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ATPM 7.02
February 2001


How To



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How To

by Evan Trent,

Playing Compressed Sound on a Home Stereo


I know that you can convert MP3s into WAVs and AIFFs, but they are both very large formats. I am wondering whether there are any other formats that you can convert MP3s into, which are more compressed but are still playable in most home stereos.


The AIFF file format supports several compression algorithms. They are all lossy. Your choices are MACE, Law, and IMA. AIFF files compressed with these compressors will play back fine on any computer or home stereo. The size of the files will be significantly reduced, but their sound quality will be adversely affected. You will have to play around to see if you are willing to accept the compromise. You can compress an AIFF file using one of these algorithms with a program like SoundEdit 16 from Macromedia, or using QuickTime Player under QuickTime Pro (you will need to upgrade if you are using the free version of QuickTime).

In my opinion it makes more sense to just burn out the MP3s directly to an audio CD using Toast 4.x. This will result in a CD that is playable on a home stereo, and the sound quality will be no worse than the MP3 source file, although you will not be able to fit as many songs on the CD as if you converted and compressed the AIFF files beforehand. Toast 4.x converts MP3 to AIFF on the fly but it does not offer the option to compress the AIFF files because that is too processor intensive to do on the fly and would interrupt the CD burning process.

Compressing AIFF files beforehand is time consuming. You can use a program like Cleaner from Terran Interactive to batch convert/compress files, but otherwise you have to baby-sit the computer and do it file by file. I’m lazy and would rather have more CDs with higher quality sound that required less of my time and energy to generate, than fewer with poorer quality sound.

A home stereo cannot play AIFF files that have been compressed using a proprietary or third party compression algorithm (or codec); it can only play AIFFs compressed using the algorithms that are part of the AIFF definition (MACE, Law, IMA, etc.). Files compressed using these algorithms do not need special software to be played because they do not fundamentally alter the file format; they simply tweak the dynamic range and save space in clever ways.

Proprietary algorithms (such as QDesign Music 2, which comes with QuickTime Pro, and is a remarkable compression technology) work their magic by way of far more sophisticated and successful methods, but in order to play the files you need a program that can read the new, modified, data. So using QDesign as an example, you would need to play the compressed files on a computer with QuickTime Pro (or the QDesign codec) installed, and naturally your CD player could not play a CD full of QDesign compressed AIFF files. In this sense they are no different than MP3s.

No matter what compression algorithm you use on the AIFF files in question, you are compressing the data for the second time (first time was with MP3), and that is always going to wreck the sound quality of your recording.

Also in This Series

Reader Comments (31)

Tomas Jones · February 16, 2001 - 01:01 EST #1
We have a Raite DVD/CD/MP3 player on our stereo system. This allows playing of MP3s on CD in our home system. I have an Aiwa CD/MP3 system in the car. I can do the same there. One CD holds 10 hours of music. I carry 5-6 CDs with me. Rock, Jazz, Blues, Comedy, Classical, Old Time Radio shows. Works great for long road trips.

James Funck · February 16, 2001 - 01:01 EST #2
How about a stereo receiver with a USB or firewire port? Jobs says that he wants the Mac to be the digital hub, but I don't want to watch DVD movies on my iMac (the screen is too small). I want to watch them on my TV. Why should I have to buy another DVD player when I have one in my iMac? I would also prefer to listen to iTunes and my MP3 files on my home stereo versus the iMac (better speakers). Sound sticks and an iSub are fine in my home office, but not in my living room. I know I could burn CDs and carry them downstairs, but why should I have to? The iMac plays CDs fine. Make the receiver AirPort compatable and we are rockin'!

