MP3 file sizes

  montyburns 10:32 26 Feb 2004

Just bought a Neo Car Jukebox (which is like an MP3 player for the car, but also is effectively simply a hard drive you can store files on)

Their advertising blurb says you can fit 10,000 songs/800 CDs on it.

I've started copying CDs (at 160Kbps) and have worked out that at this bitrate, I'll "only" get around 260 CDs on. I've read in various places that 128Kbps is acceptable, in others that it's useless. To get the claimed 800 CDs I reckon I'll be on about 50-60Kbps which is bound to sound awful..

So two questions:-

1) What rates do other folks sample at, for iPods etc?
2) Is there anyway to convert the existing 160Kbps files into 128Kbps or lower, or will I be better off just copying from the CDs again (I've only done around 25 so far)

Thanks for any info


  leo49 10:48 26 Feb 2004

I personally don't find 128 acceptable but others do and it's probably pure bigotry on my part - I wouldn't go any lower though.

You can re-encode the ones you've already done with dbpoweramp music converter[freeware].

click here

  temp003 10:57 26 Feb 2004

What's important is how much storage they say the Jukebox has, in GB or MB. The number of songs is usually based on a bitrate of 128kbps, and perhaps 4 minutes per song (so you can see how inaccurate the estimate of no. of songs can be - no. of CDs is even more ridiculous).

At 128 kbps, the music will be about 1MB per minute. 4MB per song. 10,000 songs suggests it has 2.5GB, so would your Jukebox have 2 or 3 GB?

At 160kbps, the file size is about 1.25MB per minute (just a rough pointer).

I think before you start encoding your MP3s, you should take it slowly and try comparing the results with different bitrates, and play them in the jukebox in the car.

128kbps is acceptable to a lot of people, but who are we to tell you that you couldn't tell the difference between 128 and 160kbps or even higher bitrates, if you do detect the difference?

It also depends on the type of music. If you have a lot of instrumental music, a higher bitrate may help.

I always do it at 128 myself, but then I'm not an audiophile, and the equipment I use is not that great anyway.

Whether you can change the existing 160kbps MP3s to 128 bitrate directly may depend on your software. I use CDex and I think one can. For me, I could change the bitrate settings, then select an MP3 file to re-encode it. Some people may say encoding it twice will degrade the quality, but I don't really think so.

But to be safe, re-rip the CDs and do it at 128 if that's what you want. Or leave them be, it's only 25CDs.

BTW, do you really need to squeeze all of 800 or whatever CDs into the Jukebox? If you think 160 sounds better in the car, then use 160 bitrate. I doubt you will have enough time to listen through all 800CDs in the car, before the Jukebox packs up :o)) (It is after all a hard disk which has a limited life.)

  scotty 11:00 26 Feb 2004

I have files using 128kbit and 192kbit and can hear no difference. However, it will depend on your hearing, the equipment you use it on and the environment in which you listen to it. e.g. if you are using it in a car you will get away with a lower quality.

I suggest you take one cd and create MP3 files at different settings and decide what sounds OK to you.

  montyburns 11:16 26 Feb 2004

Yes I forgot to mention HDD size!

The one I wnet for is 40Gb, so you'd think you'd get shedloads on! There's also an 80Gb, a 120Gb and a 160Gb

Price wasn't a real issue, I could have got any without any real probs. But I have about 380 CDs after 20 years of collecting and didn't see the point of anything bigger than the 40Gb with it's claimed 800CD capacity

I would like to have ALL my CDs on the drive! The reason is that if there is enough room, maybe I won't listen to them all (!) but at least if they are there, I'll have the option and also will come across stuff I've not heard for years or even maybe heard at all! I don't want to be bothered constantly deleting and re-recording. Once they are on, I want them to stay on

I must admit that I am disappointed that I may be compromising.....

Thanks for advice above


  Â ÑÌÇKÑÂMË 12:20 26 Feb 2004

I alwats rip mine as cd quality highest bit rate i can usually 192 or above but you do get big files at the end with a frequency of 41.100,can go to 44.000, have about 10 gigs worth on my hdd at the moment and u can tell the difference,but if you gonna rip at a high bit rate i find it best to do it slowly to get a better rip.


  temp003 13:01 26 Feb 2004

Sorry, 4MB per song, 10,000 songs (should have multiplied not divided) means 40,000MB=40GB, which is exactly your hdd size. So the manufacturer hasn't misled you (or rather has adhered to the common standard of 128kbps, 4 minutes per song).

