OpenSceneGraph/examples/osgmovie/osgmovie.cpp

/* OpenSceneGraph example, osgmovie.
*
*  Permission is hereby granted, free of charge, to any person obtaining a copy
*  of this software and associated documentation files (the "Software"), to deal
*  in the Software without restriction, including without limitation the rights
*  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
*  copies of the Software, and to permit persons to whom the Software is
*  furnished to do so, subject to the following conditions:
*
*  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
*  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
*  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
*  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
*  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
*  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
*  THE SOFTWARE.
*/

#include <osgViewer/Viewer>
#include <osgViewer/ViewerEventHandlers>

#include <osgDB/ReadFile>

#include <osg/Geode>
#include <osg/Geometry>
#include <osg/StateSet>
#include <osg/Material>
#include <osg/Texture2D>
#include <osg/TextureRectangle>
#include <osg/TextureCubeMap>
#include <osg/TexMat>
#include <osg/CullFace>
#include <osg/ImageStream>
#include <osg/io_utils>

#include <osgGA/TrackballManipulator>
#include <osgGA/StateSetManipulator>
#include <osgGA/EventVisitor>

#include <iostream>

class MovieEventHandler : public osgGA::GUIEventHandler
{
public:

    MovieEventHandler():_trackMouse(false) {}

    void setMouseTracking(bool track) { _trackMouse = track; }
    bool getMouseTracking() const { return _trackMouse; }

    void set(osg::Node* node);

    virtual bool handle(const osgGA::GUIEventAdapter& ea,osgGA::GUIActionAdapter& aa, osg::Object*, osg::NodeVisitor* nv);

    virtual void getUsage(osg::ApplicationUsage& usage) const;

    typedef std::vector< osg::observer_ptr<osg::ImageStream> > ImageStreamList;

protected:

    virtual ~MovieEventHandler() {}

    class FindImageStreamsVisitor : public osg::NodeVisitor
    {
    public:
        FindImageStreamsVisitor(ImageStreamList& imageStreamList):
            _imageStreamList(imageStreamList) {}

        virtual void apply(osg::Geode& geode)
        {
            apply(geode.getStateSet());

            for(unsigned int i=0;i<geode.getNumDrawables();++i)
            {
                apply(geode.getDrawable(i)->getStateSet());
            }

            traverse(geode);
        }

        virtual void apply(osg::Node& node)
        {
            apply(node.getStateSet());
            traverse(node);
        }

        inline void apply(osg::StateSet* stateset)
        {
            if (!stateset) return;

            osg::StateAttribute* attr = stateset->getTextureAttribute(0,osg::StateAttribute::TEXTURE);
            if (attr)
            {
                osg::Texture2D* texture2D = dynamic_cast<osg::Texture2D*>(attr);
                if (texture2D) apply(dynamic_cast<osg::ImageStream*>(texture2D->getImage()));

                osg::TextureRectangle* textureRec = dynamic_cast<osg::TextureRectangle*>(attr);
                if (textureRec) apply(dynamic_cast<osg::ImageStream*>(textureRec->getImage()));
            }
        }

        inline void apply(osg::ImageStream* imagestream)
        {
            if (imagestream)
            {
                _imageStreamList.push_back(imagestream);
            }
        }

        ImageStreamList& _imageStreamList;

    protected:

        FindImageStreamsVisitor& operator = (const FindImageStreamsVisitor&) { return *this; }

    };


    bool            _trackMouse;
    ImageStreamList _imageStreamList;
    unsigned int    _seekIncr;

};



void MovieEventHandler::set(osg::Node* node)
{
    _imageStreamList.clear();
    if (node)
    {
        FindImageStreamsVisitor fisv(_imageStreamList);
        node->accept(fisv);
    }
}


bool MovieEventHandler::handle(const osgGA::GUIEventAdapter& ea,osgGA::GUIActionAdapter& aa, osg::Object*, osg::NodeVisitor* nv)
{
    switch(ea.getEventType())
    {
        case(osgGA::GUIEventAdapter::MOVE):
        case(osgGA::GUIEventAdapter::PUSH):
        case(osgGA::GUIEventAdapter::RELEASE):
        {
            if (_trackMouse)
            {
                osgViewer::View* view = dynamic_cast<osgViewer::View*>(&aa);
                osgUtil::LineSegmentIntersector::Intersections intersections;
                bool foundIntersection = view==0 ? false :
                    (nv==0 ? view->computeIntersections(ea, intersections) :
                             view->computeIntersections(ea, nv->getNodePath(), intersections));

