[LAU] How bad is mp3/ogg

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To: <linux-audio-user@...>
Date: Tuesday, October 11, 2011 - 8:58 pm

Hi

I'm teaching a course in electronic music, and one of the subjects I'd
like to cover is what compression does to the music. I googled a bit abd
found this:

http://www.youtube.com/watch?v=u5gdwpPrv_8

Basically it's a matter of loading the original + the mp3 encoded
version of the same track, inverting the phase in one of the two clips
and listening to the artifacts.

I did some tests, and the results are scary. Lame (128 kbps)and oggenc
(q=3) are different but both horrible, the artifacts are very ugly and
distorted and are as loud as -19 dB!. My favorite mp3 encoder, gogo, has
another strange result: The artifacts sound almost like the mp3, which
should mean it changes the audio much more! However I don't really hear
that much difference between lame and gogo encoded files...

This got me thinking if this is even a realistic test. Assume for
instance the encoder introduces a simple, constant delay in the encoded
audio. This will result in a lot of sound slipping through the
invert-the-phase-of-one-of-the-signals test. Although it could be said
it alters the audio dramatically, when aligning the files and comparing
them sample for sample, it has no impact on the perceived quality of the
encoded audio. I didn't fiddle with delaying the gogo encoded file, though.

My question is: is this really a fair way to judge the artifacts
introduced by encoding?

--
Atte

http://atte.dk http://modlys.dk
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Messages in current thread:
[LAU] How bad is mp3/ogg, Atte André Jensen, (Tue Oct 11, 8:58 pm)
Re: [LAU] How bad is mp3/ogg, Jostein Chr. Andersen, (Tue Oct 11, 9:57 pm)
Re: [LAU] How bad is mp3/ogg, Fons Adriaensen, (Tue Oct 11, 9:07 pm)
Re: [LAU] How bad is mp3/ogg, Hartmut Noack, (Wed Oct 12, 3:09 pm)
Re: [LAU] How bad is mp3/ogg, david, (Wed Oct 12, 4:03 pm)
Re: [LAU] How bad is mp3/ogg, Hartmut Noack, (Wed Oct 12, 4:31 pm)
Re: [LAU] How bad is mp3/ogg, Fons Adriaensen, (Wed Oct 12, 5:09 pm)
Re: [LAU] How bad is mp3/ogg, Jostein Chr. Andersen, (Wed Oct 12, 7:09 pm)
Re: [LAU] How bad is mp3/ogg, Fons Adriaensen, (Wed Oct 12, 7:45 pm)
Re: [LAU] How bad is mp3/ogg, Philipp Überbacher, (Wed Oct 12, 10:10 pm)
Re: [LAU] How bad is mp3/ogg, Hartmut Noack, (Wed Oct 12, 9:03 pm)
Re: [LAU] How bad is mp3/ogg, Monty Montgomery, (Wed Oct 12, 9:31 pm)
Re: [LAU] How bad is mp3/ogg, Hartmut Noack, (Thu Oct 13, 5:48 pm)
Re: [LAU] How bad is mp3/ogg, Egor Sanin, (Thu Oct 13, 10:53 am)
Re: [LAU] How bad is mp3/ogg, S. Massy, (Tue Oct 11, 9:34 pm)
Re: [LAU] How bad is mp3/ogg, Lorenzo Sutton, (Wed Oct 12, 12:40 pm)
Re: [LAU] How bad is mp3/ogg, Charles Henry, (Wed Oct 12, 2:46 pm)
Re: [LAU] How bad is mp3/ogg, , (Wed Oct 12, 2:26 pm)
Re: [LAU] How bad is mp3/ogg, Kevin Cosgrove, (Wed Oct 12, 2:33 pm)
Re: [LAU] How bad is mp3/ogg, Monty Montgomery, (Wed Oct 12, 2:30 pm)
Re: [LAU] How bad is mp3/ogg, S. Massy, (Tue Oct 11, 10:22 pm)
Re: [LAU] How bad is mp3/ogg, Philipp Überbacher, (Wed Oct 12, 10:20 am)
Re: [LAU] How bad is mp3/ogg, S. Massy, (Wed Oct 12, 9:57 pm)
Re: [LAU] How bad is mp3/ogg, Monty Montgomery, (Wed Oct 12, 10:08 pm)
Re: [LAU] How bad is mp3/ogg, S. Massy, (Wed Oct 19, 7:00 pm)
Re: [LAU] How bad is mp3/ogg, Monty Montgomery, (Tue Oct 11, 10:56 pm)
Re: [LAU] How bad is mp3/ogg, Folderol, (Wed Oct 12, 7:34 pm)
Re: [LAU] How bad is mp3/ogg, Monty Montgomery, (Tue Oct 11, 10:52 pm)
Re: [LAU] How bad is mp3/ogg, Al Thompson, (Wed Oct 12, 5:34 am)
Re: [LAU] How bad is mp3/ogg, S. Massy, (Wed Oct 19, 6:58 pm)
Re: [LAU] How bad is mp3/ogg, Fons Adriaensen, (Wed Oct 19, 7:23 pm)
Re: [LAU] How bad is mp3/ogg, Atte André Jensen, (Tue Oct 11, 9:18 pm)
Re: [LAU] How bad is mp3/ogg, Joe Hartley, (Wed Oct 12, 12:18 pm)
Re: [LAU] How bad is mp3/ogg, Fons Adriaensen, (Tue Oct 11, 9:36 pm)
Re: [LAU] How bad is mp3/ogg, Atte André Jensen, (Tue Oct 11, 9:42 pm)
Re: [LAU] How bad is mp3/ogg, Moshe Werner, (Tue Oct 11, 10:28 pm)