7 Facts Audiophiles Need to Know About Digital Music

Remember back in the 1980s when you purchased your first CD?

Whether it was Billy Idol or The Psychedelic Furs, imagine if you had gone home and placed the Sony-manufactured CD in your Panasonic CD player, only to find out that it didn’t work.

Or, what if that CD from Virgin Records only had half the sound quality as a CD bought from Best Buy?

Believe it or not, this is exactly the current digital music environment in which we live.

To navigate a digital world without standards, today’s audiophiles must gain some digital music knowledge to optimize their listening experience as they convert their CDs to digital music.

To understand where we’re headed with today’s digital music, it’s key to understand where we’ve been. All digital music formats are based on the principles discovered by German researchers at the prestigious Fraunhofer Institute.

In 1987, the Institute began researching high quality digital audio compression. They discovered that by understanding how humans hear music, a particular song could be stripped of excess sounds that were inaudible.

The obvious first choice was to remove frequencies too high or too low for the human ear to perceive. However, the more interesting breakthrough was to eliminate “masked” sounds—those sounds that are hidden behind louder sounds.

During a Jimi Hendrix guitar solo, for instance, drummer Mitch Mitchell may have been producing a lot of noise of his own, but Jimi’s solo masks that sound. Similarly, in a compressed digital song, the hidden pieces of Mitchell’s drumming are removed completely, leaving the illusion of a full musical performance, but reducing the amount of information in the digital file.

The effect is analogous to a Hollywood set in a 1950s spaghetti western, where the buildings on main street appear real to the audience but are facades.

Here are seven facts about digital music that are critical whether you’re planning to install a $100,000 multi-room audio solution or simply enjoying music on your iPod in your car or at the gym.

There Are Many Flavors of Digital Music: Learn Your Formats

The end result of the Fraunhofer Institute’s digital audio research was the MP3, or Motion Pictures Expert Group Audio Layer III.

This MP3 standard for audio compression first gained a foothold in college dorm rooms in the late 1990s. In 1999, 18-year-old computer geeks weren’t too concerned with sound quality, but now they’ve grown up and so has digital music.

Many more digital audio formats have since been introduced, including these more popular formats:

  • AAC (Advanced Audio Coding) Developed by Apple and the standard for Apple iTunes.
  • WMA (Windows Media Audio) Developed by Microsoft with encoding support built into Windows XP.
  • AIFF (Audio Interchange File Format) A Professional Apple file format for storing audio files. AIFF files are high quality, uncompressed, audio files that were co-developed by Apple based on Electronic Arts Interchange File Format
  • FLAC (Free Lossless Audio Codec) An “open-source” royalty-free audio format that minimizes compression (2:1 ratio) to maintain CD audio quality
  • ALAC (Apple Lossless Audio Encoder) A CODEC developed by Apple to preserve CD quality at a lossless data compression ration of 2:1.

This alphabet soup of CODECs can be broken down into two simple subsets: Lossless (ALAC, FLAC, AIFF, WMA Lossless) and Lossy (MP3, AAC, WMA).

The main advantage of Lossless CODECs is that the file size is reduced by up to 60 percent without sacrificing the CD’s audio integrity. This, however, still requires a sizable amount of computer storage—roughly 200-400 megabytes per CD.

As the cost of storage continues to fall, Lossless CODECs provide an ideal way to create a master archive of your CD collection, which can later be burned onto blank CDs or played through high-end digital music servers with little to no audio loss.

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Meanwhile, like the name implies, Lossy CODECs do not preserve the sound quality of the original CD. The advantage, however, is that CDs can be compressed to files 10 to 12 times smaller then the original.

That’s key to the iPod revolution—so that a 500 CD collection can easily be compressed and stored on a portable player with 30 gigabytes of memory. MP3 remains the most popular Lossy standard, mainly because all brands of players can decode the ubiquitous CODEC.

Microsoft and Apple developed WMA and AAC, respectively, to address perceived deficiencies with MP3, especially at high compression rates, but these CODECs only work on limited brands of hardware.

Understand Compression Rates to Balance File Size with Audio Quality

When computer geeks talk about information, they use the term “bitrate” to describe the pieces or “bits” of information that are processed per second.

In general, the more “bits” of information included in the digital audio file, the better the audio quality. In turn, the more bits included, the larger the digital file.

That’s why it’s not enough to simply know the CODEC or format of a digital audio file, especially for Lossy formats. MP3 192 kbps (192,000 bits of information per second) is a far different listening experience than MP3 32 kbps.