                if (foundIntersection)
                {

                    // use the nearest intersection
                    const osgUtil::LineSegmentIntersector::Intersection& intersection = *(intersections.begin());
                    osg::Drawable* drawable = intersection.drawable.get();
                    osg::Geometry* geometry = drawable ? drawable->asGeometry() : 0;
                    osg::Vec3Array* vertices = geometry ? dynamic_cast<osg::Vec3Array*>(geometry->getVertexArray()) : 0;
                    if (vertices)
                    {
                        // get the vertex indices.
                        const osgUtil::LineSegmentIntersector::Intersection::IndexList& indices = intersection.indexList;
                        const osgUtil::LineSegmentIntersector::Intersection::RatioList& ratios = intersection.ratioList;

                        if (indices.size()==3 && ratios.size()==3)
                        {
                            unsigned int i1 = indices[0];
                            unsigned int i2 = indices[1];
                            unsigned int i3 = indices[2];

                            float r1 = ratios[0];
                            float r2 = ratios[1];
                            float r3 = ratios[2];

                            osg::Array* texcoords = (geometry->getNumTexCoordArrays()>0) ? geometry->getTexCoordArray(0) : 0;
                            osg::Vec2Array* texcoords_Vec2Array = dynamic_cast<osg::Vec2Array*>(texcoords);
                            if (texcoords_Vec2Array)
                            {
                                // we have tex coord array so now we can compute the final tex coord at the point of intersection.
                                osg::Vec2 tc1 = (*texcoords_Vec2Array)[i1];
                                osg::Vec2 tc2 = (*texcoords_Vec2Array)[i2];
                                osg::Vec2 tc3 = (*texcoords_Vec2Array)[i3];
                                osg::Vec2 tc = tc1*r1 + tc2*r2 + tc3*r3;

                                osg::notify(osg::NOTICE)<<"We hit tex coords "<<tc<<std::endl;

                            }
                        }
                        else
                        {
                            osg::notify(osg::NOTICE)<<"Intersection has insufficient indices to work with";
                        }

