--- In Walter Knapp <>
wrote:
>Next, examine exactly the gain used on the mp3 and original. This
has a
>very strong bearing on the resulting display.
I did not change the gain between the two examples. Also, the
spectrogram contrast was not changed.=20=20
>It's a test of how well mp3 handles sharp high frequency transients,
>waveforms that closely resemble clipping artifacts and so on. Looks
a
>lot like a square wave generator was used to generate a lot of the
>original. To assume this bears any resemblance to natural sound is
>interesting in what it tells about people.
Such sharp transients are often present in animal sounds (e.g. some
song birds or grasshoppers). There is no clippng involved! At least
not at the upper edge of the dynamic range. But there is of course
some kind of clipping at the bottom edge of the dynamic range. This
is the 'magic' behind the both the ATRAC and MP3 systems. Hopefully,
would will understand this correctly.
The original test file was generated using a flexible sine generator
(and noise generator). That special software can also be used to
generate very naturalistic animal sounds. Download the demo version
of Avisoft-SASLab Pro from:
www.avisoft.info/downloa_.htm (first item)
Go to Edit/Synthesizer/"Synthesizer(graphically)" and select
File/Load and press the play button. You will hear a synthesized
song of the European Nightingale. Also use the mouse to modify some
of the elements and play it back again. Unfortunately, there is no
MAC version, but you could use the Virtual PC software to emulate
Windows.
I used these very artificial sound structures to make the effects
more visible on a spectrogram. I could also prepare some more
natural sounds. I will do this soon. However, I'm afraid that you
will still find many additional hair-splitting arguments to
disrespect my demonstrations It seems to be some kind of religious
believe, that lead to that ignorance (I'm very sorry for this strong
comment). I should therefore better respect this religious minority
and break off any further public criticism...
Please also note, that I'm not one of those fat and neglected
computer freaks, who never leave the laboratory. I do practise
animal sound recording in the field too (for those who care about
that)!
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