[ascl]

Quote:

Originally Posted by imdskydiver /img/forum/go_quote.gif ALAC is compressed so something is removed and if it is not music then it is something else , like sounds out side the range of your hearing .

No, this is not correct at all. Think of it like this:

uncompressed data: aaaaaabbbbb
compressed data: 6a5b

Nothing is lost using this very simple compression scheme, but the overall size of the data is smaller.

 

[ascl]

The edit button crashes my browser!

Anyway, something is definitely removed but its not lost.

Lossy compression formats do usually use some kind of low pass filter to chop out bits that outside of the average hearing range.

 

[UNHchabo]

Quote:

Originally Posted by imdskydiver /img/forum/go_quote.gif ALAC is compressed so something is removed and if it is not music then it is something else , like sounds out side the range of your hearing .

MP3, AAC, Ogg Vorbis, and other lossy compression formats throw out data they deem to be less important in order to achieve the filesizes desired by the user. Depending on the bitrate or quality metric specified, and on the source material, this can result in only a little bit of data being discarded, or quite a lot.

ALAC, FLAC, and the other lossless compression formats don't throw out any data; they merely encode it in a way that space is saved without throwing out any data.



ascl's analogy with 'a's and 'b's is apt, but here's something more concrete:
If you have a CD filled with nothing but 60 minutes of digital silence, and rip that to a .wav file, you'll have a 620MB file containing little except a bunch of zeroes.
Compress that file using FLAC or ALAC, and you'll have a very small file (in the KB range, most likely), because all those zeroes can be compressed very easily.

Take a different 60 minute CD, containing complex music. Rip it to an .aiff file, and you'll have a 620MB file containing your music data. Compress it to 320kbps CBR MP3, and you'll have a 140MB file, containing less information than you had in your CD, because your MP3 encoder decided that some of that information could be thrown away for the sake of saving space. If you decode the MP3 file back to an .aiff file, it will be different than the original, even though it will be the same size (620MB).
Now take the .aiff file you originally ripped from the CD earlier, and encode it to ALAC. The encoder will do the best job it possibly can to compress the file, but the top priority is that no information be thrown out. Because of this, your 620MB file may only be compressed down to 550MB, if the music is very complex.

Now take that 550MB ALAC file, and decompress it back to an .aiff file. It will be 620MB, and more importantly, it will contain exactly the same audio data as the original. You can verify this with various tools available online.

 

[krmathis]

Quote:

Originally Posted by imdskydiver /img/forum/go_quote.gif ALAC is compressed so something is removed and if it is not music then it is something else , like sounds out side the range of your hearing .

What are you talking about?

Have you even looked up on lossless data compression before making such a faulty statement? Clearly does not look like you have!

No data is removed. It is simply compressed using specialized mathematic algorithms, just like Zip files you might be familiar with.

Quote:

Originally Posted by ascl /img/forum/go_quote.gif Anyway, something is definitely removed but its not lost. Lossy compression formats do usually use some kind of low pass filter to chop out bits that outside of the average hearing range.

Yes, for lossy compression that is true.
But that is irrelevant to this thread since ALAC is lossless, not lossy.

 

[peanuthead]

Quote:

Originally Posted by imdskydiver /img/forum/go_quote.gif ALAC is compressed so something is removed and if it is not music then it is something else , like sounds out side the range of your hearing .

Facepalm

 

[CTechKid]

iTunes' error correction is mediocre. If you can guarantee that the source CD is 100% scratch/blemish free than itunes is a satisfactory ripper. For anything below 100% on the condition scale I would use XLD. Just my opinion.

 

[Ra97oR]

Quote:

Originally Posted by CTechKid /img/forum/go_quote.gif iTunes' error correction is mediocre. If you can guarantee that the source CD is 100% scratch/blemish free than itunes is a satisfactory ripper. For anything below 100% on the condition scale I would use XLD. Just my opinion.

Totally agree as a main iTunes user.

I use EAC to rip any CD that is not brand new.

 

[aimlink]

Ripping with iTunes to ALAC pretty much exclusively. I recently started using XLD which does the job good too. With error correction on I really don't see the fuss between encoders.

 

[Ham Sandwich]

Quote:

Originally Posted by krmathis /img/forum/go_quote.gif Sadly not! Reading metadata yes, but not writing.

That's a big potential gottcha for anyone considering those tools. Any tagging changes you make to the FLAC files will be trapped in the iTunes database and won't/can't get written back to the FLAC files.

I'd not be a happy camper if I made a lot of tagging updates and then discovered that I couldn't export or use those tagging changes outside of iTunes. It would be like a Roach Motel (Tags check in, but they don't check out!).

I can see those tools being useful (very useful). But one would have to know the gottchas.

 

[eyeshigher]

 

[SDDL-UP]

I ripped my CD collection to FLAC, but any lossless format will do. If you are unhappy with FLAC or ALAC you can convert to another lossless or back to the original .WAV file at any time.

6a5b is stored smaller than aaaaaabbbbb - as far as I know lossless compressions give about a 50% file size reduction. They are translated out when they are played from 6a5b to aaaaaabbbbb just like the original .WAV so you should never hear a difference. If you are hearing a difference perhaps there is something wrong with the system, like it's taking too long to uncode the lossless format. Given the computing power today I doubt that's the case. I'm not sure why else you would have a problem.

