Re: Fwd: Re: Re[2]: [linux-audio-dev] peakfiles and EDL's

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Subject: Re: Fwd: Re: Re[2]: [linux-audio-dev] peakfiles and EDL's
From: Tom Pincince (stillone_AT_snowcrest.net)
Date: Thu Mar 01 2001 - 22:08:47 EET


> 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.

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.

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.

Are you computing this on the fly, creating the peakfile and the
soundfile simultaneously, or are you computing the peakfile immediately
after recording is stopped? Certainly you would need the ability to
compute the peakfile for imported files, which would obviously not be
done simultaneously with recording. Computing the peakfile after
recording is stopped would allow you to include more statistical
information about the soundfile since there would be no concern
regarding rt performance. However, an immediately available waveform
overview would also be nice, and creating a peakfile containing only
peak info could probably be computed on the fly.

Tom


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