Microsoft Corporation
September 16, 1996
Microsoft® NetShow™ is standards-based networked multimedia software that delivers live and on-demand content for enhanced communications over corporate networks. NetShow is an information-sharing product; it enables organizations to use Internet technologies and the power of Windows NT to solve the all too real problems of how to efficiently and effectively share rich multimedia information.
NetShow features include live multicast audio and file transfer, as well as on-demand streamed audio, illustrated audio (audio and images synchronized to a common timeline), and video. The product also provides an extensible platform. This lets software developers augment their products with NetShow functionality, or provide compatible add-ons such as codecs and authoring tools.
Microsoft NetShow exploits two key technologies to enhance a user’s networked multimedia experience, while reducing impact on the network’s throughput:
NetShow joins NetMeeting™ in Microsoft’s family of networked multimedia products. Together they provide complete information sharing solutions, spanning the spectrum from one-to-one, fully interactive meetings to widely distributed one-way live broadcasts or stored presentations.
This document focuses on the features of Microsoft NetShow On-Demand, the technology that allows you to stream audio, illustrated audio, and video over the Internet, intranets, and through specialized applications. This document is intended to lead you through the key capabilities and features that comprise this exciting new product. We hope as a result of reading this that you will get a better understanding of the problems we are trying to solve, how our products can help address those problems, and how you can start developing and using NetShow tools to add interest and impact to your intranet applications.
Microsoft NetShow On-Demand is designed to provide streaming, synchronized presentation data, as well as high-quality audio and video data streams, to accompany data stored on corporate intranets or on the Internet. NetShow On-Demand allows the content provider to place rich multimedia content on a bandwidth-limited network, and allows the viewer to experience this content almost immediately, without suffering through prolonged download times. To understand the opportunities and potential uses that this technology creates, it is helpful to first take a brief look at the Internet/intranet phenomenon in general and at the challenges and limitations involved in implementing multimedia networked applications on the World Wide Web.
The growth of the Internet has reached phenomenal proportions and is perhaps the most important platform shift to hit the computing industry since the introduction of the IBM personal computer in 1981. The World Wide Web is a key driving force in this growth and has become one of the largest repositories of information in the world. Establishing a World Wide Web presence offers organizations the opportunity to expand communications with their customers, partners, and remote employees. Organizations of all sizes are finding that the Internet gives them invaluable exposure at a very manageable cost. In short, the general growth of the Internet is a well-known phenomenon. Recitations of geometric growth abound, but the most explosive expansion will be the use of Internet technologies to improve communications within organizations. One such area is the use of intranets—Web technologies running on internal corporate or organizational local area networks.
Audio and video are becoming fundamental parts of the intranet and Internet experience. From the beginning, the World Wide Web has offered businesses and individuals the opportunity to distribute information in a more effective and compelling fashion, but Internet sites used only text because of limitations in Internet and client technologies. With the surge in capabilities of Internet World Wide Web browsers that support multimedia capabilities, Web site developers have responded with more multimedia-laden Web pages, using text with images and graphics. Now many Web site developers are starting to use audio and video content to entice more people to visit their sites.
The same phenomenon is happening inside the firewalls of corporations—people are communicating more efficiently by using audio over their corporate intranets. Experts say that people learn better when information is communicated over a variety of media. Audio is one way companies can deliver information to enhance comprehension and improve the overall user experience.
Using multimedia content to enrich Web sites offers great advantages, and Microsoft believes that Web developers will continue to use more and more of this content in the years to come. Most of the audio and video content currently hosted on intranet and Internet sites is downloadable. This means that the multimedia content must be copied to a PC before it can be played. The process of copying a file can take a long time. For example, a 3.15-second audio clip can be 30 kilobytes in size, and can take 40 seconds download over a 28.8 kilobit per second (Kbps) connection. Video is significantly more expensive in terms of storage and download time. For example, a 1/4-screen, 41.67-second video clip consumes 2.4 megabytes of storage and takes over 18 minutes to download over a 28.8 Kbps connection.
This "download-then-play" approach has seriously limited the ability of Web content authors. For example, a company that wants to enhance its site with audio explaining a product or service must keep clips extremely short to avoid annoying customers with long download times. The same limitations apply to training applications. Long video-based training applications cannot be posted on the Web because downloads would take too long and hard disk space on trainee computers would be too limited.
