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5.3. Selecting the right format

Each format discussed in this chapter has advantages and disadvantages depending on the requirements of your project. There is no single format appropriate for every situation. To determine which format is best for you, first identify your needs, then select the format that best suits those needs. There are huge differences in server requirements for broadcasting CD-quality music to a limited audience versus wide-scale broadcasting to a large audience with diverse bandwidth capacity. Similarly, the differences between authoring and delivering interactive content such as a game or product demo versus encoding and broadcasting a video file are completely different.

RealAudio, MP3, and Flash are familiar names, but a host of alternative formats, including Windows Media, RMF, and Liquid Audio might better suit your needs. Let's take a look at the factors that will determine the most appropriate format for you.

5.3.1. Interactive sound design capabilities

Before you look at browser compatibility, cost, audio fidelity, and server performance, you will need to determine whether you need a format that supports interactive presentations or one that supports continuous playback of audio and video files. Several formats such as Flash, Shockwave, and Beatnik are designed for rich interactive media content such as games, educational material, product demos, and promotional pieces where instantaneous feedback via sound effects are essential.

In contrast, formats such as RealMedia, MP3, Windows Media, and QuickTime are primarily designed for continuous playback of audio and video files where server-side bandwidth negotiation and management are key. When they do support interactivity, it is usually in a more limited form such as slide shows and synchronized sound with video or text.

First, determine whether you want a format for delivering interactive content or simply a format for encoding and broadcasting audio and video files, then let the following criteria guide your final decision.

5.3.3. Cost for streaming audio

To add streaming to your web site, you may need to purchase one or more of the following:

  • Encoding software to convert your raw media files into the appropriate format for web delivery

  • Dedicated server software to stream your encoded media files

  • Hardware to install your server on (this may include several systems for redundancy and scalability)

  • Bandwidth to transmit data from your server over the Internet

The cost of streaming can range from free to hundreds of thousands of dollars depending on how many of the above items you will need to purchase. For example, if you are already running an NT server and have a dedicated T1 line, you can use Windows Media for no extra cost. Some vendors provide free introductory-level streaming solutions such as Real Networks. If you have administrative access privilege to your web server, you can install the free Basic RealServer G2. Alternatively, if you are a multimedia producer and own a copy of Macromedia Director or Flash, you can export Shockwave files and stream them from your regular web server for free.

On the other end of the spectrum, if you are a major Internet portal running a hot Sun machine with thousands of simultaneous listeners, you are going to need a healthy budget for equipment and bandwidth and, if you are using RealMedia, the appropriate number of streaming licenses. Keep in mind that you may not need to spend as much on streaming licenses as you may have thought. A 60-stream license can go a long way. If your average user listens to your audio for five minutes or less, you can deliver 17,280 streams per day with a 60-stream license.

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