Last month, I discussed some of the technical aspects of one of the most important current innovations on the World Wide Web, the real-time, streamed playback of audio. Because "breaking the silence" in the online communications process can significantly enhance its impact and because the audio streaming technology is quickly being embraced by Web sites, this month's column will look at the players in both senses of the word: the players that reconstruct the sound files and allow the users to pause, resume, rewind, and fast-forward them and the players who serve up sound files on their sites. The former come from a group of five companies; the latter are a growing group of organizations and Web sites and will receive only a snapshot review here to illustrate the most typical types of audio files and services.
As a reminder, even a low-quality mono audio file, recorded at 11-KHz sampling frequency (rate) with 8-bit sampling depth (resolution) requires almost 11 kilo-bytes for each second of audio recording. This is more than six times the transfer rate of a 14.4 Kbit/second modem. A CD-audio-quality stereo file in raw format requires over 170 kilobytes for each second. It would take 50 seconds to transfer it on a 28.8 Kbit/second modem connection. In order to achieve real-time playback, the analog sound files must first be digitized, then massively compressed to provide smooth and continuous transfer over the thin pipeline of the phone cables.
In this process there is inevitable loss of quality, but these sound files are not meant to replace the high-fidelity broadcast sources and the consumer electronics devices. They are to enhance the communications experience and to provide services that are not available through traditional channels.
Sites and Sounds on the Web
The most popular sound files by far are the music samples from albums of individual artists, bands, composers, and conductors. These are provided by music stores, major and independent labels, artists' fan groups, and various music associations whose databases I review in detail in the upcoming June issue of DATABASE magazine ("Music to Your Ears and Eyes - Multimedia Music Databases"). Hundreds of thousands of such sound clips are available.
Obviously, the printed catalogs don't offer this essential feature, and the samplings in Tower Records, Virgin Megastores, and other music stores are much more limited. I had the unprecedented experience recently of being able to check out many Grammy Award winners' and nominees' songs right after the late-night broadcast of the awards ceremony. True, some of the nominated performances were available on CD, but I could sample far more songs from their albums through the multimedia music databases. Visiting these free music sites will become a favorite pastime of many Web surfers.
The second-largest group of sound files are the broadcast programs. Many radio stations (local and national ones alike) have jumped on the bandwagon since late last year. They offer broadcast programs that you would not be able to receive otherwise - not even with a shortwave radio or not at a time of your liking, and certainly not retrospectively from a searchable archive. Live broadcasts are also becoming increasingly popular, but because of their technical requirements, they are not yet as common as canned programs. Within this category, political news, business and financial news, weather forecasts, celebrity interviews, and sportscasts are the most popular. But talk shows and sermons are going to catch up soon, I believe. One of the most popular live broadcasts was the Pope's speech from New Jersey earlier this year.
The third big audio application of the year will be long-distance Internet-based telephony. One of the streamed audio technologies, Internet Wave (Inetwave for short) from VocalTec, Inc., originated from the company's Internet Phone application, which is a real money saver. …