Helping people with computers... one answer at a time.
Audio CDs are different from data CDs. Typically, your burning software needs to know how to create audio CDs, and you need to explicitly tell it to do so.
When I download music and then burn it to a CD, it comes out just fine. But, I cannot play the CD in my car's CD player. The music is almost always MP3. Is there a way I can convert the MP3 to play in my car? And what format are store-bought CDs?
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The CDs that you play on your computer and those that you listen to in a standard CD player, such as the one in your car, are formatted quite differently. And while you can play store-bought audio CDs in your computer, the CDs that you burn on your computer will usually not work in your car stereo or other audio CD player.
Why? Simply put, your car stereo is not a computer.
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Let's look at the two different formats first. Audio CDs are designed for one purpose: audio. They contain raw, uncompressed data, in a very fixed format: 44,000 samples per second, with each sample consisting of a 16-bit (2-byte) number for each of the right and left channels.
If you do the math, that's 176,000 bytes per second, or 633,600,000 bytes for an entire hour of audio.
If you've ever seen blank, 70-minute CDs, these hold roughly 740 megabytes of data - enough for about 70 minutes of sound in audio CD format.
Data CDs, on the other hand, hold anything. They're just another media on which you can store files from your computer. The format of a data CD is even similar to the format of your computer's hard disk. It has a file system, directories, folders and files.
But your car stereo knows nothing about file systems, folders and the like. All it knows is how to stream that raw audio data off of an audio format CD. While your computer can do that it too, it's also a general-purpose device that understands the format of a data CD.
But that's not the only difference. Remember that I said that an audio CD is uncompressed. Every second takes up 176,000 bytes, regardless of whether that's a second of a symphony, someone speaking, or just silence.
MP3 is a compressed format, like almost every other common audio format available for internet downloads and computer use. It uses compression technology to make the file much smaller. A second of silence, for example, is going to require less data than a second of complex sounds. When you play an MP3 file, the software you use decompresses the sound as it's played. The problem is your car stereo probably doesn't have a clue about compression or decompression.
So what do you do? If you want to create an audio CD that will work in regular CD players, you'll need to use audio CD burning software. I happen to use Roxio's Easy CD Creator. This automatically decompresses my MP3 files to the correct format for audio CDs. The trick is simply to select Roxio's "Music Disc Creator" program and click the Audio CD option as the type of CD you want to create. Other CD burning software will have similar options.
The catch is that the audio CD is uncompressed. While you might have been able to put seven or eight hours of MP3s onto a single data CD before, you're out of luck with an audio CD. These contain only about 70 minutes or so. It may take several audio CDs to hold what you might currently have on a single data CD.
The good news is that CD players are catching up. The ability to play MP3 files from data CDs has already appeared in car and home stereo CD players. And like a computer, these can play both audio and data CDs. Unfortunately, unless that functionality is built in, it's not something that can be added later.
Personally, what I want is a "Line In" port on my car stereo so I can hook up my portable media player (any portable media player, not just the iPod) and listen to my music without ever having to burn a CD at all. Maybe some day.
Article C2761 - August 19, 2006 « »
Leo A. Notenboom has been playing with computers since he
was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed.
After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers
to common computer and technical questions. More about Leo.
November 23, 2010 8:23 PM
I enjoyed the article and the comments, they were very informative as far as pointing me in the right direction for further investigation.
I think it would be helpful if you could update your response to this question with more information:
1. You provide a good description of the type of raw, uncompressed music data on commercial CDs. When you open a commercial music CD, it lists track numbers as .cda files of 1 KB size (hovering over a file shows there's only 44 bytes per .cda file). You could explain that these .cda files are merely indexing that provides access to the music tracks; the .cda file is not the actual music.
2. Some commenters have suggested that tracks on commercial music CDs are in .wav format; as you have explained in the comments, this is not the case. All of the "formats" are for using digital audio files on a computer-type device, and none of these are used on commercial music CDs.
3. What formats can be interconverted, what speed of burning can be used, which type of disk you can burn to (CD-R, CD-RW, DVD +-R, DVD+-R-DL, DVD-RW, etc.), and whether or not you can burn your files in Audio CD data so that it can be played on even old CD players, is determined by your audio file conversion and burning software, what function features are available with your disk burner hardware (i.e. what speeds it can burn or play and what types of disk media it can read/write to). The hardware, software and disk media have to be compatible before you can burn a CD that will play on any CD player.
4. The different audio formats might be discussed as well, including the pros and cons of the different "lossless" formats where there is little or no loss of music data in the ripping from music CD but you end up with very large music files, to the various compressed formats that may lose some of the music data (with a small but corresponding loss of music quality that depends on the Bit Rate selected), but ends up about 1/10 the file size of a lossless format or as audio CD data.
5. How much music you can put on a disk depends on whether or not the the music files are compressed, and the selection of a disk media that is compatible with your hardware/software. For example, you might be able to find commercial music CDs with around 20 songs (70-80 minutes of play) recorded as digital Audio CD data with associated .cda indexing files. With the proper harware and software, you can burn about the same amount of music in a lossless computer audio format. If you burn a compressed audio format file (i.e. MP3 at 192 Bit Rate which is high quality but not as good as lossless, where average song size is 5 MB) with a standard CD-R (700 MB), you can burn up to 140 songs. Burning the same MP3 files to DVD+-R DL disk media, you can theoretically record up to 1580 songs on a single disk.
6. The advantages of compressed music files seem to outweigh their disadvantages, and recommend upgrading your home and car audio systems to play CDs/DVDs with these files (i.e. MP3), or secure adapters for portable MP3 players to your various home and auto audio systems.
November 26, 2010 7:49 PM
All this technical stuff gives me a headache. All I need to know is which audio file format will play on a cd player and a car player.
The audio files formats that are currently on my hard drive are:- MP3, Windows media audio file (presumably WMA), MPEG-4 Movie, and WMA.
What's the go? Which audio file formats should I have on the CDs after burning the hard disk files.
I note your comments about letting the burning software do the job. I use Nero.
December 23, 2010 10:47 PM
I produced audio CDs for my car as above but still NoGo. Used Nero7premium, set for audio, created ".cda" files. Does CD-R, CD+R play any role? Is maybe ROXIO going to make a difference?
January 1, 2011 4:43 PM
All comments avoided the specific question which was "What format (not what conversion program) should I use to burn my Audio CDs?" I know at least one format that you could select and that is ".cda". How about ".flac" or perhaps there are other formats that will play???
January 2, 2011 11:36 AM
02-Jan-2011