MP3 Complete by Guy Hart-Davis and Rhonda Holmes
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SYBEX® Sample Chapter MP3 Complete by Guy Hart-Davis and Rhonda Holmes ISBN #0-7821-2899-8 MP3 Basics Copyright ©2000 SYBEX Inc., 1151 Marina Village Parkway, Alameda, CA 94501. World rights reserved. No part of this pub- lication may be stored in a retrieval system, transmitted, or reproduced in any way, including but not limited to photocopy, photograph, magnetic or other record, without the prior agreement and written permission of the publisher. 2899c01.qxd 10/5/00 1:02 PM Page 1 PART i MP3 Basics LEARN TO: 8 Understand why digital audio is important 8 Understand the advantages and disadvantages of MP3 8 Choose the right hardware for enjoying quality digital audio 8 Know what’s legal with digital audio, and what’s not 2899c01.qxd 10/3/00 7:50 AM Page 3 Chapter 1 MP3 and Digital Audio FEATURING 8 What is digital audio? 8 Why digital audio is an exciting technology 8 The short version of how MP3 works 8 Advantages and disadvantages of MP3 8 Competing digital-audio formats 2899c01.qxd 10/3/00 7:50 AM Page 4 4 Chapter One n this chapter, we’ll discuss why digital audio is such a hot Itopic and how it affects you. We’ll start by talking about what digital audio is, what you can do with it, and why you should be interested in it if you’re not already. Then we’ll switch the focus to MP3 for a bit. We’ll give you the short version of how MP3 works, its advantages and disadvantages, and why it’s currently dominating the digital-audio scene. After that, toward the end of the chapter, we’ll give you a quick heads-up on the other digital-audio formats, what’s good and what’s bad about them, and why we’ll spend most of the book showing you how to make the most of MP3 before returning to the other formats to discuss them in more depth. Digital Audio, Take 1: Studios and CDs Digital audio is audio that is stored in a digitized format rather than in an analog format. An analog signal is a continuously vari- able waveform, while a digital signal is a numeric representation of that waveform. To create a digital version of an analog sound, you examine the analog sound, measure the waveform at many regular intervals, and then store these measurements as numbers. (We’ll talk about this in more detail later in this chapter when we discuss how MP3 works.) As with analog recordings, digital audio can be any sound at all that can be recorded—whale songs, the gentle strains of Marilyn Manson, or the noise of a ten-ton truck with a cargo of live pigs dis- agreeing with a mountain bend. But instead of being stored on an analog medium such as audio tape or vinyl, digital audio can be stored and manipulated on computers. At this point, you’re probably wondering what we’re making such a big deal about. Most recording studios have been using digi- tal audio and computers for many years now, because doing so lets 2899c01.qxd 10/3/00 7:50 AM Page 5 MP3 and Digital Audio 5 them record and manipulate the sound more easily, more accu- rately, and more cheaply than using analog recording equipment. For example, with digital recording, you can much more easily sep- arate the tracks of a recording; you can clean up stray noise, edit out particular sounds, change certain frequencies of sounds, or Part i synchronize tracks perfectly. So recording studios have been using computers for recording, processing, and mixing for a long time. But once the music is fin- ished, it is typically copied to physical media for distribution to the target audience rather than being distributed electronically as a digital file. The physical media might be digital (CDs) rather than analog (records or cassettes), but CDs were designed as an audio- distribution format rather than as a computer-friendly format. There were several good reasons why CDs were designed as an audio-distribution format, and not as a media that was particularly computer oriented: 8 First, when CDs were first released, the personal-computer revolution was just starting to happen. Computers had no sound capabilities to speak of, beyond issuing peremptory bleeps in complicated sequences intended to indicate dif- ferent degrees of unhappiness. For example, three short bleeps and one long bleep on booting might indicate that the computer thought its graphics card had taken a hike. In addi- tion, the storage capacity of computers in those days was (by today’s standards) laughably small—a powerful computer would have enough storage for about 30 seconds of CD- quality audio if you cleared everything else off the hard disk. The arrival of the Amiga computer solved the first problem— the Amiga had full multimedia capabilities—but the second problem, lack of storage space, remained until the late 1990s. 8 Second, the recording industry needed a more compact for- mat for distributing audio—and a format for which it could charge more money than for records or cassettes. 