On a related note, companies that want to deliver entertaining music or video clips must be concerned about intellectual property issues because once the clip is downloaded to the user's hard drive, its future use is out of their control. Also, Web-based advertising is often evaluated by the number of hits to the site per day; if a user downloads the content, there is no incentive to re-visit the site and be exposed to additional advertising.
There would be no multimedia field today without dramatic advances in data networking, compression, and computing technologies. Let’s analyze the improvements in these three fields and see how they are synergistically related to the success of networked audio and video and to streaming media, the basis for Microsoft’s illustrated audio technology.
Networking
Transmission of digitized multimedia content places heavy requirements on the underlying networks. In particular, continuous media, such as sound and motion video, require both high bit rates (that is, high transmission capacity in terms of bits per second) and limited “burstiness” and transmission delays. Improvements to the network, such as fiber optics and new switching technologies, create new possibilities in the area of networked multimedia transmission. In the next few years, we are likely to see significant improvements in network bandwidth and quality of service. Microsoft’s evaluation, supported by many industry analysts, suggests that bandwidth on the Internet will continue to grow at a steady rate, specifically in the area of mid-band communications. (Mid-band is the area in the communication spectrum where ISDN and cable modems reside.) These enhanced telecommunication tools will continue to push the envelope of performance on the Internet and will enable end users to consume more services that need high processing power, such as audio and video. In the broadband spectrum, improvements in Ethernet configurations and in high-end technologies such as ATM would make transmission of video better and more reliable.
Compression
There would be no multimedia today without the dramatic progress that has occurred over the last five years in compression algorithms and in their implementation. Compression is necessary for two reasons: to reduce the storage volumes of sounds, images, and video, and to limit the bit rate necessary to transmit them over the networks. The innovation in this technology has been incredible. JPEG, MPEG, and many other efforts have constantly improved the boundaries of compression technology, making it easier to use audio and video over networks.
Our strategy is to support multiple compression technologies and multiple codecs to suit the needs of the individual content provider and to allow optimization of the specific content being produced.
Computing
The incredible improvements in hardware-based processing power are definitely driving up the curve for multimedia usage. The latest x86, MIPS, and Alpha-based processors have enabled a new class of multimedia applications. Enhancements in multimedia peripherals, computer screens, and input devices have also made the end user experience simpler and more gratifying.
Software is also key to the success of networked multimedia. Multimedia performance is directly linked to the seamless integration of hardware, the operating system, and the browser itself. Microsoft Internet Explorer uses DirectX™ technology to ensure that hardware is optimized for multimedia. DirectX allows a program to directly access the enhanced features of the hardware, greatly enhancing the speed at which graphics and other multimedia effects are rendered. In addition, Internet Explorer is tightly integrated with the operating system it runs on. Most importantly, Internet Explorer’s component object architecture and ActiveX™ technology allow multimedia to be fundamentally integrated with the browser for the best multimedia performance on the Internet.
Streaming media
Another important innovation for facilitating networked audio and video is the ability for media to stream. Streaming is a significant improvement over the download-then-play approach to multimedia file distribution. Whereas most existing multimedia content on the Internet today is downloaded to the user's hard drive before playback, streaming allows content to be "spoon fed" to the client with little waiting before playback begins. Pieces of content arrive, are buffered briefly, play, and are discarded. The entire file is never actually stored on the user’s computer. This is significant for content providers because it allows them to deliver large content files without having to anticipate how much hard disk space is available on the client's PC. Content is maintained on the provider’s site, and the user must re-visit the site to experience the content again. Users benefit by experiencing instant play; they don't have to suffer through the frustration of waiting for content to download to determine if it meets their needs or interests. In addition, they don't end up with unwanted media clips in their cache directory taking up valuable hard disk space.
As a leader in the software industry, Microsoft wants to make sure that audio and video become part of the personal computer user’s experience. To this end, Microsoft has been working on Microsoft NetShow On-Demand, a software architecture that enables the streaming and playback of multimedia content over corporate networks.
