Programmer Guide/Command Reference/EVAL/aseg1

This function implements a simple automatic signal segmentation based on the energy (rms) track of the signal.

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Usage 1

aseg1(x, 0, n, m, xmin, omax)

x

data vector (usally rms track in dB)

n

minimum length of a signal segment in frames; 0 < n < nrow(x)

m

smoothing length; 0 <= m; if m is greater than zero, the segmentation is performed on a smoothed data vector xs.

xs[i] = avr(x[i-m], .., x[i+m]); with: i=0..nrow(x)

xmin

segment threshhold

omax

offset for segment center; 0 < omax

Description

1. A segment is a continuous range of x, where all values are greater than xmin
2. The center of a segment is a continuous range of values inside a segment, where all values are greater than xmax-omax (with: xmax is the maximum value inside the segment).

Result 1

A matrix r with 4 rows. Each column of r defines one segment. Note that all values of r are frame indices (or row indices) of the data vector x.

r[0,i]	beginning of the segment i
r[1,i]	beginning of the center of the segment i
r[2,i]	end of the center of the segment i
r[3,i]	end of the segment i

with: i=0..nrow(r)

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Usage 2

aseg1(x, 0, n, m, xmax, xmin)

x

data vector (usally rms track in dB)

n

minimum length of a signal segment in frames; 0 < n < nrow(x)

m

smoothing length; 0 <= m; if m is greater than zero, the segmentation is performed on a smoothed data vector xs.

xs[i] = avr(x[i-m], .., x[i+m]); with: i=0..nrow(x)

xmax

maximum threshold; the maximum value of a segment must be greater than xmax

xmin

minimum threshold; all values of a segment must be greater than xmin

Description

segment detection:

1. find a position i with x[i]>xmax
2. go backward while x[i-j]>xmin; last index i-j is the segment begin
3. go forward while x[i+k]>xmin; last index i+k is the segment end

Result 2

A matrix r with 2 rows. Each column of r defines one segment. Note that all values of r are frame indices (or row indices) of the data vector x.

r[0,i]	beginning of the segment i
r[3,i]	end of the segment i

with: i=0..nrow(r)

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