                    }
                }
                else
                {
                    osg::notify(osg::NOTICE)<<"No intersection"<<std::endl;
                }
            }
            break;
        }
        case(osgGA::GUIEventAdapter::KEYDOWN):
        {
            if (ea.getKey()=='p')
            {
                for(ImageStreamList::iterator itr=_imageStreamList.begin();
                    itr!=_imageStreamList.end();
                    ++itr)
                {
                    osg::ImageStream::StreamStatus playToggle = (*itr)->getStatus();
                    if (playToggle != osg::ImageStream::PLAYING)
                    {
                        std::cout<< (*itr).get() << " Play"<<std::endl;
                        (*itr)->play();
                    }
                    else
                    {
                        // playing, so pause
                        std::cout<< (*itr).get() << " Pause"<<std::endl;
                        (*itr)->pause();
                    }
                }
                return true;
            }
            else if (ea.getKey()=='r')
            {
                for(ImageStreamList::iterator itr=_imageStreamList.begin();
                    itr!=_imageStreamList.end();
                    ++itr)
                {
                    std::cout<< (*itr).get() << " Restart"<<std::endl;
                    (*itr)->rewind();
                    (*itr)->play();
                }
                return true;
            }
            else if (ea.getKey()=='>')
            {
                for(ImageStreamList::iterator itr=_imageStreamList.begin();
                    itr!=_imageStreamList.end();
                    ++itr)
                {
                    std::cout<<"Seeking"<<std::endl;
                    if(_seekIncr > 3) _seekIncr = 0;
                    double length = (*itr)->getLength();
                    double t_pos = (length/4.0f)*_seekIncr;
                    //(*itr)->rewind();
                    (*itr)->seek(t_pos);
                    (*itr)->play();
                    _seekIncr++;
                }
                return true;
            }
            else if (ea.getKey()=='L')
            {
                for(ImageStreamList::iterator itr=_imageStreamList.begin();
                    itr!=_imageStreamList.end();
                    ++itr)
                {
                    if ( (*itr)->getLoopingMode() == osg::ImageStream::LOOPING)
                    {
                        std::cout<< (*itr).get() << " Toggle Looping Off"<<std::endl;
                        (*itr)->setLoopingMode( osg::ImageStream::NO_LOOPING );
                    }
                    else
                    {
                        std::cout<< (*itr).get() << " Toggle Looping On"<<std::endl;
                        (*itr)->setLoopingMode( osg::ImageStream::LOOPING );
                    }
                }
                return true;
            }
            else if (ea.getKey()=='+')
            {
                for(ImageStreamList::iterator itr=_imageStreamList.begin();
                    itr!=_imageStreamList.end();
                    ++itr)
                {
                    double tm = (*itr)->getTimeMultiplier();
                    tm += 0.1;
                    (*itr)->setTimeMultiplier(tm);
                    std::cout << (*itr).get() << " Increase speed rate "<< (*itr)->getTimeMultiplier() << std::endl;
                }
                return true;
            }
            else if (ea.getKey()=='-')
            {
                for(ImageStreamList::iterator itr=_imageStreamList.begin();
                    itr!=_imageStreamList.end();
                    ++itr)
                {
                    double tm = (*itr)->getTimeMultiplier();
                    tm -= 0.1;
                    (*itr)->setTimeMultiplier(tm);
                    std::cout << (*itr).get() << " Decrease speed rate "<< (*itr)->getTimeMultiplier() << std::endl;
                }
                return true;
            }
            else if (ea.getKey()=='o')
            {
                for(ImageStreamList::iterator itr=_imageStreamList.begin();
                    itr!=_imageStreamList.end();
                    ++itr)
                {
                    std::cout<< (*itr).get() << " Frame rate  "<< (*itr)->getFrameRate() <<std::endl;
                }
                return true;
            }
            return false;
        }

        default:
            return false;
    }
    return false;
}

void MovieEventHandler::getUsage(osg::ApplicationUsage& usage) const
{
    usage.addKeyboardMouseBinding("p","Play/Pause movie");
    usage.addKeyboardMouseBinding("r","Restart movie");
    usage.addKeyboardMouseBinding("l","Toggle looping of movie");
    usage.addKeyboardMouseBinding("+","Increase speed of movie");
    usage.addKeyboardMouseBinding("-","Decrease speed of movie");
    usage.addKeyboardMouseBinding("o","Display frame rate of movie");
    usage.addKeyboardMouseBinding(">","Advance the movie using seek");
}


osg::Geometry* myCreateTexturedQuadGeometry(const osg::Vec3& pos,float width,float height, osg::Image* image, bool useTextureRectangle, bool xyPlane, bool option_flip)
{
    bool flip = image->getOrigin()==osg::Image::TOP_LEFT;
    if (option_flip) flip = !flip;

    if (useTextureRectangle)
    {
        osg::Geometry* pictureQuad = osg::createTexturedQuadGeometry(pos,
                                           osg::Vec3(width,0.0f,0.0f),
                                           xyPlane ? osg::Vec3(0.0f,height,0.0f) : osg::Vec3(0.0f,0.0f,height),
                                           0.0f, flip ? image->t() : 0.0, image->s(), flip ? 0.0 : image->t());

        osg::TextureRectangle* texture = new osg::TextureRectangle(image);
        texture->setWrap(osg::Texture::WRAP_S, osg::Texture::CLAMP_TO_EDGE);
        texture->setWrap(osg::Texture::WRAP_T, osg::Texture::CLAMP_TO_EDGE);


        pictureQuad->getOrCreateStateSet()->setTextureAttributeAndModes(0,
                                                                        texture,
                                                                        osg::StateAttribute::ON);

        return pictureQuad;
    }
    else
    {
        osg::Geometry* pictureQuad = osg::createTexturedQuadGeometry(pos,
                                           osg::Vec3(width,0.0f,0.0f),
                                           xyPlane ? osg::Vec3(0.0f,height,0.0f) : osg::Vec3(0.0f,0.0f,height),
                                           0.0f, flip ? 1.0f : 0.0f , 1.0f, flip ? 0.0f : 1.0f);

