audio experiments

gistfile1.cpp

#include <cassert>
#include <cstdlib>
#include <vector>
#include <boost/intrusive_ptr.hpp>

#include <AL/al.h>
#include <AL/alc.h>
#include <vorbis/vorbisfile.h>

#include "bicycles/sp.h"
#include "gfxmath/vec.h"

class ALBuffer : public RefCounted<ALBuffer> {
public:
    ALBuffer();
    ~ALBuffer();

    void setData(ALenum format, const void *data, int size, int freq);

    ALuint getID() const
    {
        return m_id;
    }

private:
    ALuint m_id;
};

typedef boost::intrusive_ptr<ALBuffer> ALBufferPtr;

class ALSource {
public:
    ALSource();
    ~ALSource();

    void setBuffer(ALBufferPtr buf);

    void setPosition(const vec3f &pos);

    void play();
    void stop();
    int getState() const;

private:
    ALBufferPtr m_buf;
    ALuint m_id;
};

ALBuffer::ALBuffer()
{
    alGenBuffers(1, &m_id);
}

ALBuffer::~ALBuffer()
{
    alDeleteBuffers(1, &m_id);
}

void ALBuffer::setData(ALenum format, const void *data, int size, int freq)
{
    alBufferData(m_id, format, data, size, freq);
}

ALSource::ALSource()
{
    alGenSources(1, &m_id);
}

ALSource::~ALSource()
{
    alDeleteSources(1, &m_id);
}

void ALSource::setBuffer(ALBufferPtr buf)
{
    m_buf = buf;
    if (buf)
        alSourcei(m_id, AL_BUFFER, buf->getID());
}

void ALSource::setPosition(const vec3f &pos)
{
    alSourcefv(m_id, AL_POSITION, pos.data());
}

void ALSource::play()
{
    alSourcePlay(m_id);
}

void ALSource::stop()
{
    alSourceStop(m_id);
}

int ALSource::getState() const
{
    int state;
    alGetSourcei(m_id, AL_SOURCE_STATE, &state);
    return state;
}

void readOGG(const char *path, ALBuffer &buffer)
{
    OggVorbis_File file;
    int ret;

    ret = ov_open(fopen(path, "r"), &file, NULL, 0);
    assert(ret == 0);

    ALenum format;
    ALsizei freq;
    vorbis_info *info = ov_info(&file, -1);
    if (info->channels == 1)
        format = AL_FORMAT_MONO16;
    else
        format = AL_FORMAT_STEREO16;
    freq = info->rate;

    size_t size = ov_pcm_total(&file, -1) * info->channels * 2;
    std::vector<char> data;
    long bytes;
    int bitsream;
    data.reserve(size);
    do {
        char tmp[1024];
        bytes = ov_read(&file, tmp, sizeof(tmp), 0, 2, 1, &bitsream);
        data.insert(data.end(), tmp, tmp+bytes);
    } while (bytes > 0);

    buffer.setData(format, &data[0], data.size(), freq);

    ov_clear(&file);
}

double noteFreq(int note, int octave)
{
    int e = (octave*12+note)-48;
    return pow(2, (e/12.0))*261.63;
}

double getDuration(char c)
{
    return 1.0/(c-'0');
}

double getNoteFreq(char c)
{
    if (c == ' ')
        return 0;

    static const struct {
        char c;
        int note;
        int octave;
    } noteMap[] = {
        { 'D', 2, 4 },
        { 'e', 4, 4 },
        { 'f', 5, 4 },
        { 'g', 7, 4 },
        { 'a', 9, 4 },
        { 'b', 11, 4 },
        { 'c', 0, 5 },
        { 'd', 2, 5 }
    };

    for (size_t i = 0; i < sizeof(noteMap)/sizeof(noteMap[0]); i++)
        if (noteMap[i].c == c)
            return noteFreq(noteMap[i].note, noteMap[i].octave);

    assert(0);
}

void parseNotes(ALBuffer &buffer, const char *notes, int rate)
{
    std::vector<short> data;
    while (*notes) {
        double freq = getNoteFreq(*notes++);
        double duration = getDuration(*notes++);
        double step = M_PI*2*freq/rate;
        int nsamples = duration*rate;
        for (int i = 0; i < nsamples; i++)
            data.push_back(20000*sin(i*step));
    }

    buffer.setData(AL_FORMAT_MONO16, &data[0], data.size()*2, rate);
}

int main()
{
    ALCdevice *dev = alcOpenDevice(NULL);
    assert(dev);
    ALCcontext *ctx = alcCreateContext(dev, NULL);
    assert(ctx);
    alcMakeContextCurrent(ctx);

    {
        ALBufferPtr buffer = new ALBuffer();
        //readOGG("/home/stepan/science.ogg", *buffer);

        const char music[] =
            "D4"             "D4b4a4g4"    "D2 4D4"    "D4b4a4g4"
            "e2 4e4"        "e4c4b4a4"    "f2 4d4"     "d4d4c4a4"
            "b2g4D4"       "D4b4a4g4"    "D2 4D4"    "D4b4a4g4"
            "e2 4e4"        "e4c4b4a4"    "d4d4d4d4" "e4d4c4a4"
            "g2g4 4"        "b4b4b2"       "b4b4b2"    "b4d4g4a8" "b2"
            "c4c4c4c8"    "c4b4b4b8b8" "b4a4a4b4" "a2d2"
            "b4b4b2"       "b4b4b2"       "b4d4g4a8" "b2 4"        "c4c4"
            "c4b4b4b8b8" "d4d4c4a4"    "g2";

        parseNotes(*buffer, music, 44100);

        ALSource source;
        source.setBuffer(buffer);
        source.play();

        while (source.getState() != AL_STOPPED)
            sleep(1);
    }

    alcMakeContextCurrent(NULL);
    alcDestroyContext(ctx);
    alcCloseDevice(dev);
    return 0;
}