This chart sums up the sound quality performance of different bitrates:

Common Bitrates for MP3, AAC and WMA Digital Audio Files

8 kbps Telephone quality: Suitable for spoken word.
32 kbps AM radio quality: Fine for voice, but music sounds hollow.
96 kbps FM radio quality: Much better music quality, but meant for portable FM radios.
128 kbps Music sold on iTunes (AAC 128) and Rhapsody (WMA 128): Small file size for downloads and portability, but sound breaks down significantly when played through stereo speakers.
192 kbps Digital Audio Broadcasting Standard: The average person may have a hard time distinguishing quality from a CD. Ideal for portable devices and headphones, but base and high range will wash out when played through a high-end audio system.
320 kbps Highest bitrate for MP3, AAC and WMA. Though still considered a Lossy format, sound quality is nearly indistinguishable from the original CD, even when played back through a high-end system. Ideal for wireless digital music transmission.
500 kbps Lossless audio, such as FLAC, ALAC, AIFF and WMA Lossless: Lossless formats reproduce CD-quality sound.
1411 kbps PCM standard for manufacturing audio CDs.

Note that digital music sold online through iTunes and Rhapsody is 128 kbps, which is far inferior to CD quality.

While the average person may not notice this through $29 portable headphones, the washed out bass and limited range will be immediately evident when the song is played through any decent home stereo or car audio system.

When choosing a Lossy format, MP3 192 is a nice compromise between file size and audio quality, while MP3 320 is twice the file size, but provides near CD-quality sound.

Online music retailers, such as Amazon, eMusic and MusicGiants, offer higher quality digital files, while iTunes recently began carrying certain titles at a higher bitrate.

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There’s a huge difference between a CD ripped by a home computer and one ripped through a professional system.

The rips are done with the same CODEC and bitrate, yet the resulting audio experience is substantially different. Not everyone can afford a million-dollar commercial CD and DVD processing system, but there are some steps you can take to optimize the quality of your rip if you are processing a CD on your home computer.

The most obvious place to start is the type of hardware and software you’re using to process a CD. The type and configuration of CD-ROM drive, for instance, can go a long way to ensure that the data you’re extracting from the CD is clean and complete.

The first step is to check the drive manufacturer and serial number to confirm that the drive supports audio extraction. Drives that vibrate or increase CD RPM to maintain linear velocity can cause substantial seek errors that translate into pops, clicks and gaps.

We’ve tested hundreds of drives, and find Plextor drives to be some of the most stable and accurate.

Here are some other basic hardware and software considerations to take into account when ripping CDs at home.

While these won’t solve your quality challenges completely, they do offer a nearly 70-percent solution.

  • Make sure CD-ROM drivers are up-to-date.
  • Use a computer with a powerful CPU, as ripping and compression are computer intensive activities.
  • Do not run unnecessary programs when ripping, and keep destination hard drive de-fragmented.
  • If you are not comfortable with configuring specialized ripping and encoding software, stick with Apple iTunes or Windows Media Player.
  • If you are going to use more robust-free programs, such as Exact Audio Copy, run some tests to make sure the CODEC output is compatible with your digital player. For instance, a program, such as dBpowerAMP, tries to imitate ALAC (Apple Lossless), which results in playback problems on some popular digital players.
  • Listen to the output of a first few CDs before dedicating the next six months of weekends to process your collection. Do it right the first time.

Once you’ve determined optimum settings for ripping on your computer and have successfully ripped at least one CD, you generally should not have to change them.

Computers Are Not Designed to Rip CDs: Consider Error Correction Software

Even with the ideal CD-ROM drive, hardware and software, computers are not originally designed for audio extraction.

An audio CD player reads data in a continuous manner, with its laser following a smooth track. Computers, on the other hand, read information in blocks.

So, blocks of audio data are read from random sectors and then written to new random sectors on the computer’s hard drive.

As you can imagine, all this disjointed sector reading and writing can leave out important information, or add unwanted new data. Based on the principle of garbage in, garbage out, desktop computers, laptops, music servers and over-the-counter carousels and mini-robots repackaged for CD ripping oftentimes produce inferior digital tracks even when CDs are new and Lossless CODECs are used.

The key is to use error-correction algorithms that read overlapping blocks, compare them, discard the inconsistencies and reread if necessary to confirm that the data on the original audio CD matches the extracted data.

This is especially important when processing used CDs, since 20 years of CD abuse makes error correction essential during the ripping process.

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For audiophiles, there are freeware programs, such as CD Paranoia, that provide relatively strong error correction.

If you’re using iTunes and are like most people, you might not realize that a rudimentary error correction program was built into iTunes that can be turned on. Go to EDIT>PREFERENCES>ADVANCED>IMPORTING and select “use error correction when importing CDs.”

Note, however, that error correction is both drive and CPU intensive, which means that it could take two to three times longer to rip a CD.

