Examples of ptolemy.media.javasound.SoundPlayback

A buffer supporting the playback of audio data and the the writing of audio data to a sound file.

Overview

A buffer supporting the real-time playback of audio and the writing of audio data to a sound file. Single channel (mono) and multichannel audio (stereo) are supported. This class, along with SoundCapture, intends to provide an easy to use interface to Java Sound, Java's audio API. Java Sound supports the writing of audio data to a sound file or the computer's audio output port, but only at the byte level, which is audio format specific. This class, however, provides higher level support for the writing of double or integer valued samples to the computer's audio output port or any supported sound file type. This class is therefore useful when it one desires to playback audio samples in an audio format independent way.

Depending on available system resources, it may be possible to run an instance of this class and an instance of SoundCapture concurrently. This allows for the concurrent capture, signal processing, and playback of audio data.

Usage

Two constructors are provided. One constructor creates a sound playback object that sends audio data to the speaker. If this constructor is used, there will be a small delay between the time that the audio data is delivered to this object and the time that the corresponding audio is actually heard. This latency can be adjusted by setting the bufferSize constructor parameter. Another constructor creates a sound playback object that sends audio data to a sound file.

After calling the appropriate constructor, startPlayback() must be called to initialize the audio system. The putSamples() or putSamplesInt() method should then be repeatedly called to deliver the audio data to the audio output device (speaker or file). The audio samples delivered to putSamples() should be in the proper range, or clipping will occur. putSamples() expects the samples to be in the range (-1, 1). putSamplesInt() expects the samples to be in the range (-2^(bits_per_sample/2), 2^(bits_per_sample/2)), where bits_per_sample is the number of bits per sample. Note that it is possible (but probably not useful) to interleave calls to putSamples() and putSamplesInt(). Finally, after no more audio playback is desired, stopPlayback() should be called to free up audio system resources.

Security issues

Applications have no restrictions on the capturing or playback of audio. Applet code is not allowed to write native files by default. The .java.policy file must be modified to grant applets more privileges.

Note: Requires Java 2 v1.3.0 or later. @author Brian K. Vogel @version $Id: SoundPlayback.java,v 1.60 2007/12/06 18:30:03 cxh Exp $ @since Ptolemy II 1.0 @Pt.ProposedRating Yellow (vogel) @Pt.AcceptedRating Yellow (cxh) @see ptolemy.media.javasound.SoundCapture