CD, CD-R, SACD, and DVD-Audio Glossary
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Analog record level control
CD-R/RW decks with this feature let you adjust the volume level when recording from analog sources such as LP, tape, and radio. For anyone who makes compilation CD-Rs from a variety of these sources, this control is especially important because it helps you maintain consistent volume from song to song.
CD-R (audio and data)
CD-Rs are recordable CDs that can be written to (i.e., recorded upon) once. When an audio CD-R has been recorded and finalized, the disc can be played like a regular CD in all home, car, and computer CD drives. However, a CD-R can never be re-recorded. CD-Rs commonly hold 80 minutes of music, though some discs today can hold as much as 99-minutes of music.
CD-Rs are designated for either "audio" or "data" use. Blank discs labeled "audio" can be used with home CD recording decks as well as computer CD-R/W drives, and cost more than data-grade CD-Rs. Blank CD-Rs designated as "data" tend to cost less than audio CD-Rs, but can only be recorded to using a computer CD-R/W drive.
CD-RW (audio and data)
Unlike CD-Rs, CD-RWs are rewritable CDs that can be written and rewritten to many times. When you make a recording on an audio CD-RW and finalize it, you can play it in many standard CD and DVD players. But when you want to change the disc's contents, you can erase it and re-write to it — from 30 to 50 times.
Otherwise, CD-RWs are fairly similar to CD-Rs. They commonly hold 80 minutes of music; some discs today can hold as much as 99 minutes. However, keep in mind that they are not compatible with as many kinds of CD players, especially older ones.
CD-RWs are designated for either "audio" or "data" use. Blank discs labeled "audio" can be used with home CD recording decks as well as computer CD-R/W drives, and cost more than data-grade CD-RWs. Blank CD-RWs designated as "data" tend to cost less than audio CD-RWs, but can only be recorded to using a computer CD-R/W drive.
Another name for a component CD recorder. The designation "CD-R/RW" indicates that such decks can record and play back both CD-Rs and CD-RWs.
Players with CD Text display will show disc, track, and artist names for all CD Text-encoded discs. This information is typically displayed on the player's front panel, although some models also display it on an LCD remote or on your television screen. A CD-R/RW deck with CD Text entry lets you encode titles and artist names onto any CD-R you record, prior to disc finalization.
The digital-to-analog converter (DAC) converts the numeric values stored on a CD into a series of voltages, which then produce the audio signal we hear. Most CD players use 1-bit D/A converters; some CD models (and most DVD players) use multi-bit converters. Both kinds of DACs provide excellent sound quality.
The two most common types of digital output are optical and coaxial. Optical digital connections require an optical digital cable. Though coaxial digital connections use standard RCA-style jacks, a coaxial digital audio cable designed specifically for the wider frequency bandwidth of digital signals is recommended.
Digital record level control
CD-R/RW decks with this feature let you adjust the volume level for digital recording. This is a great feature for anyone who makes compilation CD-Rs from various CDs, because it helps you keep the volume consistent from song to song.
(Note: If you've got a deck with only analog record level control, you can use this to adjust levels for digital sources, too, but you'll sacrifice a small amount of sound quality in the translation from digital to analog and back to digital.)
Direct disc (or track) access
Just push a button for instant access to any disc (or song). To hear or program track 7, just push "7". This feature can be accessible from the unit's front panel, the remote, or both.
One loaded disc keeps playing while you change other discs in the player.
You enter names for your discs; the names then display on the player's front-panel display.
DSD (Direct Stream Digital)
Direct Stream Digital (DSD) is the advanced recording technology that makes SACD possible. Standard CDs use 44.1kHz/16-bit PCM (44,100 samples-per-second Pulse Code Modulation, encoded at 16-bit resolution) to represent audio in digital form. DSD, on the other hand, is a 1-bit technology that samples music 2.82 million times per second, capturing 4 times more information. The resulting sound is warmer, smoother, and more "analog" than anything 44.1kHz/16-bit PCM can deliver.
A DualDisc is a two-sided disc that combines audio on one side with a DVD on the other side. The audio side carries stereo music, while the DVD side usually offers a multichannel version in Dolby Digital, DTS, or DVD-Audio in addition to video footage. Extras can include lyrics, documentaries, interviews, photo galleries, and more.
A DualDisc will probably play in most CD or DVD players. However, since DualDisc is slightly thicker than regular CDs, it may get stuck in some slot-loading players, or the DVD side may get scratched. A number of consumer electronics manufacturers have posted advisories regarding these issues, including Denon, JVC, Onkyo, Sony, and Toshiba.
Keep in mind, if the DualDisc has DVD-Audio content on the DVD side, you'll need a DVD-Audio-capable player in order to listen to that portion of the disc. Even if you don't have a DVD-Audio player, most discs will have a multichannel Dolby® Digital mix in addition to DVD-Audio, so that they can still be played in a regular DVD player.
