The first format that was created for CDs was the audio CD. It was meant to succeed the vinyl record as a method for storing and playing music and was called the Compacy Disc Digital Audio. Cassettes and records were the primary methods of carrying audio, but they had problems that were addressed with the help of CDs. The quality of the vinyl on the record could degrade as you kept playing it back, which could lead to lower sound quality, which CDs fixed.
The "Red Book," so named because of the color that the cover sports, shows that the medium standard for your typical Compact Disc is meant to carry a frequency range of 20Hz to 20kHz, and two channel 16-bit PCM encoding is used to convey the audio, giving it a high standard for quality. While cassette tapes or records usually have monaural recordings, you could not do that with CDs, so mono tracks were just presented as two channels that sounded identical.
Though the Red Book Standard claims that you can use four channel sound, commercial CDs have not used this; instead DVD audio is usually the standard for that particular format. When CDs first came into prominence, they were resisted at first by music aficionados that touted the superior sound quality of vinyl, which is something that some people still hold to today. The origin of this belief stems from the fact that early CDs used the cost cutting measure of having 14-bit digital-to-analog converters in lieu of the usual 16-bit ones, but that is in the past. Though technology has caught up, the discussion still rages as to which is better, vinyl or CD.
Compact Discs
A CD is a format that uses an optical disc to carry data in a digital format. Sony and Philips created this particular format together in 1980; it was meant to replace the vinyl record and provide a more secure method of carrying data. As they first looked into creating this design, they wanted to look at a 60 minute playing time for that format. Norio Oga, the vice president of Sony at the time, thought about that particular time limit so it would fit the 1951 recording of Beethoven's Symphony #9. In later years, 80 minutes became the new time limit.
As the time passed, the format would expand and further itself, with CD-ROMS that could carry computer data to VCDs and SVCDs, which are video compact discs that could hold interactive media and photos as well, providing new ways to use the medium. Though the CD has been around for more than two decades, it is still the primary media for audio files.
CD-i
Interactive media uses this type of CD. This had audio on it, but the first track instead held extra information which would not be displayed on the table of contents for the CD. So when it was placed in a regular CD player, it would not play that track.
Though CD-i did not last long, it was used mostly for children's games and interactive coloring books.
CD-Text
The Red Book Standard also talks about CD-Text, which is a format that includes the audio tracks, along with text that provides the artist, track and album names. Though this feature is typical in most CDs now, there are some disks or hardware that does not use this. More and more new cars are including this feature in order to show data about your CDs. CD+Graphics (CD+G) and CD+ Extended Graphics (CD+EG/CD+XG)
These formats have data on the audio, both in text format and in picture format, so you have more data on your tracks. While they operate normally in regular CD players, if you have a unique player you will be able to see added graphical information. For the most part, karaoke machines use these formats to display the lyrics so you can follow along.
CD-ROM
When the CD first came out, audio playback was its only purpose. However, five years after its release, Philips and Sony thought they could use the same medium to display computer information. If you had a CD-ROM drive on your computer, you could play DVD-ROM disks.
Video CD(VCD) and Super Video CD (SVCD)
When the VCD and SVCD came out, they were the primary method of viewing video from a CD, and both DVD players and VCD players could use them. With VCDs, you could get VHS-level quality on the video, with improved visuals on the SVCD.
Picture and Photo CDs
Kodak developed the CD for use as a data storage medium to put your photos on, calling them Picture and Photo CDs. While they sound similar, there are significant differences in these two formats. With the Photo CD, you can hold 100 images of high quality images; the Picture CD, however, you can place far more images on them, but they are compressed JPEGs.
SACD (Super Audio CD)
This format is like the regular CD-DA, but the audio is at a much higher resolution, making the sound far better than a typical CD. With the advent of DVD-Audio, SACDs were created in order to combat its popularity, though the fact remains that DVD Audio did not catch on very well.
With an SACD, you will also be able to have a hybrid disc that includes both regular CD and SACD audio, giving you two options for quality on your tracks. That feature also permits you to play these SACDs in regular CD players and still hear the tracks.
