[vorbis] MP3/Vorbis comparision

[Frank Grotelueschen]

al goldstein wrote:
>I may not be sensitive to changes of a few db above 10kHz.  I'm wondering
>how the following tests would turn out. Record pink noise. Play it back as
>wav file. Encode it in various ways and play it back. Look at these playbacks
>througn a spectrum analyser. Now change your sound card and see how the
>results change.

Ok
1. I've generated white (not pink!) noise, 5 sec long with -6dB level.
2. encoded this file with "oggenc" q3 up to q7
3. decoded them with "oggdec" back to wav.
4. made a frequency analysis over the uncompressed original and
   frequancy analysis over the compressed and decompressed files.

Result:
With quality 3, 4 and 5 an high frequency boost at 10 kHz and higher
is clearly visible. Quality 6 and 7 are ok, frequency response is flat.

All files, wav, ogg, and gifs from frequency analysis are here:

http://home.t-online.de/home/520022073876/ogg01-whitenoise.zip

Filesize is around 5.1 MB.
In the gifs, i have the marked the area with high freqquencies boost.

<p>Al:

Why i should change my sound card?
I have testest all files with the SAME soundcard. The soundcard has
nothing to do with the problems with ogg.

Frank

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