So, how about it, Steve? You want to sell products to the millions of Wintel users. Apple would convert them all with a stylish 60-watt digital receiver that would allow iTunes, Quicktime, and everything else to integrate with my other consumer electronics. I'd pay $400-500 for one.
Mel Sanders · February 17, 2001 - 01:01 EST #3
Another, and, in my opionion, more efficient, method of enjoying your MP3s on a home stereo is to simply hop over to Radio Shack and buy a mini audio to RCA cable and run it from the audio output (where you normally would hook up your speakers or headphone on your Mac) to an available auxillary input on your stereo reciever (tape 1, tape 2, etc...). I do this and it works and sounds fantastic! I just use iTunes to set up playlists and, with my extensive MP3 collections, I have hours of music playing from my computer to my stereo without wasting any CD-R media.
Evan Trent (ATPM Staff) · February 18, 2001 - 01:01 EST #4
You have all made very astute remarks and they are all indeed correct. I would just like to clarify that this article was originally written as a response to an e-mail asking how to play MP3s on a stereo system (without the use of a computer) which cannot decode MP3s. It is for this reason that I avoided getting into issues of connecting computers to Hi-Fis or using MP3-capable CD decks in home stereo. Based on your responses, I can see that our readers are resourceful and on the cutting edge! As a result, I have decided to run a second installment which will discuss some of these alternatives. Stay tuned and thanks for reading.

Bob Smith · April 25, 2002 - 23:16 EST #5
I changed a WAV to an AIFF and burned it to a CD using Direct CD, but it didn't play on any of my stereos. What should I do? Will I need to compress the files?
Evan Trent (ATPM Staff) · April 25, 2002 - 23:22 EST #6
When you say youre stereo won't play the CD, do you mean that they don't recognize the CD or that they do recognize it but cannot play it--or is the sound messed up? If you could define the problem more specifically, I might be able to help.
Lee Bennett (ATPM Staff) · April 26, 2002 - 01:39 EST #7
Bob - first thing that comes to my mind (I see this mistake rather often) is perhaps you burned the CD in a computer volume format (such as HFS or ISO 9660) instead of regular CD audio format. If you put the CD into your computer instead of the stereo, what happens? Do the files just appear as Track 01, Track 02, etc. or do you see 'filename.aif' type items? It should be the Track 01... if your stereo is to play them.
Nick D. · September 8, 2002 - 22:47 EST #8
I just bought a new car stereo and it says it has an MP3 decoder built in. They also say that I can fit about 70 MP3s on one CD, put them in folders, and play them on my player. I would imagine that this would mean the files must be compressed. If you can help me with away to fit all these MP3s on one CD and still be able to play them, please e-mail me. I appreciate the help. Thanks!

Nick D.
Evan Trent (ATPM Staff) · September 8, 2002 - 23:02 EST #9
Stereo components with MP3 decoding can read CDs burned in ISO 9660 format with MP3 files on them. You can make these with Toast or any other CD burning suite. When the car stereo spec sheet states you can fit 70 MP3s on one CD, that number represents an approximation based on average song length and compression rate. The higher the bit rate, the larger the resulting MP3 file. So if you want to fit more songs on one disc, use a lower bit rate. If you set up all the MP3s with title, track, artist, and genre flags, the car stereo ought to display that information on its display too.
Misty · February 23, 2003 - 22:30 EST #10
I wanted to know how you fit 10 hours of music on to one disc. I have a computer full of MP3s, but when I burn them onto a disc, it will only hold 80 minutes worth.
Lee Bennett (ATPM Staff) · February 24, 2003 - 09:55 EST #11
Misty - check the settings in your CD burning software. Apparently, your current configuration is converting the MP3s to standard CD audio, thereby only giving you 80 minutes of music. You need to change the settings to burn an MP3 disc (the technical name is a disc burned in ISO 9660 format) instead of a redbook audio disc.

