Subject: Re: Fwd: Re: Re[2]: [linux-audio-dev] peakfiles and EDL's
From: Robert Schrem (Robert.Schrem_AT_WiredMinds.de)
Date: Thu Mar 01 2001 - 22:37:52 EET
On Thursday 01 March 2001 21:08, Tom Pincince wrote:
> > true. and it has me thinking that computing the RMS value for the
> > window would actually be a lot nicer in many ways than using peak
> > values. the only problem i can see is that the peak values preserve DC
> > offsets, whereas a single RMS value does not, and this could be a
> > problem. but given that any sampled audio sound is really being stored
> > as a series of amplitudes, it somehow seems more fitting to actually
> > use something more like RMS than peak data ...
> >
> >
> > any comments ?
>
> An RMS display would reduce the visual presence of transient peaks.
> Since one of the main uses of waveform overview display is to assist the
> user in knowing where he is in a song, and there is nothing better than
> transient peaks to identify location in a song (its called the beat), I
> would definitely want peak display when doing the cut and paste thing.
Maybe we could also develop an algorithm that even emphasizes
interesting frequencies... Like an option in samplitude
(see http://www.sekd.com) where the color of the pixels tell you
something about the spectral type of signal:
Red peak's for areas with dominating low frequencies and blue
for the higher frequencies. The intensity of the colour (the distance
from gray) would be controlled by the distance to an white noise
signal (a gray peak would mean a white nois signal, a very colourful
peak would mean a pure sine wave)...
There are several things you could think of for enhancing the
waveform display (if you got enougth computing power :)
> There is another time when waveform overview displays come into use that
> would definitely benefit from RMS values, and that is mastering. In
> this case the individual songs are complete and there will not be any
> defining of regions which do benefit from peak display. Instead the
> timeline of the entire project is displayed and the songs are positioned
> relative to each other. In this mode the most valuable information is
> the relative loudness of adjacent songs, and peak displays are terrible
> at this. An RMS overview would give a clearer picture when setting gain
> and eq for the purpose of making one song flow nicely into the next.
> One possible feature for this mode of display is linking gain
> adjustments from the mixer to vertical zoom in the waveform overview
> display. What you see is what you hear. I have not seen this feature
> implemented anywhere.
I completly agree on that. This would be a unique feature!
> So I guess that I would like to see an overviewfile instead of a
> peakfile, where each N samples are represented by 3 pieces of info; the
> largest + peak, the largest - peak, and the RMS value.
And probably some additional parameters...
robby
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