The purpose of CDA files is to help the computer play the compact disc. Files with the .cda extension contain a small amount of data (44 bytes) and serve as an index for tracks on an audio CD. Each CDA file follows the naming convention “Track##.cda.” In line with the “Red Book” industry standard, CDA files are the standard format for encoding audio on compact discs.
It is important to note that on a CD, files with the .cda extension do not contain the actual audio stream. Instead, they simply include the location of the beginning and end of the named track. Thus, CDA files can only be played when the CD is physically present in the CD drive. Various media players can open CDA files, such as iTunes, Microsoft Windows Media Player, VLC media player, and other Mac, Windows, and Linux audio players.
To confuse matters, however, some ripping software programs will assign .cda filename extensions to tracks that have been ripped (copied) from a CD onto a computer.
The actual audio format used on CDs is known as pulse-code modulation (PCM). PCM captures analog waveforms using an uncompressed, digital sampling technique that results in a very accurate digital representation of the original analog wave. As mentioned above, a track ripped to a computer as an audio CDA file is actually a PCM file that has been assigned a .cda extension.
Compressed vs. Uncompressed Files
Although the quality of a CDA file containing an uncompressed PCM stream is extremely high, it takes up a lot of space and will not be recognized by most portable digital media players designed for use with compressed files.
How to Convert CDA Files
Using a computer, converting a PCM or CDA file to a compressed format such as MP3 or WMA is very straightforward. Microsoft Windows Media Player is one of the most popular programs used to rip CDs onto the computer. By default, Windows Media Player converts the tracks into WMA files, although you can choose other formats. You can also use Windows Media Player to select the destination folder for your files.
Similarly, iTunes allows users to import CDs and convert CDA files to MP3s. VLC media player is another popular choice for ripping a CD to MP3s on the computer, especially as it is free, cross platform, and open source.
Some ripping software will allow the user to choose a format before ripping, eliminating the need to convert the files afterwards. However, many people prefer to archive music in an uncompressed format (such as a WAV or AIFF file), and then create compressed files from these high-quality originals.
The advantage of using compressed files on portable devices is that many more tracks can be stored with limited memory. On the other hand, uncompressed files are recommended for burning CDs for car stereos, home stereos, and surround sound systems.
Compressed Files: Lossless Formats
There are two classes of compressed files: lossless and lossy. As the name implies, lossless formats compress files without any loss of quality. These files are still rather large and many portable audio players do not support them.
Lossless compressed formats include:
- Monkey's Audio (APE)
- Apple® Lossless (also known as ALAC or ALE)
- Windows® Media Audio Lossless (WMA Lossless)
Compressed Files: Lossy Formats
By leaving out some data, lossy formats sacrifice a little quality for a much smaller file size. The loss of quality is not particularly noticeable on portable devices that use earbuds or small portable speakers for output. Audiophiles aside, many people cannot tell the difference between a lossy file played on a portable device and its PCM or ripped CDA file counterpart.
Lossy formats include:
- Windows® Media Audio (WMA)
Once the tracks from a CD have been copied and saved onto the computer in MP3, WAV, or a similar format, they can then be transferred to portable media players, smartphones, or burned onto another audio CD.