eiifwhrn-game-engine-edition/FMOD/api/core/examples/dsp_custom.cpp

/*==============================================================================
Custom DSP Example
Copyright (c), Firelight Technologies Pty, Ltd 2004-2026.

This example shows how to add a user created DSP callback to process audio 
data. The read callback is executed at runtime, and can be added anywhere in
the DSP network.

For information on using FMOD example code in your own programs, visit
https://www.fmod.com/legal
==============================================================================*/
#include "fmod.hpp"
#include "common.h"

typedef struct 
{
    float *buffer;
    float volume_linear;
    int   length_samples;
    int   channels;
} mydsp_data_t;

FMOD_RESULT F_CALL myDSPCallback(FMOD_DSP_STATE *dsp_state, float *inbuffer, float *outbuffer, unsigned int length, int inchannels, int *outchannels) 
{
    mydsp_data_t *data = (mydsp_data_t *)dsp_state->plugindata;

    /*
        This loop assumes inchannels = outchannels, which it will be if the DSP is created with '0' 
        as the number of channels in FMOD_DSP_DESCRIPTION.  
        Specifying an actual channel count will mean you have to take care of any number of channels coming in,
        but outputting the number of channels specified. Generally it is best to keep the channel 
        count at 0 for maximum compatibility.
    */
    for (unsigned int samp = 0; samp < length; samp++) 
    { 
        /*
            Feel free to unroll this.
        */
        for (int chan = 0; chan < *outchannels; chan++)
        {
            /* 
                This DSP filter just halves the volume! 
                Input is modified, and sent to output.
            */
            data->buffer[(samp * *outchannels) + chan] = outbuffer[(samp * inchannels) + chan] = inbuffer[(samp * inchannels) + chan] * data->volume_linear;
        }
    }

    data->channels = inchannels;

    return FMOD_OK; 
} 

/*
    Callback called when DSP is created.   This implementation creates a structure which is attached to the dsp state's 'plugindata' member.
*/
FMOD_RESULT F_CALL myDSPCreateCallback(FMOD_DSP_STATE *dsp_state)
{
    unsigned int blocksize;
    FMOD_RESULT result;

    result = dsp_state->functions->getblocksize(dsp_state, &blocksize);
    ERRCHECK(result);

    mydsp_data_t *data = (mydsp_data_t *)calloc(sizeof(mydsp_data_t), 1);
    if (!data)
    {
        return FMOD_ERR_MEMORY;
    }
    dsp_state->plugindata = data;
    data->volume_linear = 1.0f;
    data->length_samples = blocksize;

    data->buffer = (float *)malloc(blocksize * 8 * sizeof(float));      // *8 = maximum size allowing room for 7.1.   Could ask dsp_state->functions->getspeakermode for the right speakermode to get real speaker count.
    if (!data->buffer)
    {
        return FMOD_ERR_MEMORY;
    }

    return FMOD_OK;
}

/*
    Callback called when DSP is destroyed.   The memory allocated in the create callback can be freed here.
*/
FMOD_RESULT F_CALL myDSPReleaseCallback(FMOD_DSP_STATE *dsp_state)
{
    if (dsp_state->plugindata)
    {
        mydsp_data_t *data = (mydsp_data_t *)dsp_state->plugindata;

        if (data->buffer)
        {
            free(data->buffer);
        }

        free(data);
    }

    return FMOD_OK;
}

/*
    Callback called when DSP::getParameterData is called.   This returns a pointer to the raw floating point PCM data.
    We have set up 'parameter 0' to be the data parameter, so it checks to make sure the passed in index is 0, and nothing else.
*/
FMOD_RESULT F_CALL myDSPGetParameterDataCallback(FMOD_DSP_STATE *dsp_state, int index, void **data, unsigned int *length, char *)
{
    if (index == 0)
    {
        unsigned int blocksize;
        FMOD_RESULT result;
        mydsp_data_t *mydata = (mydsp_data_t *)dsp_state->plugindata;

        result = dsp_state->functions->getblocksize(dsp_state, &blocksize);
        ERRCHECK(result);

