Ah yes, the Compact Disc (or CD for short), is an optical disc for music, audio, and data storage.
It was released 30 years ago in 1982. During its creation and launch, the CD was poised to be the successor to vinyl. And while it did replace vinyl and cassettes as the format for nearly three decades, its primary focus shifted into a data storage medium over the years, especially it’s later years. With the CD-ROM and CD-Rs, compact discs went on to become much more than just an audio format. But all good things must come to an end, and unfortunately, the end for the CD came when mp3 players and music streaming services took the audio helm in the new millennium.To quote ABBA and bring this whole thing full circle, “Thank You For the Music” compact disc. Gone but never forgotten.
By the late 2000s, thanks in large part to the emergence of the MP3 in the early/mid 2000s, those shiny little discs began to see a steep decline in sales. And by 2015, only 24% of music sales in the United States were courtesy of the CD. Three years later, Best Buy, one of the leading CD retail sellers announced plans to significantly decrease focus on the sales of what was once the form of music entertainment. And while CDs are technically still being made today, and still continue to sell greatly, people are questioning if the CD is still relevant or not.
And the answer is yes.
Physical Media will still be a market and people WILL buy and prefer physical than digital.
Created by Phillips & Sony, the Audio CD format is a two-channel 16-bit PCM encoding at a 44.1 kHz sampling rate per channel with bitrate at 1.5 mbps. It has a capacity up to 74–80 minutes per disc and uses a red laser to read the disc's 650-700 MB storage data.
The stereo sound quality is good and clean (depending on the mastering). Four-channel sound has never been implemented. Monaural audio has no existing standard on a Red Book CD; thus, mono source material is usually presented as two identical channels in a standard Red Book stereo track (i.e., mirrored mono). Rarely, there are some CDs that have 2 hours of audio by splitting the left and right channels as separate audio streams.
A note, CDs are typically and always in stereo, but there are some that have "Dolby Surround" encoding. What's this? A Dolby CD? Is this related to Dolby Digital? No, Dolby Surround is Dolby Pro Logic, a Matrixing technology that adds additional audio channels (center and rear) encoded into the stereo tracks. Dolby Surround-encoded CDs were designed to be processed by Dolby Surround processor (compatible with Pro Logic systems). They stopped making them in the 1990s and they're compatible with normal CD players.
The first commercial compact disc was produced on 17 August 1982. It was a recording from 1979 of Claudio Arrau performing Chopin waltzes (Philips 400 025-2). Arrau was invited to the Langenhagen plant to press the start button.
The first popular music CD produced at the new factory was The Visitors (1981) by ABBA.
Some Blu-ray movies (and video games) will sometimes include a CD soundtrack as a bonus.
Sony’s CDP-101 first compact disc player went on sale in Japan on October 1, 1982, and retailed for the equivalent of around $674, which today would be around $1609. Fifty CDs were available at launch, priced between $14 and $15.25 apiece — roughly $33 to $36 today. Today, most mainstream CD albums are priced at $9.99 ($15 for collector's editions). CD players are alot cheaper now than back then and most (especially computers) allow you to rip CDs and store audio in the hard drive, and play them without the disc needed. Most BD/DVD players and computers allow CD playback.
Audio CDs are often used for music and audio productions (audiobooks and radio dramas).
Most CD albums are one disc and audiobook CDs are often in multiple discs because of the limited 74-80 min time capacity. Longer books, like Game of Thrones, will be in a 20-CD set.
When accessing CD data from computers, unlike on a DVD or CD-ROM, there are no "files" on a Red Book audio CD; there are only the physical pits and lands, which in turn represent a single encoded data stream, which ultimately represents one continuous stream of LPCM audio data, and a parallel, smaller set of 8 subcode data streams. Computer operating systems, however, may provide access to an audio CD as if it contains files. For example, Windows represents the CD's Table of Contents as a set of Compact Disc Audio track (CDA) files, each file containing indexing information, not audio data.
