
AudioCapture |
ptolemy.actor.lib.javasound.AudioCapture |
This actor sequentially outputs audio samples that are captured
from the audio input port of the computer. The audio input port
typically corresponds to either the microphone input, line-in,
or cd audio from the cdrom or dvd drive. It is not possible to
select the desired input port under Java. This must be done from
the operating system. This actor should be fired often enough to
prevent overflow of the internal audio capture buffer.
Overflow should be avoided, since it will result in loss of
data. Each captured audio sample is converted to a double that
may range from -1.0 to 1.0. Thus, the output type of this actor
is DoubleToken.
<p>
The following parameters should be set accordingly. In all cases,
an exception is thrown if an illegal parameter value is used.
Note that these parameters may be changed while audio playback
is active. If this actor is used in conjunction with an
AudioPlayer actor, changing a parameter will cause the corresponding
parameter value of the AudioPlayer to automatically be set to the
same value. This behavior is required because the AudioCapture and
AudioPlayer actors both share access to the audio hardware, which
is associated with a single sample rate, bit resolution, and
number of channels.
<ul>
<li><i>sampleRate</i> should be set to the desired sample rate, in Hz.
The default value is 8000. Allowable values are 8000, 11025,
22050, 44100, and 48000 Hz. Note that Java does not support
96000 Hz operation, even if the audio hardware supports it.
<li><i>bitsPerSample</i> should be set to the desired bit
resolution. The default value is 16. Allowable values are 8 and 16.
Note that Java does not support 20 or 24 bit audio, even if the
audio hardware supports it.
<li><i>channels</i> should be set to desired number of audio
channels. The default value is 1 (for mono audio). Allowable
values are 1 and 2 (for stereo). Note that more than two
channels of audio is not currently supported in Java, even if
the audio hardware supports it.
</ul>
<p>
It should be noted that at most one AudioCapture and one AudioPlayer
actor may be used simultaneously. Otherwise, an exception will
occur. This restriction may be lifted in a future version of
this actor.
<p>
There are security issues involved with accessing files and audio
resources in applets. Applets are not
allowed to capture audio from the audio input port (e.g., the
microphone) by default since this could present a security risk.
Therefore, the actor will not run in an applet by default. The
.java.policy file may be modified to grant applets more
privileges.
<p>
Note: Requires Java 2 v1.3.0 or later.
Author(s): Brian K. Vogel, Christopher Hylands, Steve Neuendorffer
Version:$Id: AudioCapture.doc.html,v 1.1 2006/02/22 18:40:26 mangal Exp $
Pt.Proposed Rating:Yellow (vogel)
Pt.Accepted Rating:Yellow (chf)
trigger
The trigger port.
output
The output port. This will always produce double data,
between -1.0 and 1.0.
output_tokenProductionRate
The output rate.