I just purchased a new car with a factory AM-FM/CD stereo. On the stereo was a sticker: “DO NOT PLAY CD/R OR CD/RW”. Being a person who burns his own CD’s, this is of concern to me. The salesman didn’t know the specifics, and the friends I’ve asked gave me some vague answers about how homemade CD’s “make the laser work too hard”. I’ve played a couple of my CD’s in it, and they sound just fine. But am I doing actual damage to the player? And if I decide to go with an after-market stereo, what should I be looking for to insure that I can continue playing my own CD’s?
And a related question: What exactly does it mean when a car stereo claims to “play mp3’s”? Is this different from home-burned audio CD’s?
I’m guessing the reason for the warning has to do with the thickness of the discs. If it’s a slot-load player, perhaps the manufacturer is worried that some cheap CD-R blanks will jam the player?
As for playing MP3’s, this means the player can play an MP3 file which is compressed, rather than only playing redbook audio CDs. The benefit of MP3s is that they are small files, and so you can put a lot on one CD. Dozens. The drawback is that MP3 is a lower quality audio format. How much lower depends on the bit rate it was encoded at.
I wonder if perhaps the manufacturer is worried about labels that people stick on homemade CDs. A slot loading player could definitely have problems dealing with a disc that has a large, sticky paper label on it. Could very well make the CD get jammed in there.
A basic sound format is the wave format, the file extension being .wav. This, essentially, is what is on your CDs. To give you an idea, an average three minute song is approximately 40-50MB in the wave format. The mpeg layer 3 encoding (mp3) takes the wave file and compresses it at some ratio. From what I’ve read, when two sounds enter the ear at the same time, the ear/brain only perceive the louder of the two sounds. MP3 encoding takes advantage of this fact and discards all of the “quieter” sounds. The bit rate (amount of data/sec) is what determines how much is thrown away.* Most home stereos and automotive head units are incapable of decompressing the mp3 format into wave format. Ones that are able to do so have the appropriate software (and a bit of RAM, I’d assume) to read and play mp3 files. What this means ultimately is that instead of 15 or 20 songs per disc, you can fit 200-300. It’s up to the user to figure out how to get to “Hootie and the Blowfish” when there are 150 tracks ahead of it on the CD.
*For example, 64kbps (kilobits per second) encoding compresses at a 22:1 ratio, and will result in a low quality, but small, audio file. A file encoded at 320 kbps is compressed at a 4.4:1 ratio. It will sound better, but will be much larger. My mp3s are all encoded at 128kbps. Many people prefer 160 or 192 kbps. I have nearly 4000 mp3s, so the difference in storage size is somewhat significant. Personally, the only time I ever really heard a difference between a CD and a 128k mp3 is when I was blasting them through a 6000 watt PA system during our set breaks at festivals and huge parties. The encoding tends to lose more of the low end, and the mp3s sounded a little flat when I really put some juice behind them. But for normal applications, it works just fine for me. YMMV.
I’m sorry, I didn’t really address the question. When you burn a normal audio CD from an mp3 library on a computer, your computer decompresses the mp3s before they are burned onto the disc. With an mp3 capable head unit, you can choose to burn the mp3s onto the disc without decoding, thus allowing many more songs onto the same CD.
As for your primary question, I’ll leave that one to people more knowledgeable than myself.
There is not enough information in your OP to give you anything but speculation. Different manufacturers might very well have different reasons for placing such a warning on their products. Most likely, however, the reason is merely one of technological compatibility rather than a risk of physical damage to the player or media. It has to do with how the CD tracks are read; car and many standalone CD players use a single-beam reading laser, which works just fine with factory-stamped CDs but can be problematic with CD-R and -RW media. See this article for more info. Bottom line: some CD-R or -RW media will read just fine, others won’t. I suspect that rather than deal with customer complaints, the manufacturer of your player included the warning sticker so people wouldn’t conclude there was a problem with the unit.
I’m sorry if my OP wasn’t clear–I guess my general question is whether or not I’m doing any damage to the unit itself. You seem to indicate that I am not. If anyone else has an opinion on this, I’m open to any input.
Sam Stone mentioned something about the quality of the media itself. I have noticed that some CD media is thinner than others–I didn’t realize that made a difference. Any recommendations on brands (since I can’t very well open the package to check)?
It’s hard to imagine how you could damage the unit by playing a CD-R disc. Many players won’t play CD-R or, more commonly, CD-RW, because of the different reflective properties of those discs, but that just means the disc won’t play - it’s no worse than putting a disc in upside down. The only danger I can think of is getting a disc stuck inside if the player doesn’t recognize that you’ve inserted a disc.
As far as brands of media, I’d say stick with whichever brand you were able to play in there. If it plays, there’s virtually no chance that it’ll cause problems.
And if you’re looking for an aftermarket player, I’d recommend finding one that says it can play CD-RWs (if it can do that, it can definitely play CD-Rs) and MP3 files, and also has an easily accessible line-in jack for future expansion (if you ever want to hook up an iPod, satellite radio, laptop, etc.).
It might be worth doing some research and reading reviews, too… my last car MP3 player didn’t have a resume feature for MP3s, so when I restarted the car it’d start the last track over from the beginning, and my current one’s fast-forward only goes at about 1.5x-2x normal speed for MP3s. Both of those misfeatures make it a pain to listen to recorded radio shows, but of course neither of them were mentioned on the boxes.