Please note that the drawback of doing this is that the MP3 disc will not play in many home CD audio players—only computers and some of the newer CD players that will read MP3 discs. In anticipation of a follow-up question, I will go ahead and answer that if you have one of the less recent CD players in your stereo that does not read MP3 discs, then you will not be able to use it to play a disc with 10 hours of music on it. It will only play the 74- or 80-minute standard audio discs.
Dave Ng · March 28, 2003 - 23:47 EST #12
The CD-Rs I burned on my computer's CD writer cannot be played at all on my car stereo, but can play in my home stereo. On the few occasions (and that's very rare) it can be read by the car stereo, some track either terminates halfway through or I cannot skip through the tracks. I have tried a few brands of CD-Rs and different burn speeds, but to no avail. Can you help me on this? I use an HP Writer and burning software and my car stereo is a Sony brand.
Evan Trent (ATPM Staff) · March 28, 2003 - 23:54 EST #13
Dave - typically this means that you are burning your CDs too fast. Slow down the burn speed to 4x and you should be fine. If that still causes problems try 2x but usually 4x works well. Some car CD players have very weak lasers and are easily confused by CD-Rs burned at high speeds. The other thing you might try is higher quality blank CD-Rs. If you are using a real bargain basement grade of CD-R media, sometimes that is the problem. I would try burning slower first and, if that still doesn't solve the problem, go out and get some better CD-Rs and see what happens. With better media, you can often burn at higher speeds and still playback on flakier CD players such as those in cars.
Lee Bennett (ATPM Staff) · March 29, 2003 - 12:10 EST #14
While I'm not exactly thrilled to counterpoint what Evan says on this kind of topic, I do so only because Dave has already mentioned he has tried different burn speeds and different discs.

The input that I'll add is to find out the age of the car stereo. Anything sold in recent years should have no problem with CD-Rs, but it's also been demonstrated that some of the earlier car CD players don't do well with CD-Rs of any brand or burn speed.

There's one idea that popped in my head, but I'm sure it's not the issue because Dave said he has been able to play a little bit of some CDs. But just to cover all the bases, here's what I wondered: I take for granted that you're not burning MP3 discs and it just happens that your home CD system can play them (some of the newest systems can) and your car player cannot.
Sammy · April 28, 2003 - 18:05 EST #15
Hi. I have an MP3-compatable car stereo. When I burn my music, I have no problem playing on it whatsoever.

But, having learned that I could possibly have a lot more tracks on a single CD using the ISO 9660 format, my car stereo does not play any sound.
Lee Bennett (ATPM Staff) · April 28, 2003 - 18:36 EST #16
Sammy - are you saying you previously burned standard audio CDs? All you should have to do is burn MP3 files in ISO 9660 format (be sure to have the .mp3 extension on the end). Many CD burning applications include an "MP3 Disc" format which you will want to use. Not only does this use the ISO 9660 automatically, but also generally properly configures the format since ISO 9660 can be burned in slightly different flavors.
Sammy · May 1, 2003 - 09:11 EST #17
I did previously burn standard audio CDs as you say, but when I burn them with "MP3 Disc" or in "ISO 9660" selected, this is when I get no sound. The files also end in .MP3.

Please, please help. Thanks.
Lee Bennett (ATPM Staff) · May 1, 2003 - 15:38 EST #18
Sammy - what model and brand is your car stereo? Perhaps I can help you be certain your stereo will actually recognize MP3 discs. If you are burning MP3s to an ISO 9660 disc, an MP3-compatible player would be able to read it. The only things I can think of that it would be is either that your stereo actually does not read MP3 data CDs, or perhaps your MP3s are encoded with variable bit rates which many MP3 CD players don't work with. I have an MP3 disc with two variable bit rate MP3s. All the songs play fine in iTunes, but those two tracks won't play on my JVC.

