive to these problems. For example, if an email transmission is interrupted for a second, it doesn't matter. It all arrives at your computer in one piece regardless. Live or on-demand streaming however is very time critical, sensitive to the variation in delay that is normal for a shared access network like the Internet. Not only does the amount of bandwidth that you have access to matter but also the consistency or quality of this bandwidth.
It is not all about quality of bandwidth however. Content creation, serving, usability and availability are also challenges that need to be addressed. The solution was to develop sophisticated algorithms to compress the video signal into smaller and smaller files requiring less bandwidth with better stability and quality.
The Streaming Model
The components of an end to end streaming system are the client or player, the server and some sort of content creation process. As always, content is king so the greatest amount of time is spent on the creation process. Let's look at this model.
Streaming Servers
Just as a Web server (a specifically designed computer) delivers pages to Web browsers over the Internet, streaming servers deliver media clips to clients (clips are created with the production tools described here). Real time streaming requires specific servers. RealNetworks, Microsoft and Apple all provide streaming servers. These servers give you a greater level of control over your media delivery but can be more complicated to set up and administer than a standard HTTP server. Also, real time streaming uses special network protocols, such as RTSP or MMS (Microsoft Media Server).
The Client
The client is typically reception software, like Window MediaPlayer orApple Quicktime. Ideally the user should have a simple hypertext interface and have to do no more than click on a link. Any upgrade or download of a client player utility should be automated and transparent. In practice client downloads tend to be large and complicated procedures with too many options available for the average user.
Content
Until recently, any video to be streamed over a network first had to be prepared to do so. At very least, video had to be digitized, reformatted, compressed and loaded into the server before it could be broadcast, a time consuming process
Streaming availability on the global Internet should ideally mean a server ready to stream content to any clients who have an interest in receiving it. Unfortunately the demand and availability of media rich content has lead to a breakdown of the traditional client server model. Single servers streaming content to diverse groups of clients distributed across the Internet are ineffective in terms of both server load and network congestion.
Live Streaming
| Sling Media has created the Slingbox, a TV streaming device that enables users to remotely view their cable, satellite, or personal video recorder |
(PVR) with a broadband Internet connection. There is no special "content creation" and no video streaming server. A Slingbox can connects up to four live Audio/Video signals from a cable box, satellite receiver, PVR, or other Audio/Video source and on the fly, live, streams it over an IP network or the Internet anywhere nearby or around in the world.
There is a SlingBox Client. The Slingbox utilizes Sling Media's proprietary SlingPlayer to display audio and video on Microsoft Windows, Apple Macintosh running Mac OS X, and select mobile devices. Software on a user's computer or mobile device also is an onscreen virtual remote controls which provides controlling of almost all connected devices.
The SlingBox Solution
SlingStream™ automatically adjusts the video stream based on the type of input to provide the best possible viewing experience. SlingStream™ automatically adjusts the video as network bandwidth conditions change.
SlingStream also continually optimizes the video by adjusting bandwidth requirements based on the type of content you're viewing
The SLINGBOX determines what kind of device you ’re using to receive the video (PC, Mac, or mobile device) and provides the information to SlingStream™, which configures the appropriate video quality and bandwidth parameters.
Broadcast engineers at several TV stations have installed Slingboxes at remote locations to observe traffic and weather conditions. KPIX-TV in San Francisco has several connected with wireless networking. This costs only a few hundred dollars for each site, versus well over ten thousand for a setup with a remote pickup unit and auxiliary broadcast licenses.
New Streaming Applications
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References
- Motion Picture Experts Group (MPEG): <http://www.mpeg.org/>
- Real Networks: <http://www.real.com>
- Quicktime: <http://www.apple.com/quicktime>
- Sorenson: <http://www.sorenson.com/>
- Microsoft Windows Media: <http://www.microsoft.com/windows/windowsmedia>
- Sonic Foundry: <http://www.sonicfoundry.com>
- SMIL: <http://www.w3.org/TR/REC-smil/>
- Ligos: <http://www.ligos.com/>
- Akamai: <http://www.akamai.com>
- Talking Point : <http://www.talkpointcommunications.com/>
- SuperJANET4: <http://www.superjanet4.net>
