From the site www.informit.com I found some articles by Mike Miller that will help us all understand the different music formats that everyone has a different opinion on. For newbies, such as myself, I think it helps explain some of the jargon that we sometimes get lost translating. I hope it helps others as well. Below is part 1:

HOW DIGITAL SAMPLING WORKS:

Even if you've never downloaded any music from the Internet, chances are you've still heard of MP3 files. MP3 is a particular type of digital audio format that compresses music to fit within reasonably-sized computer files—while maintaining near-CD quality sound.

As popular as the MP3 format is, it's not the only digital audio format you'll encounter online. There are several other ways to compress music into relatively small audio files, many with far better sound than the MP3 format, that you can consider for use when you rip your own CDs to hard disk.

When you copy a digital audio file, you can either copy the file exactly (in non-compressed format) or you can use some sort of compression to reduce the otherwise-huge file sizes. If you choose a compressed format, you can opt for formats that use either lossy or lossless compression. Lossy compression loses some of the original audio information to create a smaller file, resulting in music that isn't quite as good-sounding as the original. Lossless compression doesn't affect the original sound quality, but results in larger files sizes—although not near as big as non-compressed files.

If you want to rip your music for playback on your computer or a portable music player, you'll probably use a lossy compression format, such as MP3, AAC, and WMA. If you want to archive your CD collection for playback on a home audio or home theater system, you'll probably want to use a lossless compression format, such as FLAC or WMA lossless, or copy your CDs in non-compressed format.

Read on to learn more.

How Digital Sampling Works
All digital recordings—starting in the recording studio—are made by creating digital samples of the original sound. The way it works is that special software "listens" to the music, and takes a digital snapshot of the music at a particular point in time. The length of that snapshot (measured in bits) and the number of snapshots per second (called the sampling rate) determine the quality of the reproduction. The more samples per second, the more accurate the resulting "picture" of the original music.

Compact discs sample music at a 44.1kHz rate—in other words, the music is sampled, digitally, 44,100 times per second. Each sample is 16 bits long. When you multiply the sampling rate by the sample size and the number of channels (two for stereo), you end up with a bit rate. For CDs, you multiply 44,100 X 16 X 2, and end up with 1,400,000 bits per second—or 1,400Kbps.

All these bits are converted into data that is then copied onto some sort of storage medium. In the case of CDs, the storage medium is the compact disc itself; you can also store this digital audio data on hard disk drives, or in computer memory.

The space taken up by these bits can add up quickly. If you take a typical three-minute song recorded at 44.1KHz, you end up using 32MB of disk space. While that song can easily fit on a 650MB CD, it's much too large to download over a standard Internet connection, or to store on a portable music player.

This is where audio compression comes in. By taking selected bits out of the original audio file, the file size is compressed. If the right bits are excised, you'll never miss them.




Edited 1 time(s). Last edit at 2006-03-09 17:06 by The Sicilian.

Here is part 2:

LOSSY COMPRESSED FORMATS


Lossy compression works by sampling the original file and removing those ranges of sounds that the average listener can't hear. A lossless encoder uses complex algorithms to determine what sounds a human is able to hear, based on accepted psychoacoustic models, and chops off those sounds outside this range. You can control the sound quality and the size of the resulting file by selecting different sampling rates for the data. The less sampling going on, the smaller the file size—and the lower the sound quality.

The problem with shrinking files to this degree, of course, is that by making a smaller file, you've dramatically reduced the sampling rate of the music. This results in music that sounds compressed; it won't have the high-frequency response or the dynamic range (the difference between soft and loud passages) of the original recording. To many users, the sound of the compressed file will be acceptable, much like listening to an FM radio station. To other users, however, the compression presents an unacceptable alternative to high-fidelity reproduction.

The most popular lossy compressed format today is the MP3 format, although there are lots of other formats that work in the same fashion. Here's a list of available lossy formats:

Advanced Audio Coding (AAC)—Also known as MPEG-4 AAC, this is the proprietary audio format used by Apple's iTunes and iPod. AAC offers slightly better sound quality than MP3 files along with strong digital rights management (DMA), to prevent unauthorized use. Unfortunately, most non-Apple music players won't play AAC-format songs—but if you're an iPod user, this is the format you'll be using.

ATRAC3 (OMA, OMG)—OMG stands for Open Magic Gate, which is the digital rights management wrapper Sony uses for its proprietary ATRAC3 digital audio format. (For what it's worth, ATRAC3 stands for Adaptive TRansform Acoustic Coding 3.) The ATRAC3 and newer ATRAC3plus formats offer good sound and decent compression, along with strong digital rights management. Incompatible with everything except Sony products.

Liquid Audio (LAT, LQT, LSL)—An MP3 competitor from Liquid Audio, somewhat popular in the late 1990s but not widely used today.

