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Play Counts and Conversions
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jlehrfeld
Member
 
Join Date: May 2005
 
2006-05-01, 12:13

Okay, I have a feeling I already know the answer to this one, but I'm being pretty optimistic now and holding out...

I want to convert my library of MP3s to AACs to free up more space on my hard drive (I'm a nut when it comes to saving space), but I absolutely refuse to do it if it means I'll lose my play counts in iTunes. Is there any way under the sun that I can avoid losing play counts when converting from an MP3 to an AAC? I work hard to get play counts up there and I do not want to start from the beginning again! (Not to mention some of my most used smart playlists rely on play counts.)

Thanks for any ideas... if there are any... *tries to be hopeful*
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Dorian Gray
Veteran Member
 
Join Date: May 2005
Location: Paris, France
 
2006-05-01, 12:33

In Windows this is a difficult (impossible?) task to perform, but if you're on the Mac there is a straightforward solution: Copy Tag Info Tracks to Tracks. The procedure must be followed with great care, but Doug Adams (the author of the script) includes comprehensive instructions so it shouldn't be a problem.

What would be a problem is converting MP3 to AAC. Both MP3 and AAC are "lossy" compression formats: that is, they achieve high compression ratios by discarding some of the original song information. Think of an MP3 track as a photocopy: it is an acceptable reproduction of the original, but if you then make another MP3 or AAC from that MP3, it is akin to using a photocopy as a source for another photocopy. Sound quality may no longer be acceptable (to me it certainly wouldn't be).

Let's say you have an MP3 track encoded at a bitrate of 192 kbps. If you convert to 128 kbps AAC you will indeed save some space, but you will lose a lot of fidelity. Even if you convert the 192 kbps MP3 to 320 kbps AAC you will lose quality, despite increasing the file size (think of making a very high quality photocopy of the first photocopy: the quality will still be inferior to the first photocopy).

So although it's possible to convert from MP3 to AAC, it's a very bad idea in almost all circumstances. The solution if you wish to use AAC is to rip your music from the CD sources from scratch. Copy Tag Info Tracks to Tracks is very useful for this task too, but it's still a huge task to re-rip all your music.
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jlehrfeld
Member
 
Join Date: May 2005
 
2006-05-01, 12:37

Hmm... well all my MP3s are 128kbps, so would I still be losing noticeable quality if I convert to AAC in that case? (Would I even be saving file space?) Thanks for the script, though, it's GREAT to know that exists!
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Blue Light Bandit
Member
 
Join Date: May 2004
 
2006-05-01, 13:06

1. 128 kpbs is 128 kilobits of data per second of audio. If you convert a 128 kbps MP3 to a 128 kbps AAC, you'll have a file that's the same size.

2. As Dorian Gray said, MP3 and AAC are both "lossy" formats. They throw away bits of the audio every single time you re-encode. This audible distortion gets stronger with lower bit rates. 128 kbps is pretty low.
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jlehrfeld
Member
 
Join Date: May 2005
 
2006-05-01, 13:13

Thanks for all the info guys! I guess I'm going to forego conversion at this point.
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Dorian Gray
Veteran Member
 
Join Date: May 2005
Location: Paris, France
 
2006-05-01, 13:26

Quote:
Originally Posted by jlehrfeld
…my MP3s are 128kbps, so would I still be losing noticeable quality if I convert to AAC in that case?
Yes, you'll lose quality in all cases where you are converting a lossy format (MP3, AAC, WMA, etc.) to another lossy format (including the same format as the original). There is no way around this. The only way to not lose quality is to convert the lossy file to a 5x larger lossless file (an identical copy of the audio information in the lossy file), such as Apple Lossless or FLAC, or to a 10x larger PCM file (AIFF, WAV, etc.). In your specific case of 128 kbps MP3s, you are already at the bare minimum for acceptable music quality, so you have absolutely no margins to drop quality further. In addition, even if you were making AAC files from the original music source (CD, vinyl, etc.), I would strongly advise against compressing to anything smaller than 128 kbps.

And of course if you were converting 128 kbps MP3 to 128 kbps AAC your files would remain exactly the same size, so you wouldn't save disk space either. Reducing the bitrate to 96 kbps would save 25% disk space but the quality would approach that of hold music on a telephone.

For what it's worth, I would be unhappy with 128 kbps MP3 as it is, never mind further reduced quality copies, and in your shoes would make the effort to re-rip my entire collection from scratch. I would choose AAC VBR (Variable Bit Rate) at a nominal bitrate of 192 kbps, and use Copy Tag Info Tracks to Tracks to preserve tag information (play count, etc.). Of course this would actually take up significantly more space than your MP3s (192+ versus 128 kilobits per second), but the sound quality would be much better on good speakers/headphones (though probably not much better with the standard iPod headphones, which are really terribly poor quality).

128 kbps is the absolute minimum for acceptable music quality with MP3. If you're running out of space you have only two options: buy a bigger hard disk or reduce the size of your music collection. Current technology simply cannot offer high quality music reproduction at anything below 128 kbps. Maybe in ten years a new compression format will reduce the size further, though that is doubtful too, because the need for high compression is falling all the time, as hard disk space gets cheaper and internet connections faster.

If you do end up re-ripping all your music, spend at least a couple of weeks familiarising yourself with all the available options before you make the effectively irreversible decision to use a particular codec. Lossless audio codecs you should consider include FLAC, Apple Lossless (ALAC), Monkey's Audio (APE) and Shorten (SHN), while lossy options to research are AAC, LAME MP3, Ogg Vorbis, and Musepack (MPC).

If all this sounds like Greek, don't worry: it's pretty straightforward once you get a conceptual grasp of audio compression. To sum up, if you're happy with the sound quality of your current 128 kbps MP3s, you have nothing to gain from messing with any of these codecs, as your files are already as small as possible. If you want higher quality sound you will probably have to actually increase your file sizes while re-ripping from scratch.
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jlehrfeld
Member
 
Join Date: May 2005
 
2006-05-01, 14:18

Alright, thanks for all the help!
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