Subject: [linux-audio-dev] metering, patent avoidance: please disseminate this
From: Paul Barton-Davis (pbd_AT_Op.Net)
Date: pe maalis 03 2000 - 11:30:00 EST
Please copy this message to wherever you think appropriate so that it
can act as prior art in the event that anyone attempts to patent this
idea. Note that the source code can be found at ardour.sourceforge.net.
This idea was originally described by Bill Gribble, and implemented by
Paul Barton-Davis, as part of the "ardour", a multitrack audio
recording program.
A metering system to allow the detection and display of
sequential out of range values
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Conventional metering systems either do not offer any special
facilities for displaying out-of-range values, or do so using a "peak
hold" facility that displays an indicator of the largest recorded
signal over some time duration. Although there are variations in the
exact methods used to display out-of-range values, all existing
methods share in common the fact that unless the peak measurement is
displayed indefinitely, if an observer is not looking at the meter
during the right time period, they will not see the display showing
out of range values.
Furthermore, existing metering systems typically do not offer any
method of displaying the temporal duration for which the out of range
values were detected by the meter. This can be significant since in
some cases, 1 or 2 sequential out of range values do not represent a
situation in which any action is necessary. By contrast, one in which
10 or more such values were detected may require action on the part of
the meter user.
The metering system implemented in ardour provides "peak hold" like most
other metering systems, but it also provides at least two display
counts. These counts reflect the number of times that a sequence of
out-of-range values of a certain length or longer was detected during
some time period, typically since the last "meter reset". The lengths
are adjustable by the user. So, for example, if there are 2 counts
display, and the lengths are set to 3 and 10, then: one of the numbers
displayed will show the number of times that a sequence of
3 or more consecutive out-of-range values was detected since the last
meter reset; the other will show the same information for sequences of
10 or more consecutive out-of-range values.
This metering system allows the meter user to be looking at something
else or be away from the meter while it is used, and then upon
returning his/her attention to it, to discover whether any
out-of-range sequences occured, and if so how many.
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