Help: Converting AAC to Apple Lostless

[JiPod]

I hope I got the right forum.

My DAP is an iPod Touch 1G. My music is either copied directly from CD to Apple Lostless format or downloaded from iTunes Store (AAC format).

Let's put aside music copied from CDs. I was wondering if I convert my AAC files to a higher bit-rate or convert to Apple Lostless, will this make a difference? I understand that data compression is possible, but is the opposite (data "decompression") possible?

 

[cash68]

No, it is not possible. You have removed the information when you compressed it, you cannot go "backwards" to a lossless source.

 

[Postal_Blue]

Converting from a low bit rate AAC to a higher bit rate AAC would actually stand to lessen the s/q of the file. As the compression would be reapplied to the music. The only way to improve the s/q of a low bit rate music file be it aac, mp3, wma ect.. is to replace it with a higher bit rate file.

 

[soozieq]

Once a file's been compressed to a lossy format, part of the data is discarded and you can't get it back, no matter what you convert it to.

 

[JiPod]

Quote:

Originally Posted by Postal_Blue /img/forum/go_quote.gif Converting from a low bit rate AAC to a higher bit rate AAC would actually stand to lessen the s/q of the file. As the compression would be reapplied to the music. The only way to improve the s/q of a low bit rate music file be it aac, mp3, wma ect.. is to replace it with a higher bit rate file.

Makes perfect sense. Thank you.

 

[krmathis]

AAC is a lossy codec. Meaning that it throw away audio data on encoding.
Transcoding those AAC files to Apple Lossless will result in files 3-6 times as large, with no increase in sound quality. Since it can't recover the data lost during encoding to AAC.

So either live with those AAC files, or re-rip directly to Apple Lossless.

 

[JiPod]

Quote:

Originally Posted by krmathis /img/forum/go_quote.gif AAC is a lossy codec. Meaning that it throw away audio data on encoding. Transcoding those AAC files to Apple Lossless will result in files 3-6 times as large, with no increase in sound quality. Since it can't recover the data lost during encoding to AAC. So either live with those AAC files, or re-rip directly to Apple Lossless.

Noted. Thanks.

 

[apatN]

Nope can't be done.
AAC is lossy so some of the information in the music file is already gone. ALAC is lossless meaning all the information from the CD is in your music files.

 

[JiPod]

Quote:

Originally Posted by apatN /img/forum/go_quote.gif Nope can't be done. AAC is lossless so some of the information in the music file is already gone. ALAC is lossless meaning all the information from the CD is in your music files.

Thanks.

 

[apatN]

Woops. I screwed up. AAC IS OF COURSE NOT LOSSLESS but lossy. My bad. I'll edit my post.

 

[intoflatlines]

What everyone else said.

I find the 128 Kbps AAC files downloaded from the iTunes store sound bad, but I personally rip most of my casual listening CDs as 192 Kbps AAC and it sounds pretty good. So, if you have the iTunes Plus files you might not notice a huge loss in sound quality (IMO). If you've got the standard 128 Kbps, too bad.

 

[cash68]

I THINK PEOPLE CAN QUIT POSTING. His question has been answered like seven times.