If you view the contents of a music CD from Windows, you'll see that it contains a number of .CDA files each corresponding to a song track. (CDA stands for Compact Disk Audio)
I regularly get letters from subscribers asking why can't they just copy these files to their PC rather than first having to rip them to .WAV, MP3 or other music files.
It's a good question with a simple answer: there are no .CDA files on a CD. In fact, from a Windows perspective, there are no "files" at all.
A music CD differs greatly from your hard drive in the way information is stored.
Computer hard drives store data in concentric rings called tracks. In contrast, music CDs store data in a continuous spiral starting from the inside of the CD and ending at the outer edge of the CD. Kind of like a vinyl LP in reverse.
The format of the data stored on CDs is also quite different; it's a continuous stream of raw digital data rather than a collection of individual files.
The reason the data is stored in this strange way is the music CD format was developed in the late 1970s long before the age of the home computer. CDs were designed to be played by specialised CD players and at that time nobody even considered that one day they would be played on a computer.
So what are .CDA files that you see on a music CD when you place a CD in your computer's CD tray?
These files are created by the Windows CD driver. They are simply representations of the CD audio tracks and are not actually on the CD.
Each .CDA file is a kind of a pointer to the location of a specific track on the CD and contains no musical information. CDA files are all 44 bytes in length and each contain track times plus a special Windows shortcut that allows users to access the specific audio tracks.
So if .CDA files contain no musical information, what happens if you "copy" a .CDA from an audio CD to your hard drive and then double click it?
If the CD is still in the drive then the corresponding track will play from the CD. If you remove the CD you will get an error message. That's because the .CDA file contain no music, it only points to where the music is located on the CD.
To work with music tracks on your CD you need first to convert them to .WAV, .MP3 or another file format that computers understand. That's what a CD ripper does and that's why you must use a ripper before you can work with your music files on a computer. Simple as that.
The good news is that you don't need to buy a CD ripper as you can find some excellent freebies here:
And if you want a free ripper that can handle both CDs and DVDs then check out this list:
But what about DVDs?
The DVD format was developed in the computer age so DVDs contain regular files just like those on your hard disk. That means they can simply be copied from the DVD to your computer.
So why do you need a DVD ripper?
The reason people use a DVD ripper is usually to remove copyright protection so that the movies or files on the DVD can be played on their computer. DVD rippers also commonly allow users to change video format and compress the data so the videos or movies can be played on the small screens of smart phones and tablets.
In other words CD and DVD ripping programs do rather different things:
CD rippers convert the raw digital data on music CDs into files a computer can read. They don't have to worry about copyright protection as most music CDs are not copy protected.
DVD rippers are designed primarily to copy files from the DVD and strip out copyright protection in the process.
If this is sounding complicated then rest easy. Combined CD/DVD rippers usually do both these things without you having to worry too much about it.
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