What brand/model is your player?
Nikki grattan · December 23, 2004 - 23:59 EST #19
I have a sony stereo that I just bought six months ago, it has always played burned CDs up until recently. But now it won't play them anymore AT ALL! The stereo just reads "No Disc". Can you help? Do I need to clean the heads, the laser?
mennyz · August 24, 2005 - 12:06 EST #20
How do I play something that uses Quicktime in our language lab?
ATPM Staff · August 24, 2005 - 13:57 EST #21
Mennyz - you'll have to be more specific. Anything that is QuickTime compatible, you should be able to simply open it in QuickTime Player. If you do not have QuickTime installed on a PC, you can download it.
anonymous · May 21, 2006 - 10:14 EST #22
I have a portable cd/mp3 player. I use a TV which uses PAL. I can watch VCD's on my TV when I switch to PAL using the cd player remote. But, the mp3's play on my TV using NTSC only. There is no option of switch to PAL. Please find me a way out of this problem so that I can see the mp3 disc's playlist on my TV. Is there a way to create PAL mp3 discs?
ATPM Staff · May 21, 2006 - 13:55 EST #23
An MP3 disc is an MP3 disc. There is no NTSC or PAL version. It's a matter of the device being used to show a playlist on your television. If your CD/MP3 only outputs NTSC video, then that's all you're going to get. If your player has a setting to switch to PAL for the VCDs, that's because it recognizes them as a video source and can send either PAL or NTSC format. If that's the case, there should be some setting in your CD/MP3 player to let you change the format for your MP3 discs. Of course, are you certain that your player actually has the function to output a video screen listing of the files on an MP3 disc? I'm taking for granted you know of this feature. Thus, you must determine whether the player can output PAL when using the MP3 listing feature.
Laith qaffaf · June 29, 2006 - 05:16 EST #24
I'm wondering if there's any adapter or enhancement can be added to my car CD player to make it play MP3 songs. I have a BMW businees CD player and i don't wanna ruin the dash board shape by changing the CD player into another kind of MP3 player.
ATPM Staff · June 29, 2006 - 09:48 EST #25
Laith - if you don't have any particular love of the factory CD player, if you shop around a little bit, you'll usually always manage to find an aftermarket head unit that looks good in your particular dash, along with the mounting bracket to fill in unused space.

If your existing unit does not support MP3 discs (have you tried it?) you'll need to contact the manufacturer of the particular device in your car. It's unlikely that if it has any capability of playing MP3 discs that it would come disabled. Putting in an aftermarket CD/stereo is probably the only option.
Kene · August 17, 2006 - 14:18 EST #26
can anyone help me! i cant hear the MP3 audio sound when i play.
ATPM Staff · August 17, 2006 - 14:48 EST #27
Kene - you'll need to be more specific. Our best guess is that you might be trying to play an MP3 CD in your car? If so, are you sure your car stereo supports MP3 CDs? If this isn't your problem, please describe what you're trying to do and exactly what happens (or doesn't happen) and let's see what we can do.
Joseph Phan · October 4, 2006 - 23:29 EST #28
hey, i have a panasonic cd player and for some reason there is not sound coming out when i try to play a cd or use the radio. The sound worked fine for a month and a half after i got the new CD player but not it says the cd is playing and reads what time it is and tells me the track but there is no sound feedback, and when i switch over to the radio there is no sound either. No sound is coming from either of my speakers. Please help
eduardo · October 30, 2006 - 03:01 EST #29
Hi, I've got a stereo in my car (2005 model) which I use to play burnt CD from Itunes. On the options mode of my car's stereo it gives me the option of Compress On/Off, I guess my question is what is that for? And which are the pros and cons of listening to my music on ON as Opposed to OFF...
Lee Bennett (ATPM Staff) · October 30, 2006 - 18:00 EST #30
Eduardo - without knowing the brand and model of the stereo, I can't say for sure, but my guess is that a Compress option on a car radio would be to keep volume levels within an average range, so that nothing was ever too soft or too loud. This has obvious advantages, but the main disadvantage is that you lose dynamic range of music that has soft and loud parts. But when driving in a car, you probably wouldn't perceive the loss anyway.
Max Vanderlubbe · May 13, 2008 - 16:22 EST #31
MP3 can easily be compressed by changing the bitrate.
A bitrate changer can be found by typing "bitrate changer" in to Google.
I use this for embedding MP3 disguised as Wav files in to Powerpoint presentations.
This is needed for emailing.

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