Q: Editing audio files with iTunes
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Sep 3, 2016 1:37 AMby Niku,Well, I'm already getting in over my head, but I'll try to explain my thoughts as best I can. There are two reasons why I think/thought that the recording on the CD is 250 MB. First, I had assumed that the person who transcribed the file from the vinyl record to a CD had used the same format and the same compression. That assumption may have been wrong, but I know that an uncompressed sound file occupies about 10MB for every minute, and since the recording is 25-minutes, that would be 250MB (10X25). Next, here is something that I found when I downloaded the CD:
Now I just don't know what to think. Is the sound file in my iTunes library 250MB or not? No, it's not. I just clicked on the listing in my library and got the following reading:
I'll have to quit here for now.. This is getting too long and taking up too much space.
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Sep 3, 2016 1:52 AMby Roger Wilmut1,Let's try to clarify this.
1. CD's contain the audio in a very specific format of uncompressed audio (Solomon-Reed Cross Interleave which includes powerful error correction to allow for scratches etc.) but when you insert a CD into your Mac the Finder shows these files as AIFF and converts them on the fly when you drag them to the Mac. So you can regard the files on a CD as being AIFF (which is uncompressed but with no error correction) even though they aren't.
2. When you drag these or any other compatible audio files into iTunes it copies them into its Library in the format you have set in the Preferences. Currently you evidently have this set to M4A (AAC) which is probably the default.
3. To change this setting go to iTunes Preferences>General. Click the 'Import Settings' button near the bottom right. The 'Import Using' menu enables you to choose the encoder: AIFF, WAV (both uncompressed), Apple Lossless (compressed but without losing data), MP3 or AAC (both compressed). The 'Setting' menu enables you to choose the quality of the compressed encoders, either with the presets they offer or you can set the exact details yourself. Click 'OK' then 'OK again to save the settings.
4. Now when you import CD tracks they will be copied into iTunes in the format and settings you have chosen.
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Sep 3, 2016 2:18 AMby Roger Wilmut1,Section 1 of my post above refers of course to audio CDs - since you didn't specify, I assumed this is the case; of course if it's a data CD the file will be in the format which was burned to the disk in the first place. However the behaviour of iTunes is exactly the same in either case - it will convert any imported audio file that it can read (i.e. not Flash etc) into the format chosen in the settings as described in sections 2-4.
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Sep 3, 2016 3:09 AMby Niku,I set the iTunes download format as AAC because that's the format that the man who made the CD said that the CD uses. At the time, I hadn't realized that it is probably not possible to download uncompressed sound files into iTunes. Why did I want an uncompressed sound file in my iTunes library? Well, I was looking forward to eliminating unwelcome noises from my recording, and the people at Audacity kept telling me that it is best to work with uncompressed files. You might say that this is extremely important to them. Now I think that I can probably work with the file that I have. However, my guess is that I can probably create uncompressed files with GarageBand, or QuickTime, or Audacity, or many other programs if I need to. I just can't do it with iTunes. Oh, I just reread your third paragraph. I hadn't realized that AIFF and WAV would allow me to import uncompressed files into iTunes. Tomorrow (it's now 2:58 AM here), I'll make an uncompressed sound file using either AIFF or WAV, which I will use to "clean" my file of unwanted clicks and pops. I might add that the people at Audacity seem to be purists to me. I don't obsess about creating perfect recordings. I'm happy with recordings that sound good enough, and I don't believe that I have even one uncompressed sound file among my many recordings. As an example, I once compressed a 90-minute recording of the musical "Showboat" into 3.5MB. It still sounds fine to me. Good enough, not perfect.
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Sep 3, 2016 3:45 AMby Roger Wilmut1,When you load the CD into your Mac it will tell you whether it's an audio CD.
If he made an AAC audio file then burnt an audio CD from that you have an uncompressed file but which is of course missing the bits of the audio which were removed when the AAC file was created - you can never restore those, so there would be no point in importing into iTunes as AIFF. However if you want to process the file in Audacity or similar then whatever the format Audacity will open it as an uncompressed file to work on, then save it in whatever format you choose. In your case it's best to import the AIFF file from the CD into Audacity, work on it, then save it as AIFF, then import that into iTunes as AAC if you want to do that. That will reduce the number of times the file gets converted.
If a file was in a compressed format such as AAC in the first place then there's no point in saving it finally as uncompressed. You get people thinking that by doing this they are restoring uncompressed quality but of course you can't do that. AAC files at a reasonably high bitrate are difficult to distinguish from an uncompressed original under most ordinary circumstances.
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Sep 3, 2016 3:51 AMby dialabrain,FWIW, the iTunes import settings only apply to physical audio CDs you import. They have no effect on downloaded files you add to the iTunes Library. Just to add, once an audio file is compressed there is no way to "decompress" it. Whatever losses there are have already occurred. Also, AAC files are compressed with a slightly better result than MP3s. AIFF files are uncompressed.
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Sep 3, 2016 3:56 AMby Roger Wilmut1,That's correct of course, so if you have worked on a file in Audacity you can either save it there as AAC (I assume Audacity does that) or save it as AIFF and import it into iTunes where it will remain as an AIFF. You can then convert it within iTunes by selecting it and choosing 'Convert' from the file menu, then 'Create XXX file' where XXX is the format you have set in the Import Settings. This will create a copy and you can delete the AIFF one.