MP3 (MP3)—Short for MPEG-1 Level 3, the MP3 format remains the most widely-used digital audio format today, with a decent compromise between small file size and sound quality. The primary advantage of MP3 is its universality; unlike most other file formats, just about every digital music player and player program can handle MP3-format music.

mp3PRO (MP3)—This is an improved version of the original MP3 format, introduced in 2001 but not in wide use today. mp3PRO files use the same file extension as regular MP3 files.

OGG Vorbis (OGG)—An open-source encoding technology originally known as "Squish," OGG Vorbis was designed as a substitute for MP3 and WMA. It uses variable bitrate compression, which encodes different parts of a song with higher or lower compression, to produce better quality when needed.

QuickTime Audio (MOV)—Essentially the same MPEG-4 technology as the AAC format,
RealAudio Media (RA, RM, RMA)—Proprietary format used by Real Networks, designed particularly for real-time streaming audio feeds.

Windows Media Audio (WMA)—Microsoft's digital audio format is promoted as an MP3 alternative with similar audio quality at half the file size. That may be stretching it a bit, but WMA does typically offer a slightly better compromise between compression and quality than you find with MP3 files. It also provides strong digital rights management.

Here is part 3:

LOSSLESS COMPRESSED FORMATS:


If you care about audio fidelity, lossy compression just doesn't cut it. No matter high the sampling rate or how good the compression algorithm, lossy files don't sound quite as good as the originals. (Remember that word "lossy"—you lose something in the translation!)

If you want to create a high fidelity digital archive, a better solution is to use a lossless compression format. These formats work more or less like ZIP compression; redundant bits are taken out to create the compressed file, which is then uncompressed for playback. So what you hear has exact fidelity to the original, while still being stored in a smaller-sized file.

Of course, a lossless compressed file isn't as near small as a file with lossy compression. While an MP3 file might be 10% the size of the original, uncompressed file, a file with lossless compression is typically about 50% the original's size. This is why lossless compression isn't recommended for portable music players, where storage space is limited. If you're storing your CD collection on hard disk, however, it works just fine—especially with today's cheap hard disk prices. You can easily store 1,000 CDs on a 300GB hard disk, using any lossless compression format.

What formats can you choose from? The list isn't quite as long as with lossy compression, nor or the formats quite as well known. Here's a short list:

Apple Lossless Audio Codec (ALAC, M4A)—A lossless compression option available for use with Apple's iTunes and iPod.

Free Lossless Codec (FLAC)—An open-source lossless format, embraced by many consumer electronics manufacturers and usable with all major operating systems, including both Windows and Linux.

Monkey's Audio (APE)—A free lossless format, not widely used.

Windows Media Audio Lossless (WMA), Microsoft's lossless compression format, available in Windows Media Player versions 9 and 10—probably the best option for lossless compression today. (Uses the same WMA file extension as normal Windows Media Audio files.)

WavPack (WV, WVC)—An open-source lossless format, similar to FLAC, not yet widely used.

The final installment part 4:

NON COMPRESSED FORMATS:


Compressed audio is the way to go when you're ripping your own music or creating a digital media archive. But the original digital music files you find on a CD are uncompressed, as are digital sounds used by your computer's operating system. If you insist on archiving your music in its original unaltered form, you'll want to use one of the following uncompressed digital audio formats:

AU—A file format (abbreviation for "audio") that originated on the Sun and NeXT computer systems. Not widely used today.

Audio Interchange Format (AIF, AIFF)—File format for Macintosh system sounds, similar to Windows' WAV format.

Compact Disc Digital Audio (CDA)—This is format used for encoding music on all commercial compact discs. If you buy a CD from a store, the music on that CD is stored in CDA format. Unfortunately, your computer can't store files in CDA format, so you still have to convert CDA files to another format to store on your hard disk.

SND—Another file format (abbreviation for "sound") similar to the AU format and used primarily for Macintosh system sounds.

Waveform Sound Files (WAV)—This format (pronounced "wave") produces an exact copy of the original recording, with zero compression. The result is perfect fidelity but with very large file sizes—the same size as the original, in fact. It's not a good choice for portable use, because it takes up too much storage space, but it's the preferred format for uncompressed archiving.

There's one last digital audio format that you should be aware of, even though it's not used for recording music from CDs. The MIDI format, short for Musical Instrument Digital Interface, is used by professional musicians to reproduce instrumental music in very compact files. MIDI doesn't record an actual performance; instead, it creates a kind of roadmap for frequencies and rhythms that can be fed to synthesizers and other musical instruments for playback. It's often used to create background music on Web pages (with .MID format files), and to record musical "sequences" for various home- and studio-based recordings.

Thanks. But I'm missing the SHN ("shorten") format which sometimes appears on torrents.

Nice information - thanks for posting!