audio.cpp

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// PTF - Psychological Test Framework
// http://ptf.sourceforge.net
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Library General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

#include <ptf/environment/audio.hpp>
#include <ptf/core/ptfcore.hpp>
#include <stdexcept>

Audio::Audio() {
    // initialize audio system
    // open 44.1KHz, signed 16bit, system byte order, stereo audio, using 1024 byte chunks
    if (Mix_OpenAudio(44100, MIX_DEFAULT_FORMAT, 2, 1024) == -1) {
        PtfCore::getSingleton().getMessageLog() << ERROR("Audio system failed to initialize.\n");
        throw std::runtime_error("Audio system failed to initialize.");    
    }
    else {
        PtfCore::getSingleton().getMessageLog() << MESSAGE("Audio system initialized.\n");
    }
    // allocate 4 mixing channels
    Mix_AllocateChannels(4);
    // set all channels to half volume
    Mix_Volume(-1, MIX_MAX_VOLUME/2);
}

Audio::~Audio() {
    // delete samples
    for (int i = 0; i < (int)samples.size(); i++) delete samples[i];
    // close audio
    Mix_CloseAudio();
}

int Audio::addSample(char* fname) {
    Mix_Chunk* sample;
    sample = Mix_LoadWAV(fname);
    if(sample == 0) {
        PtfCore::getSingleton().getMessageLog() << "ERROR:   Failed to load an audio sample (" 
            << fname << ").\n";
        throw std::runtime_error("Failed to load an audio sample.");    
    }
    else {
        samples.push_back(sample);
        return (int)samples.size();
    }
}

void Audio::playSample(int index) {
    if (index >= (int)samples.size() || index < 0) {
        PtfCore::getSingleton().getMessageLog()
             << "ERROR:   Sample doesn't exist (number " << index << ").\n";
        throw std::runtime_error("Sample doesn't exist.");
    }
    // play desired sample once using first free channel
    if (Mix_PlayChannel(-1, samples[index], 0) < 0) {
        PtfCore::getSingleton().getMessageLog() << "ERROR:   Failed to play an audio sample. \n";
        throw std::runtime_error("Failed to play an audio sample.");    
    }
}

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