Paul Foxworthy wrote:
> At 11:11 26/10/2000 +1100, John Boyce wrote:
> >recall. Using an mp3 player (such as a compaq ipaq handheld pda) you
> >could already have 10 sec or so for each bird and the sound would be
> >retreivable in a few seconds. Only available RAM is holding us back.
> There are MP3 players with 64 Mbyte of RAM available now, and if that's not
> enough, others have multi-gigabyte matchbox-sized hard disk drives.
There are also portable CD players that will also play MP3 files
stored on CD-R (and possibly CD-RW) disks.
One thing that should be pointed out is that MP3 is a lossy
compression format i.e. if you decode an MP3-encoded audio file,
the resulting audio will *not* the same as the original.
(The JPEG image format also uses lossy compression.)
How well MP3 works in practice depends upon the how accurate the
psychoacoustic model is, which is partially dependent on how much
accuracy you are prepared to sacrifice for better compression.
(The psychoacoustic model determines which parts of the original
audio cannot be "heard", and can be discarded to obtain greater
compression.) I suspect that birdcalls may show more artifacts
as a result of compression than music, because it tends to
contain more information at higher frequencies(?) If I find
some spare time, I may try converting some samples of birdcalls
from CD to MP3, and see if I can hear any difference. (I've also
located some tools to visually show the differences in the signals
before and after compression, and analyze the distortion etc.)
Paul Taylor Veni, vidi, tici -
I came, I saw, I ticked.
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