The 800 CDs claim seems to be based on 50 minutes per CD. An audio CD can contain 74 minutes of music maximum, but the figure of 50 minutes per CD is probably closer to the pop world reality.

But I don't think you need to worry about space.

Even at 192kbps (1 minute=1.5MB), 40GB can still hold 26,666 minutes of music. Assuming each audio CD is at full capacity (i.e. 74 minutes), it can hold 360 CD.

Audio CDs are hardly anything near 74 minutes (classical music CDs are usually better), so you must be able to put all your CDs on to the jukebox, probably with room to spare.

I'm assuming you're using the standard sampling rate of 44.1 kHz as well. There's not much point in using a higher sampling rate.

  de_de 15:17 26 Feb 2004

I am not a serious audiofile, but i do like good quality home music system is better than most, and my computer set-up regarding music is important to me. I have found 128kbps to be perfectly acceptable. Theres little difference going any higher (only for serious audiofiles i reckon). I had this same dilemma recently, just glad i stuck with 128 or i'd have needed a new hard disk by now!

  montyburns 16:54 26 Feb 2004

I'm going to try copying at 128Kbps later for an album I already have on at 160Kbps and then listening to see if I can hear any difference!

If it's OK at 128 I'll stick to that I think!

How do I know what sampling rate (44.1Khz mentioned above) I'm using? And how do I change it, what is best to use etc? I'm using iTunes to rip CDs into MP3 and it's giving me file sizes, on average, of around 4500 to 5000 Kb for an average sized song...

Thanks for all the info so far


  temp003 04:20 27 Feb 2004

Sorry, the sampling rate is a red herring. Some programs have an option for output sampling rate (when the output file, not just limited to mp3, gets played). iTunes doesn't have that. Please ignore it. In any event, the output file size is determined by the selected bitrate, which you have chosen as 160 or 128kbps.

The file sizes of 4500 to 5000 KB (or 4.5 to 5 MB) sound right to me, based on a bitrate of 160kbps. They will be back to about 4MB on average per song if you use 128kbps.

You can actually calculate the file sizes based on the bitrate. The "bit" is the computer data. The bitrate simply means how many bits there are in the output digital file, per second of music.

128 kilobits per second=60 x 128 kilobits per minute=7680 kilobits per minute.

1 Byte=8 bits

So 7680 kilobits a minute = 960 KiloByte (KB) per minute = slightly under 1MB per minute.

So at 128 kbps bitrate, a 4-minute song should be just under 4MB.

Silence at the beginning and end of a song will make the file slightly smaller.

At 160kbps, there is 1.25 times as much data in the file as 128kbps. So for a 4 minute song, it should be just under 4MB x 1.25=5MB. So your iTunes is doing right.

As I said, if after comparing the 2 bitrates, you do feel that 160kbps sounds better in the car, keep 160kbps. You don't need to compromise on the quality because 40GB is more than enough to hold your 380CDs (even at full 74 minutes of music per CD) encoded at 160kbps.

40,000MB divided by 1.25MB per minute (at 160kbps) = 32,000 minutes of music

32,000 minutes divided by 74 minutes per CD = 432 CDs.

Your Jukebox is capacious enough to take all your CDs encoded at 160kbps, with room to spare.

  montyburns 17:59 27 Feb 2004

Thanks for this extremely informative answer!!

It certainly would seem that I have plenty of room, at either 160Kbps (preferred) or 128Kbps

I'm just confused at

a) How Neo can claim 800 CDs (10,000 songs)and
b) Why the drive is reporting 4,113,596,416 bytes used for 26 albums, which is 158,215,246 bytes per album or approx 15,821,524 bytes per song! This can't be right, but it's this that made me think that the albums wouldn't fit! I have around 35,892,559,872 bytes left, which at 158,215,246 bytes per album means another 226 albums (thus around 252 tops)

I must admit I AM getting confused but it seems the consensus is carry on at 128 or even 160 and they'll all fit!

Thanks again!


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