        osg::Texture2D* texture = new osg::Texture2D(image);
        texture->setResizeNonPowerOfTwoHint(false);
        texture->setFilter(osg::Texture::MIN_FILTER,osg::Texture::LINEAR);
        texture->setWrap(osg::Texture::WRAP_S, osg::Texture::CLAMP_TO_EDGE);
        texture->setWrap(osg::Texture::WRAP_T, osg::Texture::CLAMP_TO_EDGE);


        pictureQuad->getOrCreateStateSet()->setTextureAttributeAndModes(0,
                    texture,
                    osg::StateAttribute::ON);

        return pictureQuad;
    }
}

#if USE_SDL || USE_SDL2

class SDLAudioSink : public osg::AudioSink
{
    public:

        SDLAudioSink(osg::AudioStream* audioStream):
            _started(false),
            _paused(false),
            _audioStream(audioStream) {}

        ~SDLAudioSink();

        virtual void play();
        virtual void pause();
        virtual void stop();

        virtual bool playing() const { return _started && !_paused; }


        bool                                _started;
        bool                                _paused;
        osg::observer_ptr<osg::AudioStream> _audioStream;
};

#endif

int main(int argc, char** argv)
{
    // use an ArgumentParser object to manage the program arguments.
    osg::ArgumentParser arguments(&argc,argv);

    // set up the usage document, in case we need to print out how to use this program.
    arguments.getApplicationUsage()->setApplicationName(arguments.getApplicationName());
    arguments.getApplicationUsage()->setDescription(arguments.getApplicationName()+" example demonstrates the use of ImageStream for rendering movies as textures.");
    arguments.getApplicationUsage()->setCommandLineUsage(arguments.getApplicationName()+" [options] filename ...");
    arguments.getApplicationUsage()->addCommandLineOption("-h or --help","Display this information");
    arguments.getApplicationUsage()->addCommandLineOption("--texture2D","Use Texture2D rather than TextureRectangle.");
    arguments.getApplicationUsage()->addCommandLineOption("--shader","Use shaders to post process the video.");
    arguments.getApplicationUsage()->addCommandLineOption("--interactive","Use camera manipulator to allow movement around movie.");
    arguments.getApplicationUsage()->addCommandLineOption("--flip","Flip the movie so top becomes bottom.");
#if defined(WIN32) || defined(__APPLE__)
    arguments.getApplicationUsage()->addCommandLineOption("--devices","Print the Video input capability via QuickTime and exit.");
#endif

    bool useTextureRectangle = true;
    bool useShader = false;

    // construct the viewer.
    osgViewer::Viewer viewer(arguments);

    if (arguments.argc()<=1)
    {
        arguments.getApplicationUsage()->write(std::cout,osg::ApplicationUsage::COMMAND_LINE_OPTION);
        return 1;
    }

#if defined(WIN32) || defined(__APPLE__)
    // if user requests devices video capability.
    if (arguments.read("-devices") || arguments.read("--devices"))
    {
        // Force load QuickTime plugin, probe video capability, exit
        osgDB::readRefImageFile("devices.live");
        return 1;
    }
#endif

    while (arguments.read("--texture2D")) useTextureRectangle=false;
    while (arguments.read("--shader")) useShader=true;

    bool mouseTracking = false;
    while (arguments.read("--mouse")) mouseTracking=true;


    // if user request help write it out to cout.
    if (arguments.read("-h") || arguments.read("--help"))
    {
        arguments.getApplicationUsage()->write(std::cout);
        return 1;
    }

    bool fullscreen = !arguments.read("--interactive");
    bool flip = arguments.read("--flip");

    osg::ref_ptr<osg::Geode> geode = new osg::Geode;

    osg::StateSet* stateset = geode->getOrCreateStateSet();
    stateset->setMode(GL_LIGHTING,osg::StateAttribute::OFF);

    if (useShader)
    {
        //useTextureRectangle = false;

