CDA stands for CD Audio.
You can play .cda files only from a CD-ROM. The tracks however, can be ripped to your HDD as a digital audio format like WAV, wma, or MP3 files.
A compact disc (or CD) is an optical disc used to store digital data, originally developed for storing digital audio.
A standard compact disc, often known as an audio CD to differentiate it from later variants, stores audio data in a format compliant with the red book standard. An audio CD consists of several stereo tracks stored using 16-bit PCM coding at a sampling rate of 44.1 kHz. Standard compact discs have a diameter of 120 mm, though 80-mm versions exist in circular and "business-card" forms. The 120-mm discs can hold 74 minutes of audio, and versions holding 80 or even 90 minutes have been introduced. The 80-mm discs are used as "CD-singles" or novelty "business-card CDs". They hold about 20 minutes of audio. Compact disc technology was later adapted for use as a data storage device, known as a CD-ROM.
The format of the audio disc, known as the "Red Book"/Sony standard, was laid out by Sony and Philips in 1981. Philips is responsible for the licensing program of the intellectual property pertinent to the Compact Disc including the "CDDA" logo that appears on the disc. In broad terms the format is a two-channel (four-channel sound is an allowed option within the Red Book format, but has never been implemented) stereo 16-bit PCM encoding at a 44.1 kHz sampling rate. Reed-Solomon error correction allows the CD to be scratched to a certain degree and still be played back.
The sampling rate of 44.1 kHz is inherited from a method of converting digital audio into an analog video signal for storage on video tape, which was the most affordable way to store it at the time the CD specification was being developed. A device that turns an analog audio signal into PCM audio, which in turn is changed into an analog video signal is called a PCM adaptor. This technology could store six samples (three samples per each stereo channel) in a single horizontal line. A standard NTSC video signal has 245 usable lines per field, and 59.94 fields/s, which works out at 44,056 samples/s. Similarly PAL has 294 lines and 50 fields, which gives 44,100 samples/s. This system could either store 14-bit samples with some error correction, or 16-bit samples with almost no error correction. There was a long debate over whether to use 14 or 16 bit samples and/or 44,056 or 44,100 samples/s when the Sony/Philips task force designed the compact disc; 16 bits and 44.1 kilo-samples/s prevailed. The Sony PCM-1610 and PCM-1630 are well known examples of PCM adaptors used in conjunction with the Sony U-Matic VCR.
How to rip CD to MP3, WAV, WMA.