Creating a Live Broadcasting Solution Using Windows Media Technologies
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Creating a Live Broadcasting Solution using Windows Media Technologies Prepared by Calance Corp. Feb, 2006 . Creating a Live Broadcasting Solution using Windows Media Technologies Page ii Table of Contents 1. Introduction................................................................................................................................ 1 2. Streaming Media Concepts........................................................................................................ 2 2.1 Understanding Bandwidth................................................................................................................2 2.2 Live and On-demand Content..........................................................................................................3 2.3 Using Windows Media Technologies............................................................................................... 3 2.4 Planning Considerations...................................................................................................................6 3. Management Application......................................................................................................... 10 4. Hosting with Vendors............................................................................................................... 12 4.1 Akamai Streaming...........................................................................................................................12 5. References.................................................................................................................................14 Proprietary and Confidential 1.Introduction Live video broadcast of popular events (e.g. sporting events like the Super Bowl or Olympics, The Oscars or Grammy award) is no longer limited to the TV audiences anymore. There is a growing demand from people with internet connection to be able to view these broadcasts over the internet – on their personal computers. There is also a demand for archived broadcasts of such events – in case people missed the original broadcast. So, the media content providers across the globe are selling both the “live” content as well as archived content (also called Video-on-demand). A traditional TV broadcast has few limitations – first the audience has to be in front of a TV probably at their home. Broadcast over the internet eliminates that hurdle and anyone with a computer with a (high speed) internet connection can tune in. Secondly – TV still has no mechanism for protecting the copyright of the content and people can freely copy the broadcast. With DRM (Digital Rights Management) the broadcasts over the internet can be made secure and protected. These internet broadcasts also gives the audience to pick-and-choose the shows they like to watch. This new broadcasting mechanism also provides better and more targeted advertising opportunities for the content provider. For companies which broadcast live events, typically they save the content of the live event and allow people to view that off-line also. That’s why most media delivery solutions include streaming live content and also “video on demand”. Given today’s high bandwidth availability, the live content is no longer limited only to computers; it can even be made available to mobile phones or handheld computers (PDAs). But, let’s also keep in mind that building live streaming capabilities over the internet is a complex and costly project. Since the video traffic consumes much more bandwidth than a traditional website displaying text and images – proper infrastructure needs to be in place for both the content provider and the viewer. The content provider needs to setup a reliable and scalable architecture to take care of the ever-growing demand and the viewer also needs to have access to a high internet bandwidth to ensure better viewing experience. There are multiple popular formats for capturing and distributing digital video content. This white paper focuses on the Microsoft Media Technologies as the format. 1 2.Streaming Media Concepts Streaming is an emerging technology. Streaming media is generally - audio, full-motion video, and multimedia content. For our purposes, three primary characteristics combine to define streaming media, as explained below: Streaming media technology enables real-time or on-demand access to audio, video, and multimedia content via the Internet or an intranet. Streaming technology enables the near real-time transmission of events recorded in video and/or audio, as they happen—sometimes called “Live-Live,” and commonly known as Webcasting. Streaming technology also makes it possible to conveniently distribute pre-recorded/pre-edited media on-demand. In other words, media that is stored and published on the Web in streaming formats can be made available for access at any time. Streaming media is transmitted by a media server application, and is processed and played back by a client player application, as it is received. A client application, known as player, can start playing back streaming media as soon as enough data has been received—without having to wait for the entire file to have arrived. As data is transferred, it is temporarily stored in a buffer until enough data has accumulated to be properly assembled into the next sequence of the media stream. New pseudo-streaming techniques, such as progressive download, allow content in some streaming media formats to start playing before it is completely downloaded. So, while the ability to begin playback prior to completing file transfer is a characteristic of streaming, it is not, in and of itself, a differentiating factor. A streamed file is received, processed, and played simultaneously and immediately, leaving behind no residual copy of the content on the receiving device. An important advantage of streaming media (unlike either traditional or progressive download) technology is the copyright protection it provides. No copy of the content is left on the receiving device. Therefore, the recipient can neither alter nor redistribute the content in an unauthorized manner. This greatly reduces the risk of content being misused or “pirated”. 2.1Understanding Bandwidth For streaming to work properly, the player application must play the audio and video content at a steady and continuous rate. If the stream is not continuous, the picture and sound will either stop or play back unevenly. This uneven playback occurs when the content is streamed at a bit rate that is higher than the bandwidth available on the network. The amount of time needed to download the file is directly related to the size of the file, the available bandwidth of the network, and the speed of your modem or network interface card. When preparing content for streaming over the Internet—a process called encoding—it is important to consider the bandwidth that is available to the people who will be playing the stream, and then select a bit rate that is appropriate for that bandwidth. For example, a person with a 28.8 Kbps modem can potentially receive 28,800 bits per second. But it’s much more likely that they will receive less because of network overhead. So, if you are connecting to the Internet over a modem with a connection speed of 28.8 Kbps, expect that the bandwidth available for transferring data is no better than 20 Kbps, maybe less. The following table illustrates the different kinds of network connections available today, and the maximum bandwidth typically associated with each. 2 External connection Bandwidth Dial-up 28.8 to 56 Kbps ISDN 64 to 128 Kbps DSL or cable 128 to 768 Kbps T-1 1.5 megabits per second (Mbps) T-3 45 Mbps DS-3 45 Mbps Internal connection Bandwidth Cat5 100 Mbps High-bandwidth Cat5 119 Mbps Fiber optic 100 Mbps to 13 Gbps 2.2Live and On-demand Content Two delivery options are possible when streaming: live and on-demand content. 1. Live content is often used when viewers want to see and hear an important event as it is occurring. Examples might be a sporting event, presidential election, or breaking news. 2. Streaming on-demand content is the appropriate choice for times when the message is not time-critical. This delivery option enables you to re-broadcast a live event to users who missed it the first time. They can request the stream when they want to watch it, and can control the playback to meet their needs. On-demand streaming has potentially lower bandwidth requirements because hundreds (or thousands) of users may not be required to be serviced concurrently. 2.3Using Windows Media Technologies The delivery of information content through Windows Media technologies is composed of the following processes: • Capturing • Encoding • Distributing • Delivering • Playing 3 The following diagram shows the process of converting video streams and then delivering to the user: Figure 1: Process flow of working with Streaming Media To complete a broadcast stream using Windows Media technology, one must use a Windows Media- compatible encoder, server, and player. This section describes the functional purpose of these components as well as the other processes associated with the components. 2.3.1Capturing Data The capture phase takes place when you pull audio and video from its source and onto the computer using a capture card. If the source is analog, then the capture card converts the analog data to digital form before depositing it on the computer (please note that during this conversion a slight quality loss occurs). Many capture cards include a simple capture program that allows you to save the