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Subject: Re: AW: Question about CD-Quality and MP3

Re: AW: Question about CD-Quality and MP3

From: Michael E. DiFebbo <medifebbo_at_rcn.com>
Date: 2006-02-02

Christi Alice Scarborough wrote:
> Annecdotally I can tell you that a friend lent me some 192kpbs MP3s
> that I listened to for a while before buying the album. I could hear
> enough difference on the CD that at first I thought I was listening to
> a different mix of the album, which I certainly wasn't expecting.
> This was via my stereo though - I believe the difference is less
> detectable when listening on earphones.
>
> Christi
>
It's possible that what you were hearing was a poorly encoded MP3. Also
anecdotally, I used to think that 128kbps was terrible and that I could
always tell the difference between 128kbps and the original. When I did
an ABX test using 128kbps MP3s encoded with LAME 3.97b1, I was surprised
to find that it was very difficult for me to hear the difference. I
could do it, but not with 100% consistency and not easily. I then
realized that all of the 128kbps MP3s that I thought sounded bad were
encoded with an older version of the Xing encoder, and that what I was
hearing on those MP3s was the result of that encoder rather than any
inherent limitation in the MP3 format.

I then did a series of ABX tests between an uncompressed .wav file and
MP3s encoded with LAME 3.97b1's -V5 setting, which yields VBR files
averaging about 130kbps. (This setting will use bitrates of up to
224kbps for frames that require it, but lower bitrates for frames that
do not.) I found that I cannot differentiate the -V5 MP3 from the
original.

I had previously been using LAME 3.97b1 -V2 for portable use, which
yields files that average somewhere between 180 and 205kbps. After my
ABX tests, I started using the -V5 setting for portable use instead, to
save space.

Michael E. DiFebbo
_________________________________________

http://www.jumpcityjazz.com
Received on Thu Feb 2 12:55:47 2006


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