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Re-record iTunes protected AAC music to MP3
Authored by: Jwink3101 on Feb 08, '06 09:14:40AM

really? I was under the impression that with any of the sound recording programs that record what is going out like Audio Hijack and WireTap are 1:1 of the music. I thought you lose quality with the CD because you are converting it and re-encoding it many times.



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Authored by: jiclark on Feb 08, '06 11:23:50AM

As this question seems to be the crux of the entire issue: how to make an unprotected copy of the file that has no loss of audio quality. Burning to CD, then reimporting *definitely* results in loss of quality (whether or not it's noticeable, and aside from the issue of losing all metadata).

I would assume that AHP could make a recording of iTunes' output in such a way as to avoid any further compression, and hence, no loss of quality. I don't know if this is right or not though. Does anyone here know for sure?

Thanks,
John-o



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Authored by: brainzelda on Feb 08, '06 12:20:56PM

You would lose quality in both the cd burning case and in the ahp case. When the music is burned to CD the aac is converted to wav in the decoding process in order to be burned. The reimport is obviously then of lower quality of the original. In the AHP case, the aac is still being decoded when played through the computer, even though it's not being burned. So the aac>wav>mp3 will still result in quality loss. I don't think there is any way to avoid this in any case.



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Authored by: kirkmc on Feb 08, '06 12:23:45PM

Why is it of lower quality? If you burn a CD, then import in the same format and bit rate, the quality should be the same. The algorithm for compressing the music doesn't change...

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Read my blog: Kirkville -- http://www.mcelhearn.com
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Authored by: brainzelda on Feb 08, '06 12:30:22PM

That's exactly the point. When the aac was first ripped at wherever Apple rips its music, it used an algorithm(codec) to compress the cd to aac. That in itself result in quality loss because the algorithm inherently removes data from the original wave. That's why an aac is much smaller than the original wave. When you burn that aac to a cd and rip it again, it loses even MORE data since youre using a similar algorithm again. The original data lost is not recoverable. Everytime you rerip you're losing more and more data. That's why people try to stay away from reencodes of files already encoded in the first place.



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Authored by: el bid on Feb 10, '06 01:44:57AM

This is strictly accurate, but the argument against recompression is easily overstated.

Audio compression systems combine lossless compression with psychoacoustic compression. For present purposes we can ignore the lossless element. The psychoacoustic compression is carried out differently with different compression systems, but is essentially based on the same set of rules derived from our understanding of how the human ear hears. Eg, ignore all data above such and such a frequency. Eliminate data for particular frequencies occurring at the same time as other particular frequencies, because they'll be masked anyway. And so on.

AAC -> WAV/AIFF incurs no loss -- we're simply expanding the compressed data

WAV/AIFF -> MP3 will technically lose data, but (providing the squash isn't too tight) will mostly be throwing away data that isn't there anyway, because it's operating by much the same filter/masking rules as the original AAC compression.



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el bid



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Authored by: jpmack on Feb 09, '06 04:16:18PM
As this question seems to be the crux of the entire issue: how to make an unprotected copy of the file that has no loss of audio quality.

JHymn will do this.

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JHymn does *not* work with iTunes 6.x!
Authored by: jiclark on Feb 09, '06 05:28:42PM

They're working on it, but saying it will take some time!!



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