This could add hundreds of hours when ripping a large collection. Still, if you’re serious about your music, the goal should be to do it right the first time.

Clean Metadata Must Be Embedded to Digital Files

By applying the first four facts, audiophiles can create a near professional CD quality digital song. Yet, there’s another technical fact that can make or break your digital music experience.

The information about a song or artist does not live on the CD itself, so it must be added from another source or manually typed into iTunes or Windows Media Player.

Many music server manufacturers and commercial processing firms have partnered with large digital audio data companies to embed all the identifying attributes of the song: artist name, album name, song title, track number, music genre and even composer and conductor in the case of classical music.

The embedded information gives digital music some unique advantages, especially when it comes to searching and organizing vast CD collections. A specific song on a specific CD can be instantaneously located and played, no matter how large the CD collection.

If only part of the album name or a key word from a song is remembered, the correct song is still only a click or two away. Finally, a group of songs, all with common identification features, such as “Blue Grass,” can be strung together to create playlists, turning just about anyone into their own personal DJ.

Just as metadata helps those of us with mild compulsive disorders keep our music organized and at our fingertips, dirty metadata can wreck havoc on a digital music library.

Computers do what they are told and do not realize that “Dave Matthews Band,” “The Dave Matthews Band,” “DMB,” and “Dave Matthews,” are, in fact, the same artist and not four different bands.

These types of errors peppered across a 1,000 CD music library undermine many of the benefits associated with digital metadata, which is why it’s so important to that your CD ripping software has access to a clean source of data.

iTunes has partnerships with Gracenote and Muze for data and album art. Other programs may use a free database on the Internet, which will make metadata clean-up after the fact a lot of work.

For Riptopia, even though we are partners with Gracenote and Muze, we still keep a team of music majors in house to manually groom data, which is especially important for classical and jazz collections.

If you are grooming your collection yourself, you can use Windows Media Player/iTunes interfaces, or apply some useful programs, such as Tag and Rename.

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DRM May Limit the Use of Digital Music You Buy Online

If you don’t have the time, knowledge or energy to rip your CD collection yourself, or you just want to buy some digital songs online, you can apply the first five facts to become a savvy online consumer.

Check for CODEC, bitrates and quality metadata providers, such as Gracenote, Muze or AMG.

Smart shoppers must be aware of Digital Rights Management (DRM). DRM is the term used to describe software strategies used by audio content providers to control how the digital content is used.

Apple’s DRM, for instance, restricts the amount of times that a song purchased through iTunes can be copied or burned onto a CD. DRM also has the unseemly side effect of limiting playback to Apple products, such as the iPod.

So, if you just installed a $100,000 multi-room custom digital audio solution into your home, that $.99 iTunes song will not play.

Match Your Digital Components With Your New Digital Music Knowledge

Like it or not, it’s imperative to read the technical specifications of a digital player to create high quality digital music that maximizes its performance.

For instance, Escient Fireballs and Sonos systems can play the Lossless CODEC FLAC, which means that they can play back CD-quality digital music. Windows-based systems, such as Niveus and Lifeware, can handle WMA Lossless.

If you are using a Sonance iPort dock or a Russound iPod dock within your home, the iPod should be loaded with ALAC to create CD-quality sound. For wireless systems, such as Control4, or complete home audio solutions, such as Netstreams, stick with MP3 320 to maximize both sound and buffer performance.

Regardless of the hardware you choose, it is always a good idea to keep a master copy of your digital library on data DVDs or an external hard drive that is kept in a cool, dry place like a family safe.

You never know when your drive will crash, you’ll lose your iPod or want to upgrade your digital hardware.

In the digital age, content is king. A $100,000 custom home installation with Crestron components and B&W speakers will mean nothing if your digital audio quality is poor.

This holds true not only for sound quality, but also for the information, or metadata, that is embedded in the digital files. If you are an audiophile who wants to rip your CDs into digital music, take into account these seven facts so you can maximize the quality of your new digital music library.

For high-end AV integrators, applying these seven facts to custom installations will allow you to complete the job with not only the proper components, but also the proper data to optimize those components.

Written by Kurt Beyer - president and a co-founder of Riptopia and a former professor of information technology. For more information on Riptopia and its CD ripping services, please visit http://www.riptopia.com.

CE Pro - The Leading Information Source for the Custom Electronics Installer

Comments

WOW!!!!!!!!!! one of the best articles i've read!!!!!!!!!!, im really an audiophile XD , digital music is ok but as an adult its been like 2 years that i discover LP vinyls i mean at a very loud volume, like at bars or venues it is kicker than digital audio and the poppin, scratching sound is missed at high volumes, very very usefull info =].

 

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