Re: Apple Computer changes its name

[pausch@saaf.se (Paul Schlyter)]

In article <1168868350.414093.269480@a75g2000cwd.googlegroups.com>,
 <bieling@terra.es> wrote:

> David Empson ha escrito:
> 
>> <bieling@terra.es> wrote:> You can export iTunes Store protected music as an audio CD (no quality
>> loss from the DRM protected AAC file) but then to get into an
>> unprotected AAC or MP3 you would have to compress it again, which is a
>> second compression of the original full quality music (which you didn't
>> have in the first place).
>> David Empson
>> dempson@actrix.gen.nz
> 
> Let's say that we've got a music file with a bitrate x. We burn this
> file into a CD (AIFF), then we encode it from the CD's AIFF into
> another mp3 file with the same bitrate x as the original. The question
> is, have we really lost any quality in the process? I ask because I'm
> not so sure... ?
> 
> Regards,
> Jorge.

First, the bitrate isn't all that matters.  The sample rate matters too.
If the original has a sample rate exceeding 44100 Hz, then burning it onto
a CD will have to lower the sample rate, which means a drop in quality.
You might not hear the difference (in particular if you're old), but your
dog and/or your bat definitely will... :-)

Second, lossy compression schemes (most audio compression is lossy)
will throw away some of the data to gain a smaller file size - the
idea is to throw away such data that is inaudible.  However, different
algorithms may have different ideas about what's "inaudible".  And if
you apply two lossy compression schemes after one another, too much may
be thrown away so that even a middle-aged human will hear a difference.

Does this matter?  It depends -- if you really like the song, maybe
you'd want to buy it on CD anyway.  And if you don't like it enough to
buy it on CD, maybe the (hopefully small) loss of audio quality won't
matter that much.  After all, it's the music, not the perfection of
the audio reproduction, which should matter.

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