CD-R (CD Recordable)
CD-Rs are CDs that have a photosensitive dye that the data spiral receives in the manufacturing process. The CD burner will then use a laser to alter the dye's color, imparting the information and giving it the ability to be played in a regular CD player, so its read laser can interpret the information.
While CD-R burns are intended to put the information on the disk forever, there is research that indicates, that the media will be unreadable over time. Though a physical CD can endure for up to a century, you might not have the same time frame with the information placed on it, due to the quality of the disk, how you store it, or how well the drive works. There are even tests that indicate an 18 month shelf life for burned CDs, especially if you do not take good enough care of your CDs.
CD-RW (CD Rewritable)
Compared to colored dyes in CD-R, CD-RWs use metallic allow to carry their information. When the write laser is used in the burner, the alloy is heated up in order to make the allow reflect the information on the disc. In this manner, it is turned into a typical CD and it can store the data.
Enhanced CDs
Enhanced CDs were utilized to put extra computer-related information onto an audio CD, thereby increasing the value of their music discs. If you had a CD-ROM drive, you could access unique features and data on your computer.
Once computers started to get more prevalent in the late 90s, more Enhanced CDs were created. Once Iron Maiden started to remaster their albums, they made their rereleases Enhanced CDs.
CD Recording
If you want to put data of your own onto a CD, there are many ways in which you can do it. There are CD-R, which necessitate making a permanent copy of your data, or CD-RWs, which allow you to rewrite and overwrite as you see fit.
DVDs
Much like a CD, a DVD, or Digital Versatile Disc, is a format meant to store digital data. It can store both video and audio, as well as normal computer information. Though DVDs and CDs may look nearly identical on the surface, DVDs have a much greater storage capacity. While CDs were expanded to provide a plethora of formats used for different purposes, DVDs have only yielded DVD Video and DVD Audio.
DVD-RAM
DVD-Random Access Memory is utilized mostly to back up data for computers in the event of an emergency. Compared to DVD writable and rewritable formats, DVD-RAM is far more efficient and durable due to the defect management capabilities and error control integrated into the medium. What's more, data can last much longer on a DVD-RAM, and has a greater capability of being rewritten than RW discs on the whole. If you want to store data for a long time, this is the preferred method.
DVD-R and DVD+R
Both of these formats are fairly similar in their purpose, but they do the same job in fairly different ways, making them quite dissimilar. They work not unlike recordable CDs in that dyes are used to store the information. Whatever the format, you are meant to put video or data onto the disk using these dyes; though they both do the same thing, they do so in technically different ways, though this is inconsequential to the typical consumer due to the compatibility of the formats.
Due to this lack of real difference between consumers, there is no clear winner on the market, so both formats are here to stay for right now, as the public has not decided on one or the other.
DVD-RW and DVD+RW
Users can rewrite data onto a DVD disc using one of these formats, which both perform the same function They act just like CD-RWs in that metallic alloys are the secret to recording this overwritable data to a DVD; also, just like with DVD-R and DVD+R formats, both formats are equally preferred and fairly identical, so there is no winner on that format. Since they are both compatible with burners and players of DVDs, no single format will win out.
DVD Audio
DVD-As or DVD Audio, is a method of fitting a DVD with high quality audio tracks. While this is a form of DVD, it is not meant to carry video, and carries few similarities. DVD-As do, however, allow you to have your music in a variety of formats from uncompressed mono to compressed 5.1 digital surround sound.
The year 2000 saw the release of DVD-As, where it started to compete with SACDs. In the end, both formats lost out to the lasting impact of the CD.
DVD Recording
You can also record with DVDs, much like you could with audio CDs; there are recordable formats that you can use to put your own data onto a DVD, such as DVD-R and DVD+R where you can write it once to a disc, or DVD-RW and DVD+RW where you can keep rewriting, not to mention DVD-RAM.
DVD Video
In this day and age, most people get their digital video media in the form of DVD. Japan brought out this product in 1996, and it started to dethrone VHS very rapidly. While Blu-Ray format is newer, it is still too expensive and not widespread enough to beat DVDs except in Japan.
With a DVD Video, you get MPEG-2 files that are compressed to fit a movie or television show, but the video quality is much better than a VHS. There are even features such as menus, chapters, subtitles and even featurettes and extra audio tracks you can add on.
