[vorbis] mp3-wav-cd-audio "acoustically equivalent" to wav-cd-audio ?

Andy Dale andycool22 at peoplepc.com
Fri Aug 31 03:55:28 PDT 2001



sorry i meant to say 128kbits joint stereo is still lossy, but i personally
can't tell and i personally think i have sensitive ears.  i can tell however
if i turn on an equalizer or normalizer because that bumps up any treble or
bass areas and lets you hear the lossy parts more easily (such as cymbal
crashes sounding watery)

Andy (Dale)
andycool22 at peoplepc.com
AndyCool22 on AIM
http://livejournal.com/~andycool22
----- Original Message -----
From: "Andy (Dale)" <andycool22 at peoplepc.com>
To: <vorbis at xiph.org>
Sent: Friday, August 31, 2001 6:52 AM
Subject: Re: [vorbis] mp3-wav-cd-audio "acoustically equivalent" to
wav-cd-audio ?

i would say offer something like monkey's audio (lossless) and mp3 or ogg
(at least 128kbits, and mp3 make sure it is joint stereo, i can notice sound
degradation if it is stereo).  this way both formats would be compressed but
you would still have a lossless format.  the only way i know that an 128kbit
joint stereo mp3 is lossless is if i unplug a speaker plug halfway, i get
like the background sound (if you have a sound card that offers a "stereo
wide" option in the volume control, this is what i hear.  peace

Andy (Dale)
andycool22 at peoplepc.com
AndyCool22 on AIM
http://livejournal.com/~andycool22
----- Original Message -----
From: "Marshall Eubanks" <tme at 21rst-century.com>
To: "Yusuf Goolamabbas" <yusufg at outblaze.com>; <vorbis at xiph.org>
Sent: Friday, August 31, 2001 5:51 AM
Subject: Re: [vorbis] mp3-wav-cd-audio "acoustically equivalent" to
wav-cd-audio ?

>A friend of mine made the following comment in a discussion I had with
>him that on a website we adminster we should offer
>
>a) WAV or maybe shorten files
>b) Ogg as a decent reference lossy encoded version
>
>He's been trying to convince me that we should offer MP3 (in lieu of
>WAV) and possibly Ogg.
>
>The audio files are primarily vocals
>
>I am not a physics guy but his statements don't intuitively feel right.
>Maybe he has a misunderstanding which can be clarified
>
>Regards, Yusuf
>----------------------------------------------------------------------
>regarding WAV, we used to store the masters on the disk, but moved them
>offline due to space concerns. If a user downloads the MP3 and creates a
WAV

>from it, that is going to be precisely equivalent on the audio CD in
>quality. I have tested it myself in MATLAB using spectral and phase
analysis

>(I am a physics guy, after all).

IMHO, as a professional physicist, he has no clue.

MP3 is a lossy encoding. That means you lose something.
At a low bit rate, you tend to lose a lot.
Just try doing this at 32 kbps stereo and you _will_
notice the acoustic nonequivalence.

Regards
Marshall Eubanks

>
>recite WAV -> MP3 -> WAV -> CD Audio is *acoustically equivalent* to recite

>WAV -> CD audio.
>
>to confirm, Perform this experiment at home (I have done so)
>
>1. recite to WAV. save as A.wav
>2. encode A.mp3 from A.wav
>3. create B.wav from A.mp3.
>4. ask someone to burn A.wav and B.wav to an audio CD (double blind -
>neither you, nor they, shoudl know which is which).
>5. listen to the CD in a standard player. You will hear zero differrence in

>sound quality.
>
>I am NOT saying,  not to make WAV available. But I am pointing out that the

>vast majority of repackagers only want to create CDs. And that they will
not

>be able to improve upon the sound quality , though it is quite possible
they

>may degrade it, during their own post-processing stages. We can safely
>assume that most repackagers will choose to go the easy route, and we can
>easily have a note saying "true WAV masters for many audio files are
>available for more advanced processing. Please contact Webmaster etc etc".

>
>as an aside - there are already several excellent freeware tools which
allow

>you to create playlists of MP3 files and burn them straight to audio CD,
>doing the WAV interpolation for you directly. No such tools yet exist for
>OGG of course, but they too will come in a year or so (the ones I have seen

>for OGG are still quite unstable - if it doesnt come from vorbis.com, I
dont

>trust it).
>
>----------------------------------------------------------------------
>
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>

Marshall Eubanks

tme at 21rst-century.com

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