AIFF/WAV file size problem

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pdx_pdx
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AIFF/WAV file size problem

Post by pdx_pdx » Tue Jul 15, 2008 10:08 am

Hello Folks,

Thanks in advance for your time in helping me with this question.

I am in the midst of making a mix cd for a group of friends. I have put together the perfect playlist in iTunes but it's just a little to big to fit on the disc. My first thought was to resample some of the music in order to make the files smaller but this doesn't seem to be working. My source files are all 320kbps mp3s that I am then converting to AIFFs (44.100khz, 16bit, stereo) for burning. My thought was to resample the mp3s to be slightly smaller (224kbps, for instance) which would then lead to the final AIFFs being smaller as a result. This seems logical but its not working. Regardless of the bitrate of the source mp3, the resulting AIFF is always the same size. Am I missing something here? I have scoured the internet for this simple question and I have come up empty.

And yes, I realize that the workflow I am talking about here will not result in the finest audio quality but I am OK with that.

Thanks again!

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Post by JGriffin » Tue Jul 15, 2008 10:16 am

An mp3 file is a compressed format file that can be different sizes. An .aif file --when used for an audio CD*-- is not and can't. It's 16 bits, 44,100 kHz. That defines its size. It does not change. (rule of thumb: 5 MB/min in mono, 10 MB/min in stereo --though it's a little less than that really in practice, as you'll see. It makes the math clean though)

A standard audio CD holds between 74 and 80 minutes of music depending on what kind of blank CD you're dealing with, and that's your limit.

So: it doesn't matter what size mp3 you're starting with, once you convert to .aif the size is set.

Your other option is to make an mp3 CD, but you need special players/computers for that, it won't work in a standard audio CD player.




* there ARE different sizes of .aif files, but not for use on an audio CD. Other sample/bit rates etc. exist but if you put them on an audio CD it won't play right.
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Jay Reynolds
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Post by Jay Reynolds » Tue Jul 15, 2008 10:19 am

Are you asking itunes to apply crossfades to the cd? If you are and that is still not helping, I'd say that you're "over the line". This isn't Vietnam, Smokey. There are rules.
Maybe see if you can use your audio editor to crop some of the dead space from the beginnings and endings of the tracks. Or you might see if there are some fade-outs that can happen faster. Or just cut out some sections. Or get rid of the last song on the mix.
Prog out with your cog out.

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nerdtronica
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Post by nerdtronica » Tue Jul 15, 2008 10:21 am

Yeah, it's about the length (minutes and seconds) of the track and not about file size (mB).

Unless, you make a data mp3 disc as suggested, but only certain players will work.

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Post by pdx_pdx » Tue Jul 15, 2008 10:39 am

Thanks a lot for all the quick, good feedback. I had a feeling that there was nothing I could do outside of chopping seconds off of songs or dropping whole songs off entirely. Luckily for me, since I typed this question, I realized that the media I was using was mislabeled -- I thought it was 80min when it's actually 74min. I have since tried an 80min CDR and it burns fine which I kind of don't understand because while the mix is 78mins long, it also says that it's 790mb. How is it fitting on a 700mb,80min disc?

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nerdtronica
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Post by nerdtronica » Tue Jul 15, 2008 10:46 am

pdx_pdx wrote:Thanks a lot for all the quick, good feedback. I had a feeling that there was nothing I could do outside of chopping seconds off of songs or dropping whole songs off entirely. Luckily for me, since I typed this question, I realized that the media I was using was mislabeled -- I thought it was 80min when it's actually 74min. I have since tried an 80min CDR and it burns fine which I kind of don't understand because while the mix is 78mins long, it also says that it's 790mb. How is it fitting on a 700mb,80min disc?
The data may weigh 790mB when you start, but your CD burning program has rendered your files to a different CD format and all your songs should now have a different size than the original data file (wav or Aiff). Audio CD's are time sensitive, not file size sensitive.

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Post by pdx_pdx » Tue Jul 15, 2008 10:52 am

hmm, what's weird then is that when I do a "get info" on the burned CD, it says it is 790.3mbs in size. It does say "CD Audio" under format rather than "AIFF". I guess I shouldn't question it too much and just be happy that it fits?

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Post by aitikin » Tue Jul 15, 2008 9:20 pm

AIFF/WAV have error correction data in them, which accounts for the extra 100 megs or so. This is why burning a AIFF as a data disc doesn't really work.
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Post by pdx_pdx » Wed Jul 16, 2008 7:38 am

Interesting. Thanks for the informative responses...

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Post by @?,*???&? » Wed Jul 16, 2008 8:10 am

Your burner- depending on 'Write strategy' employed, may allow you to over-write the disc. You'll need to have long format blank CDs to do so.

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Post by ashcat_lt » Wed Jul 16, 2008 11:05 am

2 bytes/sample x 88,200 samples/second x 60 sec/min x 80 min / 1,048,576 bytes/Mbyte = 807.50 Mbytes

Of the above answers, the only one I find acceptable is the one re: over-writing, but I'm still a little confused by the whole thing.

My original idea was that it was a difference in the way megabytes are counted, but that usually works in reverse. My brand new "320Gig" Maxstor HD showed up in Windows as something like 290G, which freaked me out until I dug a little deeper and found that it does, in fact, have capacity to store something close to 320 billion bytes of data. Windows counts the Gigs correctly though: 1024 bytes/Kb x 1024K/M x 1024M/G = 1,073,741,824 bytes/G. This yeilds 298 G out of 320 billion bytes. Maxstor - and, I'd assume, most other HD manufacturers - counts its Gigs decimally, probably to make them look bigger.

I still want to know how you get 790M onto a 700M disk!

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Post by jv » Wed Jul 16, 2008 11:31 am

I think the deal is that those 80 minute disks will hold 80 minutes of music and 700 MegaBytes of data. The reason is that data disks contain extra information for error detection/correction. Audio CDs have some error detection/correction, but not as much as data CDs.

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Post by aitikin » Wed Jul 16, 2008 11:41 am

ashcat_lt wrote:My original idea was that it was a difference in the way megabytes are counted, but that usually works in reverse. My brand new "320Gig" Maxstor HD showed up in Windows as something like 290G, which freaked me out until I dug a little deeper and found that it does, in fact, have capacity to store something close to 320 billion bytes of data. Windows counts the Gigs correctly though: 1024 bytes/Kb x 1024K/M x 1024M/G = 1,073,741,824 bytes/G. This yeilds 298 G out of 320 billion bytes. Maxstor - and, I'd assume, most other HD manufacturers - counts its Gigs decimally, probably to make them look bigger.
That's a marketing thing. You see, back in the day, marketing departments were too stupid to know that 1 kilobyte was not equal to 1000 bytes. Unfortunately that's held over these days. At least they don't work off of bits...
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