        static const char *shaderSourceTextureVertex = {
            "#ifdef GL_ES\n"
            "    precision highp float;\n"
            "    precision highp int;\n"
            "#endif\n"
            "varying vec4 texcoord;\n"
            "void main(void)\n"
            "{\n"
            "    texcoord = gl_MultiTexCoord0; \n"
            "    gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
            "}\n"
        };

        static const char *shaderSourceTextureRec = {
            "#ifdef GL_ES\n"
            "    precision highp float;\n"
            "    precision highp int;\n"
            "#endif\n"
            "uniform vec4 cutoff_color;\n"
            "uniform samplerRect movie_texture;\n"
            "varying vec4 texcoord;\n"
            "void main(void)\n"
            "{\n"
            "    vec4 texture_color = textureRect(movie_texture, texcoord.st); \n"
            "    if (all(lessThanEqual(texture_color,cutoff_color))) discard; \n"
            "    gl_FragColor = texture_color;\n"
            "}\n"
        };

        static const char *shaderSourceTexture2D = {
            "#ifdef GL_ES\n"
            "    precision highp float;\n"
            "    precision highp int;\n"
            "#endif\n"
            "uniform vec4 cutoff_color;\n"
            "uniform sampler2D movie_texture;\n"
            "varying vec4 texcoord;\n"
            "void main(void)\n"
            "{\n"
            "    vec4 texture_color = texture2D(movie_texture, texcoord.st); \n"
            "    if (all(lessThanEqual(texture_color,cutoff_color))) discard; \n"
            "    gl_FragColor = texture_color;\n"
            "}\n"
        };

        osg::Program* program = new osg::Program;


        program->addShader(new osg::Shader(osg::Shader::VERTEX, shaderSourceTextureVertex));

        program->addShader(new osg::Shader(osg::Shader::FRAGMENT,
                                           useTextureRectangle ? shaderSourceTextureRec : shaderSourceTexture2D));

        stateset->addUniform(new osg::Uniform("cutoff_color",osg::Vec4(0.1f,0.1f,0.1f,1.0f)));
        stateset->addUniform(new osg::Uniform("movie_texture",0));

        stateset->setAttribute(program);

    }

    osg::Vec3 pos(0.0f,0.0f,0.0f);
    osg::Vec3 topleft = pos;
    osg::Vec3 bottomright = pos;

    bool xyPlane = fullscreen;

    bool useAudioSink = false;
    while(arguments.read("--audio")) { useAudioSink = true; }

#if USE_SDL || USE_SDL2
    unsigned int numAudioStreamsEnabled = 0;
#endif

    for(int i=1;i<arguments.argc();++i)
    {
        if (arguments.isString(i))
        {
            osg::ref_ptr<osg::Image> image = osgDB::readRefImageFile(arguments[i]);
            osg::ImageStream* imagestream = dynamic_cast<osg::ImageStream*>(image.get());
            if (imagestream)
            {
                osg::ImageStream::AudioStreams& audioStreams = imagestream->getAudioStreams();
                if (useAudioSink && !audioStreams.empty())
                {
                    osg::AudioStream* audioStream = audioStreams[0].get();
                    osg::notify(osg::NOTICE)<<"AudioStream read ["<<audioStream->getName()<<"]"<<std::endl;
#if USE_SDL || USE_SDL2
                    if (numAudioStreamsEnabled==0)
                    {
                        audioStream->setAudioSink(new SDLAudioSink(audioStream));

                        ++numAudioStreamsEnabled;
                    }
#endif
                }


                imagestream->play();
            }

            if (image)
            {
                osg::notify(osg::NOTICE)<<"image->s()"<<image->s()<<" image-t()="<<image->t()<<" aspectRatio="<<image->getPixelAspectRatio()<<std::endl;

                float width = image->s() * image->getPixelAspectRatio();
                float height = image->t();

                osg::ref_ptr<osg::Drawable> drawable = myCreateTexturedQuadGeometry(pos, width, height, image.get(), useTextureRectangle, xyPlane, flip);

                if (image->isImageTranslucent())
                {
                    osg::notify(osg::NOTICE)<<"Transparent movie, enabling blending."<<std::endl;

                    drawable->getOrCreateStateSet()->setMode(GL_BLEND, osg::StateAttribute::ON);
                    drawable->getOrCreateStateSet()->setRenderingHint(osg::StateSet::TRANSPARENT_BIN);
                }

                geode->addDrawable(drawable.get());

                bottomright = pos + osg::Vec3(width,height,0.0f);

                if (xyPlane) pos.y() += height*1.05f;
                else pos.z() += height*1.05f;
            }
            else
            {
                std::cout<<"Unable to read file "<<arguments[i]<<std::endl;
            }
        }
    }