NetShow On-Demand allows users to stream illustrated audio and video from a Windows NT Server, and deliver and administer it using the features that have made WINDOWS NT Server so popular in networking and specialized applications all over the world. NetShow On-Demand offers an integrated, comprehensive, easy, and open solution for streaming multimedia content over existing network infrastructures.
NetShow On-Demand is tightly integrated with Windows NT Server and is fully compatible with the Internet information Server, Microsoft’s hypertext transfer protocol (HTTP) server technology that is now included with Windows NT. Customers moving to the Web or applying Web technologies to internal MIS solutions view this platform as the basis for building a new class of high-speed applications to extend their current environments and to take advantage of the standard Internet communication platform.
Today, MIS managers demand that both Internet and intranet applications deliver unprecedented levels of compatibility with existing infrastructures. As the use of the Internet drives standardization of long distance (even global) communications, customers will continue to require that vendors deliver industrial-strength platforms. Moreover these servers must be extensible through open, industry standards. Administration must be simple, and remote administration must be available both on the Internet and on corporate LANs, without compromising security. On such a sophisticated network, multimedia services must be simple to integrate with current platforms and applications to provide rich, diverse content.
Microsoft NetShow On-Demand seeks to deliver against this set of requirements. It runs on Windows NT Server as a dedicated service for delivering streaming multimedia data. Because NetShow On-Demand is part of the Windows NT platform, it makes use of the standard utilities and features that Windows NT provides (Performance Monitor, Event Viewer, security, and so on) and provide support for standard network environments (IP, IPX, 14.4/28.8 POTs, ISDN, Ethernet, and so forth).
On the client side, NetShow On-Demand works with Microsoft Internet Explorer. Internet Explorer is the Web browser that puts you a step ahead on the Internet. With ActiveX, Java™, Plug-in, and broad HTML support, Internet Explorer provides the best browsing experience and most technically advanced development platform for end users, organizations, and content providers. NetShow On-Demand provides an ActiveX control that developers and content providers can use to incorporate illustrated audio in their HTML pages and client applications. The ActiveX control offers an easy-to-use programming interface that lets the developer manage multimedia streams using the control's properties, methods, and events. The control handles all video and audio rendering, simplifying programming tasks and making it easy to add support for multimedia streams to applications.
Microsoft NetShow On-Demand offers a complete and easy solution for streaming content on the Internet and intranets. NetShow On-Demand includes a set of simple and practical tools to enable server administration, server management, content authoring, content encoding, and client development.
The popularity of Windows and Windows NT continues to grow due to the graphical user interface and reduced requirements for end user support. Customers want this improved usability for Internet servers, especially in small and medium-sized business where it is unlikely that they would have a UNIX expert on staff to take advantage of the Internet phenomenon. NetShow On-Demand is fully in line with this usability goal. Installation is simple and requires little effort from an administrator. The same is true for modifying or removing the installation. NetShow On-Demand allows the server operator to easily add multimedia content, select default server options, or secure specific areas of a server. In addition, administrators can easily set and adjust bandwidth and client connection limits to manage network load.
NetShow also provides an extensible platform, enabling software developers to either provide compatible add-ons, such as codecs and authoring tools, or augment their own products with NetShow functionality.
NetShow On-Demand offers an open solution: exposed application programming interfaces (APIs) allow application developers to incorporate the technology in new applications, and the architecture is not tied to a particular transport, compression technology, codec, or data type.
As the Internet continues to flourish and more and more intranets come into play, it is clear that no single client application, content development application, or administrative tool will meet the needs of all customers. Therefore, it is critical that third parties be able to extend the basic client delivery, content creation tools, and administrative and content management services included in this product. In this way, new and exciting applications can be developed, not only by software developers, but also by independent content providers and corporate developers.
Microsoft is currently working with leading network software and hardware companies, systems integrators, codec vendors, and content tool providers to offer network components, compression technologies, authoring tools, administration utilities, applications, and services to provide end-to-end networked multimedia solutions.
These efforts are designed to allow third-party Solution Partners to bring products based on NetShow technology to market quickly by building on top of Microsoft’s NetShow On-Demand, rather than re-inventing an entire streaming media system. Initially, Solution Partners can add value to Microsoft NetShow On-Demand by offering new codec technologies. More advanced Solution Partners may wish to build content creation tools and unique clients. At the core of these products will be the Microsoft NetShow On-Demand Server and the ActiveX streaming format (ASF).
