The Technology of Video and Audio Streaming

David Austerberry

• Publisher: Routledge
• Year: 2013
• ISBN:
  9781136028731
• Edition: 2
• Topic: Languages & Linguistics
• Subtopic: Communication Studies
• Index: Languages & Linguistics

* Learn the end-to-end process, starting with capture from a video or audio source through to the consumer's media player
* A quick-start quide to streaming media technologies
* How to monetize content and protect revenue with digital rights managementFor broadcasters, web developers, project managers implementing streaming media systems, David Austerberry shows how to deploy the technology on your site, from video and audio capture through to the consumer's media player. The book first deals with Internet basics and gives a thorough coverage of telecommunications networks and the last mile to the home. Video and audio formats are covered, as well as compression standards including Windows Media and MPEG-4. The book then guides you through the streaming process, showing in-depth how to encode audio and video. The deployment of media servers, live webcasting and how the stream is displayed by the consumer's media player are also covered.A final section on associated technologies illustrates how you can protect your revenue sources with digital rights management, looks at content delivery networks and provides examples of successful streaming applications.The supporting website, www.davidausterberry.com/streaming.html, offers updated links to sources of information, manufacturers and suppliers.David Austerberry is co-owner of the new media communications consultancy, Informed Sauce. He has worked with streaming media since the late nineties. Before that, he has been product manager for a number of broadcast equipment manufacturers, and formerly had many years with a leading broadcaster.

Section 1 Basics

DOI: 10.4324/9780080481319-1

1 Introduction

DOI: 10.4324/9780080481319-2

Streaming media is an exciting addition to the rich media producers’ toolbox. Just as the cinema and radio were ousted by television as the primary mass communication medium, streaming is set to transform the World Wide Web. The original text-based standards of the Web have been stretched far beyond the original functionality of the core protocols to incorporate images and animation, yet video and audio are accepted as the most natural way to communicate. Through the experience of television, we now have come to expect video to be the primary vehicle for the dissemination of knowledge and entertainment. This has driven the continuing developments that now allow video to be delivered over the Internet as a live stream.

Streaming has been heralded by many as an alternative delivery channel to conventional radio and television – video over IP. But that is a narrow view; streaming can be at its most compelling when its special strengths are exploited. As part of an interactive rich media presentation it becomes a whole new communication channel that can compete in its own right with print, radio, television, and the text-based Web.

500 years of print development

It took 500 years from the time Gutenberg introduced the printing press to reach the electronic book of today. In the short period of the last 10 years, we have moved from the textual web page to rich media. Some of the main components of the illuminated manuscript still exist in the web page. The illustrated drop-capital (called an historiated initial) and the floral borders or marginalia have been replaced by the GIF image. The illustrations, engravings, and half-tones of the print medium are now JPEG images. But the elements of the web page are not that different from the books of 1500.

We can thank Tim Berners-Lee for the development of the hypertext markup language (HTML) that has exploded into a whole new way of communicating.

Most businesses today place great reliance on a company web site to provide information about their products and services, along with a host of corporate information and possibly file downloads. Soon after its inception, the Web was exploited as a medium that could be used to sell products and services. But if the sales department wanted to give a presentation to a customer, the only ways open to them were either face-to-face or through the medium of television.

Figure 1.1 The evolution of text on a page.

100 years of the moving image

The moving image, by contrast, has been around for only 100 years. Since the development of cinematography in the 1890s by the Lumière brothers and Edison, the movie has become part of our general culture and entertainment. Fifty years later the television was introduced to the public, bringing moving images into the home. Film and television textual content has always been simple, limited to a few lines of text, a lower third, and a logo. The low vertical resolution of standard definition television does not allow the use of small character heights. Some cable television news stations are transmitting a more weblike design. The main video program is squeezed back and additional content is displayed in sidebars and banners. Interactivity with the viewer, however, is lacking. Television can support a limited interactivity: voting by responding to a short list of different choices, and on-screen navigation.

Figure 1.2 Representation of cable TV news.

The Web meets television

Rich media combines the Web, interactive multimedia, and television in an exciting new medium in its own right. The multimedia CD-ROM has been with us for some time, and is very popular for training applications with interactive navigation around a seamless combination of graphics, video, and audio. The programs were always physically distributed on CD-ROM, and now on DVD. Unfortunately the MPEG-1 files were much too large for streaming. Advances in audio and video compression now make it possible for such files to be distributed in real-time over the Web.

Macromedia’s Flash vector graphics are a stepping-stone on the evolution from hypertext to rich media. The web designers and developers used a great deal of creativity and innovative scripting to make some very dynamic, interactive web sites using Flash. With Flash MX2004 these sites now can include true streaming video and audio embedded in the animation. So by combining the production methods of the multimedia disk with the skills of the web developer, a whole new way to communicate ideas has been created.