In a process called ripping, digital audio extraction software can be used to read CD-DA audio data and store it in files. Common audio file formats for this purpose include WAV and AIFF, which simply preface the LPCM data with a short header; FLAC, ALAC, and Windows Media Audio Lossless, which compress the LPCM data in ways that conserve space yet allow it to be restored without any changes; and various lossy, perceptual coding formats like MP3 and AAC, which modify and compress the audio data in ways that irreversibly change the audio, but that exploit features of human hearing to make the changes difficult to discern.
There are a few variants of the CD, that are mostly amendments to the Red Book standard. Many people, even music artists or sound engineers never knew these amendments, extensions, or variants existed.
MP3-CDs are CDs that contain the compressed MP3 format. Discs are written in the "Yellow Book" standard data format (used for CD-ROMs and DVD-ROMs), as opposed to the Red Book standard audio format (used for CD-DA audio CDs). Many modern CD players (mostly DVD/BD players) will play MP3-CDs, but not all players are compatible.
Because of audio data compression, optical discs do not have to spin all of the time, potentially saving battery power; however, decompressing the audio takes more processor time. The audio is buffered in random-access memory, which also provides protection against skipping.
The number of files that a disc can hold depends on how the audio files are encoded and the length of the audio. A standard audio CD (74 minutes) can hold about 18 audio programs, and a 650-MB data CD (equivalent to a 74-minute audio CD) containing mid-quality (160-kb/s) audio files can hold approximately 9.5 hours of audio or about 138 audio tracks.
ID3 tags stored in compressed audio files can be displayed by some players, and some players can search for audio files within directories on a compressed audio optical disc. ID3 is a metadata container most often used in conjunction with the MP3 audio file format. It allows information such as the title, artist, album, album art, track number, and other information about the file to be stored in the file itself.
Advantages of using MP3 instead of LPCM are
- Longer runtime as per file compression
- 6 red book audio discs for the price of one Yellow Book (CD-ROM), depending on file compression rates
- Longer battery life from fewer disc spins
- Discs marketed without "music" endorsement aren't rejected since Yellow Book mode (CD-ROM) is being used instead of Red Book audio mode.
This technology is most commonly used in audiobooks new on CD since 2000 or so. Especially since unabridged audiobooks can run many hours in length. CEA/APA has published the following standards on audiobooks.
- CEA-2003-C - Digital Audiobook File Format and Player Requirements
- CEA-2004, Audiobook Media and Player Compatibility.
CD-Text is an extension of the Red Book Compact Disc specifications standard for audio CDs. It allows for storage of additional information (e.g. album name, song name, and artist name) on a standards-compliant audio CD.
The CD-Text information is stored in the subchannels R to W on the disc. This information is usually stored in the subchannels in the lead-in area of the disc, where there is roughly five kilobytes of space available. It can also be stored on the main program area of the disc (where the audio tracks are), which can store about 31 megabytes. Since the R to W channels are not used in the Red Book specification of audio CDs, they are not read by all CD players, which prevents some devices from reading CD-Text information.
CD+G (also known as CD-G, CD+Graphics, and TV-Graphics) is an extension of the compact disc standard that can present low-resolution graphics alongside the audio data on the disc when played on a compatible device. CD+G discs are often used for karaoke machines, which use this functionality to present on-screen lyrics for the song contained on the disc. The CD+G specifications were published by Philips and Sony in an updated revision of the Red Book specifications.
The first CD to be released with CD+G graphics was Eat or Be Eaten by Firesign Theatre in 1985.
Check out the biggest archive of CD+G albums @ cdplusg.com/cdplusg/Main.html
CD+EG: Compact Disc + Extended Graphics (CD+EG, also known as CD+XG and Extended TV-Graphics[1]) is an improved variant of the Compact Disc + Graphics (CD+G) format. Like CD+G, CD+EG utilizes basic audio CD features to display text and video information in addition to the music being played. This extra data is stored in the subcode channels R-W. Very few, if any, CD+EG discs have been published. Specifications: 288 pixels per line, 192 lines, and, up to 256 colors.
CD-MIDI is a format used to store music-performance data using MIDI files which upon playback is performed by electronic instruments that synthesize the audio. Hence, unlike the original Red Book audio CD, these recordings are not digitally sampled audio recordings. The CD-MIDI format is defined as an extension to the original Red Book. There a very few players that play these kind-of discs, mostly computers will play these.
