[vorbis] MP3/Vorbis comparision

[Frank Grotelueschen]

Giuliano Pochini wrote:

>-q6 I can't see it anymore. That means lossy stereo coupling has
>something to do with high frequency boost. I had no time to test all

Yes, i think so also.

>There is another fact that can be quite annoiyng. My noise samples
>were at half amplitude (-16K/+16K). After I encoded/decoded them,
>the amplitude was a lot higher than that. I can see it in the background
>window of your spectrograms too. It happens up to -q6. IMHO it's caused
>by the way vorbis encodes (lossy) phase informations.

When high frequency boost accur, a increased amplitude is visible.
This is normal and no extra problem.
The Y-graph in the background windows shows +/-32K (the max. amount for
16 bit resolution). This graph is linear, not logarithmic. For example,
a increase of only 2dB at 16K will give this result:
   20,1K = 16K * 10^(2dB/20)
This is very visible in this graph, even when not the whole frequency
spectrum is boosted.

>Well, noise is noise... the only interesting thing are the graphs :)

Ok, but i had included all files, if somebody want to check my results
with my own files.

Frank

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