        *data = (void *)mydata;
        *length = blocksize * 2 * sizeof(float);

        return FMOD_OK;
    }

    return FMOD_ERR_INVALID_PARAM;
}

/*
    Callback called when DSP::setParameterFloat is called.   This accepts a floating point 0 to 1 volume value, and stores it.
    We have set up 'parameter 1' to be the volume parameter, so it checks to make sure the passed in index is 1, and nothing else.
*/
FMOD_RESULT F_CALL myDSPSetParameterFloatCallback(FMOD_DSP_STATE *dsp_state, int index, float value)
{
    if (index == 1)
    {
        mydsp_data_t *mydata = (mydsp_data_t *)dsp_state->plugindata;

        mydata->volume_linear = value;

        return FMOD_OK;
    }

    return FMOD_ERR_INVALID_PARAM;
}

/*
    Callback called when DSP::getParameterFloat is called.   This returns a floating point 0 to 1 volume value.
    We have set up 'parameter 1' to be the volume parameter, so it checks to make sure the passed in index is 1, and nothing else.
    An alternate way of displaying the data is provided, as a string, so the main app can use it.
*/
FMOD_RESULT F_CALL myDSPGetParameterFloatCallback(FMOD_DSP_STATE *dsp_state, int index, float *value, char *valstr)
{
    if (index == 1)
    {
        mydsp_data_t *mydata = (mydsp_data_t *)dsp_state->plugindata;

        *value = mydata->volume_linear;
        if (valstr)
        {
            snprintf(valstr, FMOD_DSP_GETPARAM_VALUESTR_LENGTH, "%d", (int)((*value * 100.0f)+0.5f));
        }

        return FMOD_OK;
    }

    return FMOD_ERR_INVALID_PARAM;
}

int FMOD_Main()
{
    FMOD::System       *system;
    FMOD::Sound        *sound;
    FMOD::Channel      *channel;
    FMOD::DSP          *mydsp;
    FMOD::ChannelGroup *mastergroup;
    FMOD_RESULT         result;
    void               *extradriverdata = 0;

    Common_Init(&extradriverdata);

    /*
        Create a System object and initialize.
    */
    result = FMOD::System_Create(&system);
    ERRCHECK(result);

    result = system->init(32, FMOD_INIT_NORMAL, extradriverdata);
    ERRCHECK(result);

    result = system->createSound(Common_MediaPath("stereo.ogg"), FMOD_LOOP_NORMAL, 0, &sound);
    ERRCHECK(result);

    result = system->playSound(sound, 0, false, &channel);
    ERRCHECK(result);

    /*
        Create the DSP effect.
    */  
    { 
        FMOD_DSP_DESCRIPTION dspdesc; 
        memset(&dspdesc, 0, sizeof(dspdesc));
        FMOD_DSP_PARAMETER_DESC wavedata_desc;
        FMOD_DSP_PARAMETER_DESC volume_desc;
        FMOD_DSP_PARAMETER_DESC *paramdesc[2] = 
        {
            &wavedata_desc,
            &volume_desc
        };

        FMOD_DSP_INIT_PARAMDESC_DATA(wavedata_desc, "wave data", "", "wave data", FMOD_DSP_PARAMETER_DATA_TYPE_USER);
        FMOD_DSP_INIT_PARAMDESC_FLOAT(volume_desc, "volume", "%", "linear volume in percent", 0, 1, 1);

        strncpy(dspdesc.name, "My first DSP unit", sizeof(dspdesc.name));
        dspdesc.version             = 0x00010000;
        dspdesc.numinputbuffers     = 1;
        dspdesc.numoutputbuffers    = 1;
        dspdesc.read                = myDSPCallback; 
        dspdesc.create              = myDSPCreateCallback;
        dspdesc.release             = myDSPReleaseCallback;
        dspdesc.getparameterdata    = myDSPGetParameterDataCallback;
        dspdesc.setparameterfloat   = myDSPSetParameterFloatCallback;
        dspdesc.getparameterfloat   = myDSPGetParameterFloatCallback;
        dspdesc.numparameters       = 2;
        dspdesc.paramdesc           = paramdesc;

        result = system->createDSP(&dspdesc, &mydsp); 
        ERRCHECK(result); 
    } 

    result = system->getMasterChannelGroup(&mastergroup);
    ERRCHECK(result);

    result = mastergroup->addDSP(0, mydsp);
    ERRCHECK(result);