Illustrated audio is a term we use to generically describe the content type that NetShow On-Demand software architecture stores and delivers. Illustrated audio is a new way of sharing ideas and information on narrow and mid-band networks. It synchronizes graphic images, such as video frames, still pictures, or Microsoft PowerPoint® slides, with an audio track to create an interesting and effective interactive multimedia presentation, similar to an online slide show.
When working with video material, an author of illustrated audio can pick key frames to illustrate and augment the sound track, and thereby avoid the problems of random frames seen with slow-scan or reduced frame rate systems. If more bandwidth is available for video, the author can increase the number of frames per second, increase the size of the image, and increase the quality or sharpness of the individual images. This trade-off between the bandwidth available on a given network and the demands for quality and performance determines how content authors should develop their illustrated audio content.
Using NetShow On-Demand, a content provider can also enrich a site with AVI and Apple® QuickTime® content. Because AVI and QuickTime files are the most popular methods of storing multimedia content on the Internet today, NetShow On-Demand makes it easy to leverage the equity that content providers have in these popular formats. NetShow On-Demand can also store and transmit audio-only WAV files.
NetShow On-Demand enables the content provider to enrich intranet-based applications with audio, illustrated audio, and video content. Corporate, educational, retail, and government enterprises can turn networked mixed-media content into serious productivity tools for desktop and classroom training, distance learning, information delivery, customer support, corporate communications, work group collaboration, and more. This will improve the effectiveness of communications through an efficient use of visual elements, and will improve the effectiveness of business operations through a more potent information delivery system.
Microsoft NetShow On-Demand is made up of server, client, and content authoring and encoding components. The server component allows customers to host illustrated audio and video on a Windows NT Server for fast, reliable, streaming delivery over corporate intranets. The client software enables users equipped with conventional multimedia personal computers connected to voice-grade telephone lines or corporate LANs to browse, select, and play illustrated audio and video content on demand, in real time. In addition, NetShow On-Demand provides a set of tools for creating illustrated audio content and for enabling existing multimedia content (such as WAV, AVI, and QuickTime files) to stream from the server.
Microsoft NetShow On-Demand Server is tightly integrated with Windows NT Server and leverages Windows NT features to provide an easy, flexible, efficient, reliable, scalable, and secure platform for streaming audio, illustrated audio, and video content over corporate intranets. The server uses the Windows NT File System (NTFS) to store files meant for streaming via standard Win32® APIs. When the server receives a client request for data, it identifies the file requested and reads it to a buffer for transmission. The server is able to segment data in optimally sized pieces for network and client consumption, and can determine when a given file packet is timed for arrival at the client. The server schedules its workload, sending data packets to the client just in time for consumption.
Note that the server’s operations are remarkably efficient. Although data is streamed to the client in small pieces, the server reads large, contiguous pieces of the file to its buffer to conserve processor and disk resources. The server component also provides multiprocessor support; its disk and network operations are performed asynchronously to ensure that all processors are used.
Because customers have told us that performance is an important consideration for them when selecting a streaming server, we built NetShow On-Demand from the ground-up to enable fast response on multiple bit rates, ranging from audio at 14.4 to AVI at several megabytes per second (Mbps), and to maintain quality of content even in heavy load situations. The server accomplishes this by giving data operations (such as reading and sending data to current clients) priority over a client's control requests (such as new requests for streaming media or “VCR” actions—stop, pause, and start). For example, if the server is busy transmitting data and a stream request arrives from a new client, the server will complete its data operations before starting the new client request. If the server is very busy, the new request may be rejected or may time out. This ensures that currently scheduled clients do not experience degradation in service due to an influx of new control requests.
Our solution builds on the inherent portability and scalability of Windows NT Server, which runs on thousands of standard hardware platforms, including single- and multiprocessor servers using a variety of different processors. On standard Windows NT Server hardware configurations (single Pentium computers with 32MB RAM), NetShow On-Demand scales from few to hundreds of simultaneous streams: the alpha release was tested up to 200 streams at 28.8 kilobits per second (Kbps), and the current beta scaled to 1000 streams at 28.8, and more than 500 streams at 100 Kbps. NetShow On-Demand currently supports WINDOWS NT striping, and future testing will include RAID devices.
