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CD Burning Terminology

Advanced Audio Coding is an audio compression technology that is part of the MPEG-2 and MPEG-4 standards. AAC, especially MPEG-4 AAC, provides greater compression and superior sound quality than MP3 (MP3 is also an MPEG specification). MPEG-4 AAC (MPEG-4 audio) has become popular because of Apple's iPod. Apple's iTunes music store sells titles in the AAC format that are copy protected and use the M4P file extension. With the iTunes jukebox software, CDs can be ripped to the AAC format as well.

A representation of an object that resembles the original. Telephones turn voice vibrations into electrical vibrations of the same shape. Analog implies a continuous signal in contrast with digital, which breaks everything into numbers. Once recorded, analog equipment, no matter how modern, cannot copy signals perfectly. Third and fourth generations of analog audio and video recordings show marked deterioration. By recording in digital from the beginning, or by converting from analog to digital at an early stage, audio and video data can be preserved indefinitely and copied over and over without deterioration. Analog means copies of copies are not the same; digital means they are. Analog means an infinite signal resolution (within boundaries); digital means a predefined, fixed resolution. However, in the resolution department, digital is catching up and perhaps exceeding analog. Digital cameras with multi-megapixel resolution and high-definition digital audio (SACD, DVD-Audio) are getting closer to analog all the time.

Bit Rate
While 128 Kbps (kilobits per second) is considered the norm for good quality MP3 files, MP3s can be ripped to bit rates from 8Kbps to 320 Kbps. The higher the bit rate, the better the sound and the larger the file. The sliding lever in the following dialog box, taken from Windows Media Player 10, is used to select four bit rates for encoding MP3s: 128, 192, 256 and 320 Kbps.

To write a write-once optical medium such as a CD-R or DVD-R disc. A CD-R is "burned," because once recorded, it cannot be erased and rewritten. The term is also erroneously used with rewritable media such as CD-RWs. Rewritable media are not "burned;" they are "written."

Compact Disk - Digital Audio

(1) (enCOder/DECoder) Hardware that performs analog-to-digital conversion (ADC) and digital-to-analog (DAC) conversion. ADC and DAC codecs are built into chips. When analog signals are entered into a computer, cellphone or other device via a microphone or video source such as VHS tape or analog TV, an ADC creates the raw digital audio samples and video frames. The results are then further compressed to save bandwidth.
(2) (COmpressor/DECompressor) Software or hardware that compresses and decompresses audio and video data streams. The purpose of this type of codec is to reduce the size of digital audio samples and video frames in order to speed up transmission and save storage space. The goal of all codec designers is to maintain audio and video quality while compressing the binary data further. Lossy methods are widely used, which actually discard bits that most people cannot hear or see.

DRM (Digital Rights Management)
A system for protecting the copyrights of digital content that is distributed online. It may also include the accounting for paying royalties to the authors of the material. In the music world, a DRM system provides a container format that includes album and track titles and a set of rules for enforcing copyright compliance that software and hardware players must support in order to play back the material. Such systems can be configured for various distribution scenarios. For example, songs downloaded from a music service may only be played as long as the user maintains a subscription. Titles can be configured to expire after they have been played some number of times or on a particular date. Advanced audio coding (AAC) and Windows Media are two major formats that support DRM.

MP3 (MPEG Audio Layer 3)
An audio compression technology that is part of the MPEG-1 and MPEG-2 specifications. MP3 compresses CD-quality sound by a factor of roughly 10, while retaining most of the original fidelity; for example, a 40MB CD track is turned into a 4MB MP3 file.

MP3 VBR and mp3PRO
MP3 VBR (variable bit rate) is an enhanced format that adjusts the compression based on the complexity of the music. The mp3PRO format generates a file half the size of a comparable MP3 file, but maintains compatibility with many MP3 players.

Converting a digital audio track from a music CD to the MP3 format is called "ripping." Ripping software is available as a stand-alone program or a function in a software-based media player such as Windows Media Player 10.

WMA (Audio) and WMV (Video)
When Windows Media audio codecs are used, the resulting file is given a .WMA extension. When Windows Media video codecs are used, files have a .WMV extension. For non-Windows codecs, the .ASF file extension is used, and WMA and WMV files can be renamed with the .ASF extension for compatibility with earlier players.

PC Magazine - www.pcmag.com

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