Figure 1.3 Evolution from diverse media to a new generation of integrated media.

Convergence

The media are converging – there is a blurring of the edges between the traditional divides of mass communication. Print now has e-books, and the newspapers have their own web sites carrying background to the stories and access to the archives. The television set-top box can be used to surf the Web, send e-mail, or interact with the program and commercials. Now a web site may have embedded video and audio.

New technologies have emerged, notably MPEG-4 and the third-generation wireless standards. MPEG-4 has taken a leap forward as a platform for rich media. You can now synchronize three-dimensional and synthetic content with regular video and images in an interactive presentation. For the creative artist it is a whole new toolbox.

The new wireless devices can display pictures and video as well as text and graphics. The screens can be as large as 320 × 240 pixels, and in full color. The bandwidth may be much lower than the hundreds of kilobits that can be downloaded to a PC through a cable modem or an ADSL connection, but much is possible for the innovative content creator.

This convergence has raised many challenges. How to contain production costs? How to manage content? How to integrate different creative disciplines? Can content be repurposed for other media by cost-effective processes? The technologies themselves present issues. How do you create content for the tiny screen on a wireless device and for high-definition television?

What is streaming?

The terms streaming media and webcasting often are used synonymously. In this book I refer to webcasting as the equivalent of television broadcasting, but delivered over the Web. Live or prerecorded content is streamed to a schedule and pushed out to the viewer. The alternative is on-demand delivery, where the user pulls down the content, often interactively.

Webcasting embraces both streaming and file download. Streamed media is delivered direct from the source to the player in real-time. This is a continuous process, with no intermediate storage of the media clip. In many ways this is much like conventional television. Similarly, if the content has been stored for on-demand delivery, it is delivered at a controlled rate to the display in real-time as if it were live. Contrast this with much of the MP3 music delivery, where the file is downloaded in its entirety to the local disk drive before playback, a process called download-and-play.

True streaming could be considered a subset of webcasting. But streaming does not have to use the Web; streams can be delivered through wireless networks or over private intranets. So streaming and webcasting overlap and coexist.

Streaming media has been around for 70 years. The conventional television that we grew up with would be called streaming media if it were invented today. The original television systems delivered live pictures from the camera, via the distribution network, to the home receiver. In the 1950s, Ampex developed a means of storing the picture streams: the videotape recorder. This gave broadcasters the option of live broadcast (streaming), or playing prerecorded programs from tape. The television receiver has no storage or buffering; the picture is displayed synchronized to the emissions from the transmitter. Television normally is transmitted over a fixed bandwidth connection with a high quality of service (QoS).

Today, streaming media is taken to mean digitally encoded files delivered over the World Wide Web to PCs, or IP broadcasting. Whereas television has a oneway channel to the viewer, Internet Protocol (IP) delivery has a bidirectional connection between the media source and the viewer. This allows a more interactive connection that can enable facilities just not possible with conventional television.

The first of these new facilities is that content can be provided on demand. This often has been promised for conventional television, but has not yet proved to be financially viable. Streaming also differs from television in that the media source (the server) can adapt to cope with varying availability of bandwidth. The goal is to deliver the best picture possible under the prevailing network conditions.

A normal unicast stream over IP uses a one-to-one connection between the server and the client (the media player). Scheduled streaming also can be multicast, where a single IP stream is served to the network. The routers deliver the same stream to all the viewers that have requested the content. This allows great savings in the utilization of corporate networks for applications like live briefings or training sessions. As a single stream is viewed by all, it cannot be used for on-demand delivery.

Like subscription television, streaming media can offer conditional access to content using digital rights management. This can be used wherever the owner of the content wants to control who can view; for example, for reasons of corporate confidentiality, or for entertainment, to ensure that the viewer has paid for the content.

What is real-time?

Streaming often is referred to as real-time; this is a somewhat vague term. It implies viewing an event as it happens. Typical television systems have latency; it may be milliseconds, but with highly compressed codecs the latency can be some seconds. The primary factor that makes a stream real-time is that there is no intermediate storage of the data packets. There may be some short buffers, like frame stores in the decoder, but the signal essentially streams all the way from the camera to the player. Streamed media is not stored on the local disk in the client machine, unless a download specifically is requested (and allowed).

Just because streaming is real-time does not mean it has to be live. Prerecorded files also can be delivered in real-time. The server delivers the packets to the network at a rate that matches the correct video playback speed.

Applications

Wherever electronic communication is used, the applications for streaming are endless. Streaming can be delivered as a complete video package of linear programming, as a subscription service, or as pay-per-view (PPV). It can form part of an interactive web site or it can be a tool in its ow...