Video CD (VCD, View CD, and Compact Disc digital video) is a standard digital format for storing video media on a CD. VCDs are playable in dedicated VCD players, most modern DVD-Video players, personal computers, and some video game consoles. The VCD standard was created in 1993 by Sony, Philips, Matsushita, and JVC and is referred to as the White Book standard.
Overall picture quality is intended to be comparable to VHS video. Poorly compressed VCD video can sometimes be lower quality than VHS video, but VCD exhibits block artifacts rather than analog noise and does not deteriorate further with each use. It can only hold 80 minutes of video. It uses MPEG-1 for video and MPEG-1 Audio Layer II for stereo sound. The audio frequency range is limited to those sounds most clearly heard by the human ear.
352x240 (or SIF) resolution was chosen because it is half the vertical and half the horizontal resolution of NTSC video. 352x288 is similar to one-quarter PAL/SECAM resolution. This approximates the (overall) resolution of an analog VHS tape, which, although it has double the number of (vertical) scan lines, has a much lower horizontal resolution.
Unlike DVDs, it has no menus. Only the basics, like chapters.
Today it's still popular, mostly in Southeast Asia, Africa, and India, because of the very low consumer price.
Super Video CD (Super Video Compact Disc or SVCD) is a format used for storing video media on standard compact discs. SVCD was intended as a successor to VCD and an alternative to DVD-Video and falls somewhere between both in terms of technical capability and picture quality.
SVCD has two-thirds the resolution of DVD, and over 2.7 times the resolution of VCD. One CD-R disc can hold up to 60 minutes of standard-quality SVCD-format video. While no specific limit on SVCD video length is mandated by the specification, one must lower the video bit rate, and therefore quality, to accommodate very long videos. It is usually difficult to fit much more than 100 minutes of video onto one SVCD without incurring significant quality loss, and many hardware players are unable to play video with an instantaneous bit rate lower than 300 to 600 kilobits per second.
It uses MPEG2 for video and MPEG-1 Audio Layer II for stereo sound.
The SVCD standard supports several other features, including interactive menus, hyperlinks, karaoke lyric highlighting, four selectable overlay graphic subtitle streams, chapters, playlists, and DVD-quality still images/slide shows, along with audio, with a resolution of 704x480 (NTSC) or 704x576 (PAL/SECAM).
Although SVCDs proved more sophisticated than VCDs, the format remains in the latter's shadow.
Photo CD is a system designed by Kodak for digitizing and storing photos on a CD. Launched in 1992, the discs were designed to hold nearly 100 high-quality images, scanned prints, and slides using special proprietary encoding. Photo CDs are defined in the Beige Book and conform to the CD-ROM XA and CD-i Bridge specifications as well. They are intended to play on CD-i players, Photo CD players, and any computer with suitable software irrespective of the operating system. The images can also be printed out on photographic paper with a special Kodak machine. This format is not to be confused with Kodak Picture CD, which is a consumer product in CD-ROM format.
Read more about it here.
CD-i or Compact Disc Interactive. Yes, we know what you're thinking, that God-awful Zelda games that turned into internet memes. But that ruined the reputation of this underrated CD variant that wasn't just designed for 2D games. The Philips Green Book specifies a standard for interactive multimedia compact discs designed for CD-i players (1993). CD-i discs can contain audio tracks that can be played on regular CD players, but CD-i discs are not compatible with most CD-ROM drives and software. The CD-i Ready specification was later created to improve compatibility with audio CD players, and the CD-i Bridge specification was added to create CD-i compatible discs that can be accessed by regular CD-ROM drives.
Today you can easily play these CD-i games on a computer using emulation and there is a homebrew community making CD-i games for the format. theworldofcdi.com/open-source/cd-izi-authoring-tool/
CD-ROM: For the first few years of its existence, the CD was a medium used purely for audio. However, in 1988, the Yellow Book CD-ROM standard was established by Sony and Philips, which defined a non-volatile optical data computer data storage medium using the same physical format as audio compact discs, readable by a computer with a CD-ROM drive.
This is very different from CD-i.