    // set the scene to render
    viewer.setSceneData(geode.get());

    if (viewer.getSceneData()==0)
    {
        arguments.getApplicationUsage()->write(std::cout);
        return 1;
    }

    // pass the model to the MovieEventHandler so it can pick out ImageStream's to manipulate.
    MovieEventHandler* meh = new MovieEventHandler();
    meh->setMouseTracking( mouseTracking );
    meh->set( viewer.getSceneData() );
    viewer.addEventHandler( meh );

    viewer.addEventHandler( new osgViewer::StatsHandler );
    viewer.addEventHandler( new osgGA::StateSetManipulator( viewer.getCamera()->getOrCreateStateSet() ) );
    viewer.addEventHandler( new osgViewer::WindowSizeHandler );

    // add the record camera path handler
    viewer.addEventHandler(new osgViewer::RecordCameraPathHandler);

    // report any errors if they have occurred when parsing the program arguments.
    if (arguments.errors())
    {
        arguments.writeErrorMessages(std::cout);
        return 1;
    }

    if (fullscreen)
    {
        viewer.realize();

        viewer.getCamera()->setClearColor(osg::Vec4(0.0f,0.0f,0.0f,1.0f));

        float screenAspectRatio = 1280.0f/1024.0f;

        osg::GraphicsContext::WindowingSystemInterface* wsi = osg::GraphicsContext::getWindowingSystemInterface();
        if (wsi)
        {
            unsigned int width, height;
            osg::GraphicsContext::ScreenIdentifier main_screen_id;

            main_screen_id.readDISPLAY();
            main_screen_id.setUndefinedScreenDetailsToDefaultScreen();
            wsi->getScreenResolution(main_screen_id, width, height);

            screenAspectRatio = float(width) / float(height);
        }

        float modelAspectRatio = (bottomright.x()-topleft.x())/(bottomright.y()-topleft.y());

        viewer.getCamera()->setViewMatrix(osg::Matrix::identity());


        osg::Vec3 center = (bottomright + topleft)*0.5f;
        osg::Vec3 dx(bottomright.x()-center.x(), 0.0f, 0.0f);
        osg::Vec3 dy(0.0f, topleft.y()-center.y(), 0.0f);

        float ratio = modelAspectRatio/screenAspectRatio;

        if (ratio>1.0f)
        {
            // use model width as the control on model size.
            bottomright = center + dx - dy * ratio;
            topleft = center - dx + dy * ratio;
        }
        else
        {
            // use model height as the control on model size.
            bottomright = center + dx / ratio - dy;
            topleft = center - dx / ratio + dy;
        }

        viewer.getCamera()->setProjectionMatrixAsOrtho2D(topleft.x(),bottomright.x(),topleft.y(),bottomright.y());

        while(!viewer.done())
        {
            viewer.frame();
        }
        return 0;
    }
    else
    {
        // create the windows and run the threads.
        return viewer.run();
    }
}

#if USE_SDL || USE_SDL2

#include "SDL.h"

static void soundReadCallback(void * user_data, uint8_t * data, int datalen)
{
    SDLAudioSink * sink = reinterpret_cast<SDLAudioSink*>(user_data);
    osg::ref_ptr<osg::AudioStream> as = sink->_audioStream.get();
    if (as.valid())
    {
        as->consumeAudioBuffer(data, datalen);
    }
}

SDLAudioSink::~SDLAudioSink()
{
    stop();
}

void SDLAudioSink::play()
{
    if (_started)
    {
        if (_paused)
        {
            SDL_PauseAudio(0);
            _paused = false;
        }
        return;
    }

