Some nagging iTunes & iPod questions
in [Mac Systems]
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From: Wes Groleau on 2 Aug 2010 17:49 On 08-02-2010 13:37, MartinC wrote: > There used to be even more, but it will be hard to find any more decoders if > you happen to locate a file... ..wma ? (Mention does not imply endorsement!) -- Wes Groleau Promote multi-use trails in northeast Indiana! http://www.NorthwestAllenTrails.org/
From: MartinC on 2 Aug 2010 18:01 Wes Groleau wrote: > An answer was that "it is a bit-copy" which I questioned. > > Subsequent clarifications established that Apple lossless > is _not_ a bit-copy. > > Which does not prevent it from being "virtually indistinguishable > from CD quality source material" to the ear, and if I implied > otherwise, please forgive. You confuse "compression" with "loss". It has been explained (here) in detail. Do you know what a ZIP archive is? If you compress something into a ZIP archive then it gets smaller. If you expand it afterwards, you get your file back. As a bit-copy! The ZIP file is not a bit-copy, but the content, once you expand it back. It is not "virtually indistinguishable" from the source file, it *is* the source file. Apple Lossless is "ZIP for audio". The ALE file is not a bit-copy, but the content, once you expand it back. And a final hint: The fact that the ALE file is smaller than the source file, is actually a feature. That's why you *do* it. Google "ZIP" for further details.
From: Wes Groleau on 2 Aug 2010 18:59 On 08-02-2010 18:01, MartinC wrote: > You confuse "compression" with "loss". No I don't. He mentioned Apple lossless. You said it was a bit-copy, and I questioned that. I think , however, that all the semantic arguments, have cleared up what we all meant (except for that large Usenet subculture whose purpose in life is to argue) I am fully aware of the difference between loss of quality and loss of size. But not being an audiophile, I am less aware of more subtle differences in algorithms. -- Wes Groleau Angry disruption in class http://Ideas.Lang-Learn.us/barrett?itemid=1455
From: Ian Gregory on 2 Aug 2010 19:24 On 2010-08-02, Wes Groleau <Groleau+news(a)FreeShell.org> wrote: > Subsequent clarifications established that Apple lossless > is _not_ a bit-copy. Of course the *compressed* file is not a bit-copy (if it was it wouldn't be compressed), but you can't listen to a compressed file without first decompressing it, and the decompressed file (for any lossless codec such as Apple Lossless) *is* a bit-copy of the original file and must therefore sound *exactly* the same. That is the definition of lossless. If you compress and then decompress using a lossy codec then the resulting file is not a bit-copy of the original file but hopefully it sounds almost the same. Ian -- Ian Gregory http://www.zenatode.org.uk/
From: Ian Gregory on 2 Aug 2010 19:42
On 2010-08-02, Wes Groleau <Groleau+news(a)FreeShell.org> wrote: > Then, again, neither is a "bit-copy" as you suggested earlier. > Which is why I asked "is it really?" But it doesn't make any sense to talk about codecs in which the encoding algorithm produces a bit-copy of the original file. There is only one that does and that is the trivial Identity codec, ie the one which does nothing at all. With codecs you never listen to the encoded file (it would just be white noise) - you have to run the corresponding decoding algorithm first. The file you get back after decoding may or may not be a bit-copy of the original file. For any lossless codec such as Apple Lossless the resulting file *is* a bit-copy of the original and for lossy ones it is not. Ian -- Ian Gregory http://www.zenatode.org.uk/ |