2899c01.qxd 10/3/00 7:50 AM Page 6 6 Chapter One 8 Third, the recording industry was concerned about music piracy. (And today, its fears have mostly come true.) As you’ll remember if you were around at that time, it took more than a decade for CDs to rout vinyl records and cassette tapes. The first reason was the perennial chicken-and-egg problem that any new physical medium suffers when challenging an existing medium. At first, there wasn’t enough music available on CDs to convince consumers to buy CD players, and there weren’t enough people using CD players to provoke the record companies into a wholesale commitment to CDs. (At this writing, DVD is gradually breaking through a similar problem in its encroachment on videotapes.) Second, the higher prices on CDs acted as a strong disincentive for consumers to buy them. (DVD is having the same problem now.) And third, some early CDs and early CD players managed to sound worse than the analog recordings to which they were techni- cally superior: The sound was so crisp that it sounded unpleasant, particularly to those who’d grown up loving the “warm” sound of records. At this writing (July 2000), CDs dominate the music scene. According to the International Federation of Phonographic Indus- tries (IFPI to its friends), 3.8 billion units of recorded music were sold worldwide in 1999. Of those 3.8 billion units, 2.4 billion (a shade over 62 percent) were CDs, and 1.4 billion were cassette tapes and singles. In 1999, the percentage of CDs was up by 3 per- cent over 1998, which also saw total global sales of 3.8 billion units; sales of music cassettes fell by 7 percent and sales of singles fell by 4 percent from 1998 to 1999. Statistically, MiniDiscs are almost irrelevant in this picture, with a mere million units sold worldwide for the year—and half of those were sold in the U.K. (MiniDiscs are popular in the U.K. primarily because CDs are even more absurdly overpriced there than they are in most of the rest of the Western world.) 2899c01.qxd 10/3/00 7:50 AM Page 7 MP3 and Digital Audio 7 CDs contain uncompressed digital audio recorded at 44.1kHz, “CD quality,” which takes up about 10.5MB per minute (see the fol- lowing Note for the details). So the files are huge; a three-minute track takes up around 30MB, and a CD can hold up to 650MB of data or up to about 74 minutes’ worth of audio. Just storing these Part i files on a hard drive would take up a significant chunk of space— you can put about 30 full CDs’ worth of music on a chunky 20GB hard drive, but 30 CDs is laughably few to your average music fan. NOTE Tech moment: Here are the details on CD-quality audio. 44,100 samples per second times 2 tracks (stereo) times 2 bytes per sample gives 10,584,000 bytes per minute. A real megabyte is 1,048,576 bytes. (You doubtless knew that, but we mention it here because most hard-disk manufacturers call one million bytes a megabyte, which is why the typical hard disk appears to have only about 95 percent of its nominal capacity.) So a CD uses 10.09MB per minute. On a CD, each second of audio takes 75 sec- tors of 2352 bytes each. (When the CD is used for data, only 2,048 bytes of the sector are used for data—the rest is for error cor- rection and housekeeping.) So a 650MB data CD-R can hold 74 minutes of CD audio. Transferring files of 30 to 50MB from one computer to another is a pain in the seat. Floppies are pathetically inadequate; you can fit a couple of tracks on a 100MB Zip disk or a couple of dozen on a 1GB Jaz drive, and they’ll take ages to transfer over any but the sturdiest and most expensive Internet connection. Only if you’re connected to a local area network (LAN) can you afford to heave around files of this size with anything approaching frequency, and even then, your coworkers may threaten to stone you with Twinkies for monopoliz- ing the available bandwidth. So by size alone, digital audio on CDs enjoys a sort of de facto copy protection—the tracks are too big for you to copy and distribute 2899c01.qxd 10/3/00 7:50 AM Page 8 8 Chapter One easily.