doi
/
NHP-pRF
sklonowany z ChrisKlink/NHP-pRF


			
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    <h1>wave_browser help</h1>
<p>
<ul>
 <li><a href="#overview">Overview of wave_browser</a></li>
 <li><a href="#load">Loading wav files</a></li>
 <li><a href="#navigate">Navigating a wav file</a></li>
 <li><a href="#segment">Segmenting a wav file</a></li>
   <ul>
     <li>Defining a segment manually</li>
     <li>Automatically segmenting</li>
     <li>Saving segments to a file </li>
     <li>Loading segments from a file</li>
   </ul>

 <li><a href="#configure">Configuring spectral parameters</a></li>

 </ul>

 <hr>

<h2><a name="overview"/>Overview of wave_browser</h2>

<p>Wave_browser is software for reading in a wav file and segmenting
the wav file into segments. Segments can be manually defined or can be
computed automatically. The software generates a seg.txt which defines
the beginning and the end of each segment in the wav file.</p>

<p>To assist the user in defining segments the wave_browser plots the
wave form, the summed intensity or power, and the spectragram of the
audio. The spectragram is computed using a multitaper approach. </p>

<h2><a name="load"/>Loading wav files</a></h2>

<p>In order to segment a wave file the file must be first
loaded. Clicking the <b>Load</b> button will open the file dialog
window. By default the file dialog will show only files having a
".wav" extension. Wav files without the extension can also be loaded
from this file dialog. A requirement is that the wav file be a single
audio track (mono) and not include two tracks (stereo) or more. The
sampling rate of the wav file can be variable. The higher the sampling
rate the better the quality of the audio. As a standard CD quality
audio is sampled at 44100 Hz. The software will automatically detect
the sampling frequency. If the file is loaded successfully it will
show three visual representations of the audio in the file.</p>

<p>To load the next unsegmented wave file click the <b>Load Next</b>
button. This feature increases the work-flow speed when a directory of
files are being manually segmented by a user, and prevents the user
from segmenting a wav file that already been segmented.</p>

<h2><a name="view"/>Viewing the wav file</h2>

<p>There are three distinct views of the wave file. Starting from the
bottom, the bottom plot is the wave form over the time range. The
middle plot is the spectragram which shows how intensity of different
frequencies of sound change over time. The top view is the intensity
of the spectragram summed at each moment in time or power. The red
lines in the plot shows where the autosegmenter would segment the
file. A segment is defined as where the red line is at the maximum
intensity.  The beginning and end of the segment are demarcated by red
vertical lines. The height of the horizontal line between segments is
determined by the <b>Amplitude Threshold</b> entry box. </p>

<p>There are three types of spectragrams that can be plotted. By
default the <b>Spectrum Type</b> is <b>Original</b>. Often it is
useful to compute a derivative of the original spectragram. The
derivative can be computed in different directions, but is usually
computed in just two directions The first direction is in terms of the
frequency. This shows how the intensity of the original spectragram
changes in the direction of the frequency (up and down). The second
direction is in terms of time (left to right). The <b>Time
Derivative</b> and <b>Frequency</b> derivative spectragrams are
selected from the drop-down menu. In order to compute the selected
spectragram click the <b>Plot</b> button. The derivatives of the
spectragram are plotted in gray-scale. </p>

<p>The <b>Display Window</b> entry-box controls how much of the wav file
is plotted. This parameter is user settable in seconds. The <b>Plot
All</b> button sets the display window to the entire duration of the
wav file and updates the plots of the wav file. This functionality is
useful for autosegmenting an entire wave file.</p>

<img width="719" height="396" src="wave_browser-main-scaled.png">

<h2><a name="navigate"/>Navigating a wav file</h2>

<p>If the <b>Display Window</b> is set to less than the duration of
the wave file to view the entire wave requires the ability to navigate
around the wav file.  The <b>Jump</b> button moves the current display
window forward in time. While the <b>Jump Back</b> moves the display
window backward in time. Each button also recomputes the spectragram.
For forward and backward jumps the display window is not allowed to
exceed the duration of the wave file. In the forward case the end of
the display window is set to the end of the file, and in the back case
the beginning of the window is set to the beginning of the wave
file.</p>

<p>Depending on the speed of the processor and the size of the display
window navigating a wave file can be time consuming. At each jump the
spectragram is recomputed.  If the user is not going to change the
parameters during navigation the <b>Precompute</b> toggle button can
speed up the process of navigation. The <b>Precompute</b> button
computes the spectragram for the entire duration of the file and
caches the results in memory. Rather than recomputing the spectragram
for each jump the stored copy is accessed. A precomputed spectragram can use a
large amount of memory. How large a wav file can be computed is
determined by the step size of the spectragram and the amount of physical
memory available. In precompute mode changing the spectral parameters
are not allowed. Precompute mode can be exited by clicking the toggle
button for a second time. Exiting precompute mode will release the
memory held to store the entire spectragram.</p>


<h2><a name="segment"/>Segmenting a wav file</h2>

<p>Wave files can be segmented manually and automatically, or using a
 combination of
both methods. To begin segmenting click the <b>Segment on</b> toggle button.
The user is now in segment mode. To define where a segment starts click on the middle plot where the segment begins. This will place a vertical time marker on the spectragram. At this point the location of the time maker can be adjusted by clicking another location. Once the time marker is placed correct click the <b>Start</p>. The time marker will change to a start time marker which is thicker in width.  Now the user can set a second time marker to demarkate where the segment stops.  The <b>Stop</b> button will change the time marker to a stop marker. An X is drawn to show that the segment is now defined. The user can now define additional segments.

Segments can be saved by using the <b>Save</b> button. This will generate a *.seg.txt file. Clicking the <b>Cancel</b> button will now allow you to exit segment mode.   Segments defined previously can be loaded by clicking the <b>Load</b> button. 

<h2><a name="configure"/>Configuring spectral parameters</a></h2>

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<!-- Created: Mon May 15 15:30:19 EDT 2006 -->
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Last modified: Wed May 24 16:02:41 EDT 2006
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