NetShow On-Demand includes extensive LAN/WAN support on any IP network. Content streams are transported using UDP, and control streams are transported via TCP. To ensure optimum usability, network topology is independent. Firewall support will be included in the released version of the product.
NetShow On-Demand optimizes streaming capability and content for our server platform (Windows NT Server), and can be easily ported to any server platform on which Windows NT runs. In addition to leveraging the portability of the Windows NT platform, we take advantage of the administrative tools provided by Windows NT and the Internet Information Server. These tools provide the administrator with a consistent and easy-to-use graphical interface to perform all administrative tasks on a NetShow On-Demand Server. The same tools (Control Panel, Performance Monitor, Event Viewer, and so forth) are used to administrate and monitor Windows NT Server.
With NetShow On-Demand Player, intranet surfers can play audio (sound only), illustrated audio (synchronized sound and still images), and full-motion video files. When the user simply activates a link to a file, the player launches automatically and begins playing the file requested. Within just a few seconds, the content starts to play—with no download required. NetShow On-Demand Player enables the same functions as a regular VCR; the user can stop, pause and start content. This enables a user to control the flow of content as appropriate for his or her needs.
Application developers can incorporate the ability to play illustrated audio and video content within a stand-alone client player or as an integrated part of a Web-based application. This enables developers to integrate multimedia content into their Web pages, creating more interesting interactive applications. NetShow On-Demand provides a simple client SDK, which contains software and documentation that developers can use to add streaming support to Visual Basic and Visual C++ applications. The SDK includes an ActiveX control, reference documentation, and sample programs. The control is an easy-to-use programming interface that lets a developer manage multimedia streams using the control's properties, methods, and events. The control handles all video and audio rendering, simplifying programming tasks and making it easy to add support for multimedia streams to new applications.
The current beta release of the product provides two versions of the player: a Windows® 95 version and a Windows NT version. Macintosh® and Windows 3.1 versions will be made available later in the product cycle.
One of our major objectives when developing NetShow On-Demand was to make content creation easy. To this end, NetShow provides simple starter tools to enable corporate content developers to prepare many popular content formats for streaming as illustrated audio. Files in WAV, AVI, QuickTime, PowerPoint, JPEG, GIF, and PNG formats can all be used to generate illustrated audio. In addition, content can incorporate calls to uniform resource locators (URLs). NetShow also provides the capability to synchronize different data types on a common timeline. By synchronizing many different types of content, a content provider can generate a more interesting and compelling end product.
The NetShow software architecture is designed to be completely codec-independent. This means that the content provider can choose the compression scheme needed for a specific application and is not tied to a proprietary compression scheme.
The current release of NetShow On-Demand works with a variety of codecs to enable the immediate authoring of content. The number of codecs supported will continue to increase as the product develops; this means that content providers can leverage improvements in codec technology to deliver better performance and quality of content.
The ActiveX streaming format (ASF) is an important part of the Microsoft streaming architecture, and is the technology that enables the efficient storage of multimedia content in preparation for network delivery.
Let’s briefly summarize the characteristics of the format architecture. ActiveX streaming format allows multiple types of data—for example, audio objects, video objects, still images, URLs—to be combined into a single synchronized multimedia stream that can be stored on a variety of servers and transmitted over a range of networks. The format does not replace existing formats, such as AVI, WAV, and QuickTime, but rather repackages them for more generalized storage and transport. ASF provides the following key benefits:
ASF is a basic technology for the NetShow On-Demand content strategy. It provides the server, media, and transport-independent architecture upon which we built the current implementation of our content tools. Future versions of NetShow On-Demand will build on this architecture and the content tool facilities currently provided to support new data types and to provide enhanced tools, greater ease of authoring, and richer illustrated audio capabilities.
With ASF Editor, a content author can create, test, and compile an ASF file to store illustrated audio content. The tool is designed to handle most of the issues of encoding and timing so that the author doesn't have to. It determines where to place objects—sounds, images, and uniform resource locators (URLs)—so that they appear at the correct time during playback.
The key features of this tool are the following:
ASF Editor displays an illustrated audio file so that the author can see when objects will appear and how they are stored. It also has the ability to convert objects from one format or one level of quality to another. On networks with low bit rates, this ability becomes very useful in determining the trade-offs between sound and image quality.