Until the mid-2000s, CD-ROMs were popularly used to distribute software for computers and video game consoles. Some CDs, called "Enhanced CDs", hold both computer data and audio with the latter capable of being played on a CD player, while data (such as software or digital video) is only usable on a computer (such as ISO 9660 format PC CD-ROMs). These is called Mixed Mode CDs.
Today, many of the older CD-ROM computer games can be played on Windows and Linux using virtualization and emulation.
There are some publishers that still publish CD-ROM games.
Here's a list of CD games that uses Mixed Mode.
CD Plus is a format that combines audio tracks and data tracks on the same disc by putting audio tracks in a first session and data in a second session. It was developed by Philips and Sony, and it is defined in the Blue Book. Basically, the same thing as Red Book mixed mode CDs.
DDCD (Double-density compact disc) is an optical disc technology developed by Sony using the same laser wavelength as a compact disc, namely 780 nm. The format is defined by the Purple Book standard document. For a 120 mm disc, it doubles the original 650 MB to 1.3 GB capacity of a CD. It was considered a failure and there was no point. Basically the same thing as an SACD. The technology failed to acquire a significant market share before the success of DVD technology. The DVD technology offered a significantly higher capacity (four times more initially with 4.7 GB on single-layer discs, 8.5 GB on dual-layer discs to a max of 17.08GB on a dual-side+dual layer disc).
Super Audio CD (SACD) is a high-resolution read-only optical audio disc format that was designed to provide higher fidelity digital audio reproduction than the Red Book. Introduced in 1999, it was developed by Sony and Philips, the same companies that created the Red Book. SACD was in a format war with DVD-Audio, but neither has replaced audio CDs. The SACD standard is referred to the Scarlet Book standard. It uses the Direct Stream Digital Format (DSD). DSD differs from LPCM, DSD is 1-bit, has a sampling rate of 2.8224 MHz, and makes use of noise-shaping quantization techniques in order to push 1-bit quantization noise up to inaudible ultrasonic frequencies. This gives the format a greater dynamic range and wider frequency response than the CD.
Unlike CD, it offers surround sound, and more play time with 4.5 to 8.5 GB storage space.
Titles in the SACD format can be issued as hybrid discs; these discs contain the SACD audio stream as well as a standard audio CD layer which is playable in standard CD players, thus making them backward compatible. Most SACD releases are hybrid discs to gain more sales. Having made little impact in the consumer audio market, by 2007 SACD was deemed to be a failure by the press. A small niche market for SACD has remained, serving the audiophile community
Vinyl Disc is a hybrid of a standard audio CD and a vinyl record. The vinyl layer on the disc's label side can hold approximately three minutes of music.
So is the CD still relevant? Let's see.
CD Yes, the LPCM still sounds good today and you can add extra mix mode stuff to increase value.
CD-Text Yes, it's a great extension to know what song your listing to.
CD+G Yes, it's a cool feature for karaoke, lyrics, and artistic 8-bit visuals.
CD+EG Yes, but rarely used.
VCD No, we have Blu-ray and DVD. The picture and sound quality aren't as good. Unless it's an extra for album CDs using mix mode.
SVCD No, it's neat but despite 50% better PSQ, it requires more discs for a single movie. Unless it's an extra for album CDs using mix mode.
SACD Yes, despite having the greater capacity and DSD surround sound. It's a niche extra.
CD-i Yes. (not biased) It has potential despite being old and isn't OS-specific, unlike CD-ROM.
CD-MIDI Yes. It has extremely low kilobyte storage and can be used as an extra for mixed-mode CDs.
MP3-CD Yes. Mostly used for long audiobooks, but can be added as an extra to a normal album CD.
Photo CD No. Unless you're using it as a slideshow for school, business or a funeral. It's neat, but most people use USB or other devices.
CD-ROM Yes. People still play PC games on Windows and Linux. It should be for used for small games.
CD+ No. It's the same thing as Red Book mixed-mode CDs. It is unknown if any were made or compatible.
DDCD No. It's the same thing as SACD and DVD. So, there's no point.
VinylDisc Yes. Despite only holding 3 minutes of analog sound, it's a nice extra.
Yes, the Compact Disc is mostly relevant. You can add CD + Text + Graphics + MIDI + MP3, making it a great combo for albums or audio productions. Like this album here.
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