A music-oriented DVD format that can carry up to 6 channels of 96kHz/24-bit audio (music for 5.1-channel home theater systems), or 2 channels of ultra high-resolution 192kHz/24-bit audio. Most DVD-Audio discs also carry lower-resolution Dolby Digital or stereo soundtracks for playback on DVD players that lack DVD-Audio decoders. A DVD-Audio disc may also contain liner notes, lyrics, menus, and still pictures that display on your TV. DVD-Audio uses MLP compression.
Refers to the range of frequencies the player is capable of reproducing. The human ear responds to frequencies from approximately 20 to 20,000 cycles-per-second, or Hertz.
Some CD recorders include a separate CD play-only well (or multi-disc changer), for convenient internal dubbing from CD(s) to CD-R/RW. Models with 2X or 4X high-speed dubbing let you copy an entire disc in half or a quarter the time.
Some CD-R/RW decks include a mic input that lets you plug in a microphone and record your own voice or instrument to CD.
Most CD-R/RW dubbing decks with a mic input also feature mic mixing. This allows you to mix the sound from a microphone together with the playback of a CD in the deck's playback well, and record the combination onto a blank disc in the record well.
Some decks with mic mixing also allow you to mix the mic input with a source connected to the CD-R/RW deck's line input, or to mix the sounds of a CD in the playback well and line input sound.
MLP (Meridian Lossless Packing)
A lossless compression technique (used on DVD-Audio discs) that removes redundancy from PCM audio signals. MLP achieves a compression ratio of about 2:1 while allowing the signal to be perfectly re-created by an MLP decoder.
Multiple CD player control
Lets you link your CD player to other compatible CD changers from the same manufacturer in a series and control them.
Some jukebox-style CD changers let you group discs (by artist, type of music, a family member's favorites, etc.) for playback.
Peak level search
Especially useful for recording, peak search scans the disc, finds the loudest passage, and then plays it back repeatedly so you can set record levels. It typically takes about a minute to scan a CD.
PCM (Pulse Code Modulation)
A signal sampling and transmission standard which is used by numerous digital audio formats. Standard CDs employ PCM at a sampling rate of 44.1KHz, encoded at 16-bit resolution.
A memory feature found mainly in multi-CD changers. If you choose, the changer can store a portion of a CD's "table of contents" — including its unique identification information. This means that whenever you play this particular disc, the changer will recognize it.
Also, many models let you create and store titles for the discs loaded in the changer. "Jukebox"-style changers often allow you to classify and store your music in categories like Rock, Jazz, etc. for easy group playback (see "Music groups" above).
A few CD and CD-R/RW decks let you increase or decrease the playback speed in precise increments — a great feature for DJs, musicians, and dance instructors.
Standard track programming lets you pick which songs you want to hear. Program delete takes a shortcut, letting you simply delete the songs that you don't want to hear.
Enables playback of the tracks on a CD (or in the case of some CD changers, tracks on multiple discs) in a random order selected by the player or changer.
Although SACDs look the same as standard discs, they can hold much more digital information than regular CDs. All SACDs contain a studio-mixed, high-resolution stereo signal, and many also contain a high-resolution surround sound signal, which can carry up to six independent channels. SACD uses a process of sound recording and reproduction called Direct Stream Digital™, or DSD, instead of standard PCM.
When an analog-to-digital converter digitizes an analog audio signal, it rapidly samples (or takes "snapshots" of) the analog signal's amplitude at regular intervals. These amplitude measurements are then converted to binary digital data — 1s and 0s — for storage on a CD or other digital audio medium.
The sampling rate (or frequency) is the number of samples taken per second. The standard sampling rate for CD is 44.1kHz — that's 44.1 thousand snapshots per second.
Sampling rate converter
Converts incoming digital source signals at other sampling rates to the CD-standard 44.1kHz. Most of our CD recorders offer this feature, which gives you more options when recording from digital sources. In addition to 44.1kHz sources like CD and MiniDisc, you can make direct digital recordings of DAT material at 32kHz or 48kHz, or digital satellite audio at 48kHz.
CD recorders with a sample rate converter bypass let you make a bit-for-bit perfect copy of any 44.1kHz audio disc — even DTS or HDCD.
Skip track ID
CD recorders with this feature enable you to encode, prior to disc finalization, Skip IDs for tracks containing recording mistakes or unwanted material. When you play the disc back in the CD recorder itself, the tracks you have designated will automatically be skipped.
(Note: Some, but not all, standard CD and DVD players will support this feature when playing back discs recorded with Skip IDs; others will play back all tracks on a disc, regardless of Skip IDs.)
The measure of the musical signal relative to background noise. The higher the S/N ratio, the cleaner the sound.
Lets you program a sequence of songs for playback in any order.
Variable line outputs
If a CD player lists "remote with volume control" as a feature, that means it has variable line outputs — you can use the remote to adjust the volume level of the signal coming from the CD player itself. This feature is especially helpful for applications where the receiver or amplifier doesn't have its own remote control.