One example where ASF Editor finds its perfect use is the creation of advertising content. Many corporations are investing a great deal of money and time in advertising on the Web and in using their Web sites to drive the sales of their products. Illustrated audio provides a great help in this process; content providers can use it to illustrate the benefits of their products to their customers. ASF Editor provides a great authoring paradigm for these Web sites by enabling a very precise synchronization between many images and an audio track.
The upcoming releases of Microsoft NetShow On-Demand and Microsoft PowerPoint will include a tool to convert PowerPoint presentations to illustrated audio content by time-synchronizing PowerPoint slides and audio content into an ASF file. This tool is not included in the current beta, but it will be made available in Microsoft Office 97.
The PowerPoint conversion tool can be used effectively in the creation of content for personal or corporate communications. Authors can use the tool to prepare streaming media presentations for coworkers or distant friends and relatives, enabling the audience to have immediate and constant access to the information. This same tool is valuable for corporations that want to store presentation or training materials.
NetShow On-Demand provides a set of command-line utilities that allow a content author to quickly convert an AVI or QuickTime video or a WAV audio file to a file so that it can be stored on a NetShow On-Demand Server and streamed to clients.
As an example, the video conversion tool (VidToAsf) facilitates the creation of streaming media content from videotapes. To do this, the content author uses a video capture card to transform the videotape content to AVI (or to another supported video format). The content author uses the card to reduce the number of frames in the AVI file and thereby reduce the amount of data that needs to be sent over the network. After this step, the author uses the conversion tool to convert the AVI file into ASF file; the file is then ready to be stored on the server and streamed to clients.
Microsoft believes that in the next few years bandwidth capability will continue to improve dramatically. These improvements include broadcast capability, ISDN, ADSL, and cable modems. These improvements will create expectations and opportunities for multimedia content providers. To meet these needs, we will continue to invest in streaming technologies that enable our customers to use and deploy greatly enhanced networked multimedia content over corporate intranets. A few of the next steps in this ongoing effort include streaming of MPEG-1 and MPEG-2 data, and delivery of full-screen video to standard PCs.
Microsoft is integrating Internet connectivity and standards into the PC world with Microsoft ActiveX technologies, an open technology platform that provides exciting new Internet capabilities while extending and capitalizing upon the investments of the Windows operating system. In this spirit, Microsoft will continue to develop better client and tool software to facilitate the creation of illustrated audio and video content and their integration within Web applications.
In addition, Microsoft will continue to improve the efficiency of illustrated audio and video transmission over a variety of networks. In this regard, Microsoft is engineering multicast services to enable increased efficiency in how multimedia gets transmitted over a network. Also, the inclusion of new services that provide quality of service guarantees will enable multiple audio and video streams to share networks in a more efficient way while ensuring that the quality of the user’s experience remains constant during file playback.
It is Microsoft's belief that streaming media is a fundamental intranet and Internet service. Streaming media services will help corporations and individuals collect and disseminate information in forms other than pure text. Illustrated audio is key to this Internet strategy. Audio is powerful but does not provide any visual elements; full-motion video requires too much bandwidth. Illustrated audio joins the power of audio and the impact of visual elements, such as slides, photographs, and artistic images, to provide more powerful ways of expressing ideas and communicating information to corporations, content providers, and individuals. And it accomplishes these things on the low-bandwidth connections that the Internet currently offers. Microsoft sees illustrated audio as the best way to get ideas across corporate intranets.
NetShow On-Demand is fully integrated with Internet Explorer on the client side and with Windows NT Server and the Internet Information Server on the server side. It requires no specialized software and hardware. NetShow On-Demand is the easiest and most cost-effective way to stream illustrated audio and video across intranets and the Internet.
Microsoft’s goal in developing this product was to meet the demands of customers for simple, yet fast and reliable streaming of multimedia content over today’s networks. We also designed this platform to provide growth in the future. Microsoft is focusing heavily on customer requirements; we are soliciting feedback from key industry partners and alpha/beta testers to ensure that we have not lost focus during the development cycle. Our success will be determined by our ability to deliver an industrial strength technology that grows with customer needs and provides a platform for industry innovation.