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<DIV><FONT face=Arial size=2>First a comment, then back to the original problem:
a</FONT><FONT face=Arial size=2>ctually, the file sizes ARE different... I have
tested it, using a single WAV source (Mozartīs 25th symphony in D Minor, if that
is of any interest...). MP3 files are smaller than wma, and ogg smaller than
both the others. I used dBpower AMP, and it indicated the supposed bit rate for
the ogg files. All conversions using CBR, even for ogg; the VBR files were
smaller still, but I guess that was expected.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>OK, I got the idea about bit rate, and I understand
that it can't be compared across formats. So, the big question now is, is there
a way to compare the results? Lets think of something like creating different
music files, and comparing them back to the original DIGITALLY; can you
calculate in any way which file is closer to the original? BTW, is this a good
indication of sound quality (a MP3 might for instance catch ALL the silence
perfectly, thereby being "closer" to the original in some way, even if it does
not render a good sound...)? How about dividing the analysis into different
frequency levels?</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Its not that difficult to imagine a way, its just
the goode-ole square differences. Calculate the differences between source and
converted file, square and add it up. The file with the lower sum is the best
conversion... I understand there is a problem there because of the bit rates
(most of the comparison would be between music on the original and nothing on
the lossy file). You could convert the lossy back to wav, but then results
depend on the lossy-to-WAV decoder.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Anyway, I guess you got the picture. ok, it depends
on ear sensibility, the price of your equipment, and so on. But in the end, its
all zeroes and ones. There SHOULD be a way to compare the results when using
different formats/bit rates/settings... I just can't find it
anywhere!!</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Rodrigo</FONT></DIV>
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=graham@grahammitchell.com
href="mailto:graham@grahammitchell.com">Graham Mitchell</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=rodrigo@escobar.com
href="mailto:rodrigo@escobar.com">Rodrigo Escobar Nunes</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Tuesday, September 28, 2004 12:44
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [Vorbis] Bit rates, files
size</DIV>
<DIV><BR></DIV>> Does anybody has any idea how to compare mp3, wma and ogg
in terms <BR>> of bit rate and quality? I mean, I have tested it and the
ogg files <BR>> are always smaller if you set the same bit rate as compared
to the <BR>> other two, and smaller still if u use VBR. But how about
quality? Is <BR>> a 160bps ogg comparable to a what in a mp3? The same bit
rate, lower,<BR>> higer?...<BR><BR>Looks like you haven't read my
"Introduction to Compressed Audio with Ogg<BR>Vorbis". :)<BR><BR><A
href="http://grahammitchell.com/writings/vorbis_intro.html#just_say_no_to_bitrates">http://grahammitchell.com/writings/vorbis_intro.html#just_say_no_to_bitrates</A><BR><BR>In
short, you're trying to compare apples and oranges. A 128 kbps mp3 will
be<BR>the SAME size as a 128 kbps Ogg Vorbis file, and as a 128 kbps WMA,
because<BR>the size of a file is determined by its bitrate (and
length).<BR><BR>And to compare quality, I'd need to know what encoder you're
using for your<BR>mp3s. A 128 kbps mp3 encoded with the Xing encoder or
BladeEnc sounds pretty<BR>terrible, whereas one with the LAME mp3 encoder
sounds fairly decent.<BR><BR>In any case, Ogg Vorbis beats mp3 at any
bitrate. Vorbis audio at 96 kbps<BR>sounds as good as most 128 kbps
mp3s, in my opinion. Vorbis audio at 112 kbps<BR>sounds slightly better
than your typical 128 kbps mp3.<BR><BR>Vorbis audio at 160 kbps would be
comparable to at least 192 kbps mp3, I'd<BR>say. But again, it's like
saying "my Porsche at 5000 RPMs is as fast as a<BR>Mustang at 6000
RPMs." Just like talking about RPMs when you really mean<BR>speed is
silly, it's silly to talk about bitrates when you really mean
sound<BR>quality. Vorbis sounds better at a smaller file size.
Bitrate is a measure<BR>of file size, not quality.<BR><BR>WMA also sounds
better than mp3, but then this isn't the WMA mailing list, is it?<BR><BR>--
<BR>Graham Mitchell - computer science teacher, Leander High
School<BR></BLOCKQUOTE></BODY></HTML>