    /*
        Main loop.
    */
    do
    {
        bool bypass;

        Common_Update();

        result = mydsp->getBypass(&bypass);
        ERRCHECK(result);

        if (Common_BtnPress(BTN_ACTION1))
        {
            bypass = !bypass;
            
            result = mydsp->setBypass(bypass);
            ERRCHECK(result);
        }        
        if (Common_BtnPress(BTN_ACTION2))
        {
            float vol;

            result = mydsp->getParameterFloat(1, &vol, 0, 0);
            ERRCHECK(result);

            if (vol > 0.0f)
            {
                vol -= 0.1f;
            }

            result = mydsp->setParameterFloat(1, vol);
            ERRCHECK(result);
        }
        if (Common_BtnPress(BTN_ACTION3))
        {
            float vol;

            result = mydsp->getParameterFloat(1, &vol, 0, 0);
            ERRCHECK(result);

            if (vol < 1.0f)
            {
                vol += 0.1f;
            }

            result = mydsp->setParameterFloat(1, vol);
            ERRCHECK(result);
        }

        result = system->update();
        ERRCHECK(result);

        {
            char                     volstr[32] = { 0 };
            FMOD_DSP_PARAMETER_DESC *desc;
            mydsp_data_t            *data;

            result = mydsp->getParameterInfo(1, &desc);
            ERRCHECK(result);
            result = mydsp->getParameterFloat(1, 0, volstr, 32);
            ERRCHECK(result);
            result = mydsp->getParameterData(0, (void **)&data, 0, 0, 0);
            ERRCHECK(result);

            Common_Draw("==================================================");
            Common_Draw("Custom DSP Example.");
            Common_Draw("Copyright (c) Firelight Technologies 2004-2026.");
            Common_Draw("==================================================");
            Common_Draw("");
            Common_Draw("Press %s to toggle filter bypass", Common_BtnStr(BTN_ACTION1));
            Common_Draw("Press %s to decrease volume 10%%", Common_BtnStr(BTN_ACTION2));
            Common_Draw("Press %s to increase volume 10%%", Common_BtnStr(BTN_ACTION3));
            Common_Draw("Press %s to quit", Common_BtnStr(BTN_QUIT));
            Common_Draw("");
            Common_Draw("Filter is %s", bypass ? "inactive" : "active");
            Common_Draw("Volume is %s%s", volstr, desc->label);

            if (data->channels)
            {
                char display[80] = { 0 };
                int channel;

                for (channel = 0; channel < data->channels; channel++)
                {
                    int count,level;
                    float max = 0;

                    for (count = 0; count < data->length_samples; count++)
                    {
                        if (fabsf(data->buffer[(count * data->channels) + channel]) > max)
                        {
                            max = fabsf(data->buffer[(count * data->channels) + channel]);
                        }
                    }
                    level = (int)(max * 40.0f);
                    
                    snprintf(display, sizeof(display), "%2d ", channel);
                    for (count = 0; count < level; count++) display[count + 3] = '=';

                    Common_Draw(display);
                }
            }
        }

        Common_Sleep(50);
    } while (!Common_BtnPress(BTN_QUIT));

    /*
        Shut down
    */
    result = sound->release();
    ERRCHECK(result);

    result = mastergroup->removeDSP(mydsp);
    ERRCHECK(result);
    result = mydsp->release();
    ERRCHECK(result);

    result = system->close();
    ERRCHECK(result);
    result = system->release();
    ERRCHECK(result);

    Common_Close();

    return 0;
}