Choosing an Audio Format and Bit Rate

For practical purposes, files copied from audio CDs to your hard disk must be compressed; if you rip tracks to your hard disk using the uncompressed WAV format, a typical 60-minute CD will consume more than half a gigabyte of disk space. Compressing the files means you can store more music on your hard disk, and it makes the process of backing up music files easier and more efficient.

When it comes to compression, your first choice is simple: lossy or lossless? Most popular algorithms used to compress audio (and video) files are lossy, which means that they achieve compression by eliminating data. In the case of audio files, the data that's tossed out during the compression process consists mostly of frequencies that humans don't ordinarily hear. However, the more you compress a file, the more likely you are to degrade its audio quality to the point where you'll notice it. Windows Media Player allows you to rip tracks using the Windows Media Audio Lossless format, which stores music files more efficiently than uncompressed WAV files, without sacrificing any information . In theory, at least, a track ripped in this format should be indistinguishable from the original.

Deciding on the type and amount of compression involves making a tradeoff between disk space and audio quality. The level of compression is determined by the bit rate you select for your copied files . Higher bit rates preserve more of the original sound quality of your audio tracks but result in larger files on your hard disk or portable player. Lower bit rates allow you to pack more music into limited space, at a cost in fidelity.

INSIDE OUT

Use different bit rates for different devices

Even a truly massive music collection can fit comfortably in a fraction of the free space on today's terabyte-and-up hard drives. Saving disk space is more of a concern on portable devices with limited storage. For those occasions, why not get the best of both worlds? Save the original copy on your local hard drive or server, at the highest bit rate you're comfortable with. When syncing music with your portable device, use the sync software settings to transcode each track to a lower bit rate for more efficiency in storage. We explain how to accomplish this task in Windows Media Player in "Synchronizing Digital Media with Portable Devices" on page 450.

To set your preferences, click the Rip Settings button on the Player taskbar. Click Format, and choose one of the six available formats, as shown here. If you choose a format that allows lossy compression, click the Audio Quality option to select from choices available for that format

Rip settings **

Format Audio Quality

Rip CD automatically Eject CD after ripping

More options... Help with ripping...

Windows Media Audio Windows Media Audio Pro

V Windows Media Audio (Variable Bit Rate) Windows Media Audio Lossless MP3

WAV (Lossless)

The following options are available, listed in order of compatibility with other hardware and software:

• MP3 is the longtime standard for digital music files and has nearly universal support. If you want the widest freedom to share, play, and reuse files, this is your safest choice . The MP3 format supports variable bit rate encoding, but Microsoft's MP3 codec allows you to rip tracks at fixed bit rates only, in four steps ranging from the default setting of 128 Kbps up to 320 Kbps. (If you want to rip MP3 tracks at variable bit rates, you'll need to use a different program .) Most commercial music services offer files in MP3 format at 192 Kbps or higher.

• Windows Media Audio, which uses fixed bit rates, is the default choice. You can keep the default bit rate of 128 Kbps or choose one of five other settings ranging from 48 Kbps to 192 Kbps. In previous versions of Windows Media Player, it was possible to increase this bit rate by tweaking a registry setting. That trick no longer works in Windows Media Player 12 . If you want higher-quality encoding in WMA format, choose the Variable Bit Rate option .

• Windows Media Audio (Variable Bit Rate) allows the encoder to vary the compression applied to portions of a file, depending on the amount of information in it. Using variable bit rate (VBR) can result in files of much higher quality compared to files of similar size created using fixed bit rates. Options on the Bit Rate menu are expressed in ranges, starting with 40 to 75 Kbps and topping out at 240 to 355 Kbps . The VBR format might cause problems with some portable players and home audio devices, especially older ones; be sure any device you plan to use regularly supports it before you choose this option

• Choose Windows Media Audio Lossless if you plan to use Windows Media Player to burn custom CDs that are essentially equal in quality to the music source . This is also your best choice if you want to play tracks on a high-end audio system (including a home theater system connected to Windows Media Center) without compromising quality. Because this format is lossless, no options are available on the Audio Quality menu.

• WAV (Lossless) is the correct choice if you want nearly perfect copies of the tracks on a CD and you want those copies to be usable with any burning program. WAV files use nearly twice as much space as Windows Media Audio Lossless files and cannot be streamed as easily as compressed formats, making them unsuitable for all but temporary storage.

• Windows Media Audio Pro is primarily intended for high-fidelity output on phones and other devices with limited storage capacity. Its default bit rate is 64 Kbps, although you can choose options ranging from 32 Kbps to 192 Kbps. This format is not supported by all devices (in fact, we've never seen it used out here in the real world), so check compatibility carefully before choosing it.

Most of the options available on the Rip menu are also available in a slightly different arrangement on the Rip Music tab of the Options dialog box. Instead of choosing the bit rate from a menu, you use the Audio Quality slider, shown in Figure 12-8, to select a bit rate. Moving the slider to the left produces smaller files with lower quality; moving it to the right produces larger files with better audio quality.

3"

Figure 12-8 The Rip Settings section of this dialog box duplicates choices available from the Rip menu on the Player taskbar.

INSIDE OUT

Make a perfect copy of a CD track

If you right-click the icon for an audio CD in Windows Explorer and choose Explore from the shortcut menu, you'll see that each track is listed as a small file with the file type CD Audio Track, the .cda extension, and a date and time stamp of December 31, 1994, at 5:00 P.M. Most of that information is completely wrong and represents a confused attempt by Windows Explorer to make sense of a format it wasn't designed to read

CD Audio is not a file format; instead, these pointers serve as shortcuts to the actual files, which are stored in a format that is essentially identical to a WAV file. You can't copy a CD track directly to your hard drive from Windows Explorer, and the default ripping options compress the resulting file so that it loses some quality. Using Windows Media Player 12, you can rip a track using the WAV (Lossless) format or specify the Windows Media Audio Lossless format, which produces a file that is smaller than a WAV file but still quite large . Either format will work if your goal is to create a nearly identical copy of a CD using burning software. The WAV format is certain to work with all third-party CD-burning programs, unlike Windows Media Audio Lossless.

Notice we said "a nearly identical copy" The process of ripping a track from a CD is not perfect, especially if the media is scratched. Tiny errors caused by the mechanical operation of the drive components—a single bit here and a couple of bits there—will inevitably creep in when you rip a file, even if you use a lossless format. Similar errors can result when you use the "copy CD" option available in most commercial CD-burning software . These errors are mostly imperceptible to the human ear, but if you repeat the rip/mix/burn cycle several times the errors can add up and create a click, pop, or other noticeable glitch during playback . Perfectionists who want to make a perfect copy of a single music track or an entire CD need to take special precautions to prevent these errors from occurring . For these tasks, we recommend Exact Audio Copy, written by Andre Wiethoff and available for download from exactaudiocopy.de; this highly regarded program can reliably extract every bit of digital information from the disc, without allowing any data to be lost.

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