    _started = true;
    _paused = false;

    osg::notify(osg::NOTICE)<<"SDLAudioSink()::startPlaying()"<<std::endl;

    osg::notify(osg::NOTICE)<<"  audioFrequency()="<<_audioStream->audioFrequency()<<std::endl;
    osg::notify(osg::NOTICE)<<"  audioNbChannels()="<<_audioStream->audioNbChannels()<<std::endl;
    osg::notify(osg::NOTICE)<<"  audioSampleFormat()="<<_audioStream->audioSampleFormat()<<std::endl;



    SDL_AudioSpec specs;
    SDL_AudioSpec wanted_specs;

    wanted_specs.freq = _audioStream->audioFrequency();
    wanted_specs.channels = _audioStream->audioNbChannels();
    wanted_specs.silence = 0;
    wanted_specs.samples = 1024;
    wanted_specs.callback = soundReadCallback;
    wanted_specs.userdata = this;
    wanted_specs.format = 0;

#if SDL_MAJOR_VERSION>=2
    switch(_audioStream->audioSampleFormat())
    {
        case(osg::AudioStream::SAMPLE_FORMAT_U8):  { wanted_specs.format = AUDIO_U8; OSG_NOTICE<<"    SampleFormat  = SAMPLE_FORMAT_U8"<<std::endl;  break;}
        case(osg::AudioStream::SAMPLE_FORMAT_S16): { wanted_specs.format = AUDIO_S16SYS; OSG_NOTICE<<"    SampleFormat  = SAMPLE_FORMAT_S16"<<std::endl; break; }
        case(osg::AudioStream::SAMPLE_FORMAT_S24): { OSG_NOTICE<<"    SampleFormat  = SAMPLE_FORMAT_S24 NOT Supported by SDL."<<std::endl; break; }
        case(osg::AudioStream::SAMPLE_FORMAT_S32): { wanted_specs.format = AUDIO_S32SYS; OSG_NOTICE<<"    SampleFormat  = SAMPLE_FORMAT_S32"<<std::endl; break; }
        case(osg::AudioStream::SAMPLE_FORMAT_F32): { wanted_specs.format = AUDIO_F32SYS; OSG_NOTICE<<"    SampleFormat  = SAMPLE_FORMAT_F32"<<std::endl; break; }
    }
#else
    switch(_audioStream->audioSampleFormat())
    {
        case(osg::AudioStream::SAMPLE_FORMAT_U8):  { wanted_specs.format = AUDIO_U8; OSG_NOTICE<<"    SampleFormat  = SAMPLE_FORMAT_U8"<<std::endl;  break;}
        case(osg::AudioStream::SAMPLE_FORMAT_S16): { wanted_specs.format = AUDIO_S16SYS; OSG_NOTICE<<"    SampleFormat  = SAMPLE_FORMAT_S16"<<std::endl; break; }
        case(osg::AudioStream::SAMPLE_FORMAT_S24): { OSG_NOTICE<<"    SampleFormat  = SAMPLE_FORMAT_S24 NOT Supported by SDL1.x."<<std::endl; break; }
        case(osg::AudioStream::SAMPLE_FORMAT_S32): { OSG_NOTICE<<"    SampleFormat  = SAMPLE_FORMAT_S32 NOT Supported by SDL1.x"<<std::endl; break; }
        case(osg::AudioStream::SAMPLE_FORMAT_F32): { OSG_NOTICE<<"    SampleFormat  = SAMPLE_FORMAT_F32 NOT Supported by SDL1.x"<<std::endl; break; }
    }
#endif

    if (wanted_specs.format!=0)
    {

        if (SDL_OpenAudio(&wanted_specs, &specs) < 0)
            throw "SDL_OpenAudio() failed (" + std::string(SDL_GetError()) + ")";

        SDL_PauseAudio(0);
    }
    else
    {
        throw "SDL_OpenAudio() does not support audio format";
    }
}

void SDLAudioSink::pause()
{
    if (_started)
    {
        SDL_PauseAudio(1);
        _paused = true;
    }
}

void SDLAudioSink::stop()
{
    if (_started)
    {
        if (!_paused) SDL_PauseAudio(1);
        SDL_CloseAudio();

        osg::notify(osg::NOTICE)<<"~SDLAudioSink() destructor, but still playing"<<std::endl;
    }
}

#endif