 

[ejy99]

[size=10pt]Well, I'm new to the forum.  First post and all.  [/size]
 
[size=10pt]I have read all of your input extensively and I should make it known that I am no audiophile, I just love music, have a ton of it, only own Mac's, use iPods, have an iPhone, and use iTunes for everything.  [/size]
 
[size=10pt]I too want to rip my entire music collection (600+) cd's into iTunes.  My intent before reading this entire posting was to rip an uncompressed file format (AIFF) in iTunes of all my cd's for archival purposes.  I was then going to get rid of the many boxes of cd's my collection occupies and only have digital copies of everything.  I would archive all the files on external hard drives and play them as needed through iTunes, of course keeping a stored HDD for backup.  If I needed to compress any cd's or songs into MP3, or AAC for use on one of my many apple devices, I could do that using the uncompressed (AIFF) files as many times as I desired getting the same result every time.  I understand that if I were to use a lossy format (AAC) and then try to compress the AAC to MP3 for whatever reason, I would just be compressing compressed data and would get crap as a result.[/size]
 
[size=10pt]Now, after reading all of your comments, I am unsure of a few things I'll list below for you all to help me determine if you don’t mind...[/size]
 
[size=10pt]1.  Can I re-encode from uncompressed (AIFF) to a lossy format as many times given the same result every time?[/size]
 
[size=10pt]2.  If I use iTunes to pull CD track info and I manipulate the file metadata in iTunes, will the conversions I do in question 1 cause me to lose any cd track info (downloaded from the net or manually input)?[/size]
 
[size=10pt]3.  Am I making a mistake using AIFF, and should I just use Apple Lossless (ALAC) for the original uncompressed archive copies?  I get how the algorithms just change the data, without getting rid of anything, but I'm still hesitant since I want the best original archived copy for future compressing and burning to CD again[/size]
 
[size=10pt]4.  Would burning (AIFF) files to a CD give you the exact same sound quality as the original CD?  How about burning (ALAC) to CD?[/size]
 
[size=10pt]5.  If I do need to make a conversion from Uncompressed (AIFF) or lossless (ALAC) to lossy (MP3/AAC) for use on my iPhone/iPods in my car or just using headphones, what is the best kbps to use to get as close to CD quality as I can without sacrificing space?[/size]
 
[size=10pt]6.  Do I really have to worry about the conversion quality using iTunes like some have said.  Most of my CD's are in good shape.  Whats the best alternative for lightly scrached CD's?[/size]
 
[size=10pt]I'm sure I have more questions, but these are the majority of them.  You all seem very knowledgeable, so I am sure someone can help me out.  I know there are a lot of questions here but I need some direction.  Thanks in advance for the help!  [/size]

 

[Todd R]

Quote:

[size=10pt]Well, I'm new to the forum.  First post and all.  [/size]
 
[size=10pt]I have read all of your input extensively and I should make it known that I am no audiophile, I just love music, have a ton of it, only own Mac's, use iPods, have an iPhone, and use iTunes for everything.  [/size]
 
[size=10pt]I too want to rip my entire music collection (600+) cd's into iTunes.  My intent before reading this entire posting was to rip an uncompressed file format (AIFF) in iTunes of all my cd's for archival purposes.  I was then going to get rid of the many boxes of cd's my collection occupies and only have digital copies of everything.  I would archive all the files on external hard drives and play them as needed through iTunes, of course keeping a stored HDD for backup.  If I needed to compress any cd's or songs into MP3, or AAC for use on one of my many apple devices, I could do that using the uncompressed (AIFF) files as many times as I desired getting the same result every time.  I understand that if I were to use a lossy format (AAC) and then try to compress the AAC to MP3 for whatever reason, I would just be compressing compressed data and would get crap as a result.[/size]
 
[size=10pt]Now, after reading all of your comments, I am unsure of a few things I'll list below for you all to help me determine if you don’t mind...[/size]
 
[size=10pt]1.  Can I re-encode from uncompressed (AIFF) to a lossy format as many times given the same result every time?[/size]
 
[size=10pt]2.  If I use iTunes to pull CD track info and I manipulate the file metadata in iTunes, will the conversions I do in question 1 cause me to lose any cd track info (downloaded from the net or manually input)?[/size]
 
[size=10pt]3.  Am I making a mistake using AIFF, and should I just use Apple Lossless (ALAC) for the original uncompressed archive copies?  I get how the algorithms just change the data, without getting rid of anything, but I'm still hesitant since I want the best original archived copy for future compressing and burning to CD again[/size]
 
[size=10pt]4.  Would burning (AIFF) files to a CD give you the exact same sound quality as the original CD?  How about burning (ALAC) to CD?[/size]
 
[size=10pt]5.  If I do need to make a conversion from Uncompressed (AIFF) or lossless (ALAC) to lossy (MP3/AAC) for use on my iPhone/iPods in my car or just using headphones, what is the best kbps to use to get as close to CD quality as I can without sacrificing space?[/size]
 
[size=10pt]6.  Do I really have to worry about the conversion quality using iTunes like some have said.  Most of my CD's are in good shape.  Whats the best alternative for lightly scrached CD's?[/size]
 
[size=10pt]I'm sure I have more questions, but these are the majority of them.  You all seem very knowledgeable, so I am sure someone can help me out.  I know there are a lot of questions here but I need some direction.  Thanks in advance for the help!  [/size]

Don't know if you realize it or not, but the latest versions of iTunes have the option to automatically convert songs to 128kbps AAC when you drag them on to your iPod, iTouch, iPhone, etc. (Plug in your device and click on the summary tab)
That will leave your original files alone and will also keep you from creating a second set of compressed music for your portable device.

 

[ejy99]

[size=10pt]I hadn’t noticed that, but that will be very useful.  Thanks a lot Todd R[/size]

 

[ejy99]

[size=10pt]I hadn’t noticed that, but that will be very useful.  Thanks a lot Todd R[/size]