raspi-synth/src/synthapp.cpp

#include <cstdlib>
#include <cmath>
#include <iostream>

#include <porttime.h>

#include "synthapp.h"
#include "synthframe.h"

using namespace std;

// PortAudio callback for audio I/O
static int paCallback(
        const void *inputBuffer,
        void *outputBuffer,
        unsigned long framesPerBuffer,
        const PaStreamCallbackTimeInfo* timeInfo,
        PaStreamCallbackFlags statusFlags,
        void *userData ) {
    
    Synth *state = (Synth*) userData;
    float *out = (float*)outputBuffer;

    for(int i = 0; i < framesPerBuffer; i++) {
        float value = 0;
        
        *out++ = value;
        *out++ = value;
    }

    return 0;
}

// PortTimer callback for MIDI I/O
static void ptCallback(PtTimestamp timestamp, void* userData) {
    SynthApp* app = (SynthApp*) userData;
    PmEvent events[8];
    int numEvents = Pm_Read(app->pmStream, events, 8);
    for(int i = 0; i < numEvents; ++i) {
        PmMessage msg = events[i].message;

        int type = (msg >> 4) & 0xF;
        int ch = msg & 0xF;
        
        if(type == 0x8 || (type == 0x9 && Pm_MessageData2(msg) == 0)) { // Note Off
        
        } else if(type == 0x9) { // Note On
            int note = Pm_MessageData1(msg);
            int vel = Pm_MessageData2(msg);

        } else if(type == 0xB) { // Controller Message
            int cc = Pm_MessageData1(msg);
            int val = Pm_MessageData2(msg);

            if(cc == 1 || cc == 74) { // Sound Controller 5: Brightness

            }
        }

        cout << "MIDI:";
        for(int j = 0; j < 24; j += 8) {
            cout << " " << hex << ((msg >> j) & 0xFF);
        }
        cout << endl;
    }
}

void handlePMError(PmError err) {
    Pt_Stop();
    Pa_Terminate();
    Pm_Terminate();
    cerr << "PortMidi error" << endl;
    cerr << "Error number: " << err << endl;
    cerr << "Error message: " << Pm_GetErrorText(err) << endl;
    exit(err);
}

void handlePAError(PaError err) {
    Pt_Stop();
    Pa_Terminate();
    Pm_Terminate();
    cerr << "PortAudio error" << endl;
    cerr << "Error number: " << err << endl;
    cerr << "Error message: " << Pa_GetErrorText(err) << endl;
    exit(err);
}

bool SynthApp::OnInit() {
    // Initialise PortMIDI and PortAudio libraries
    PmError pmErr = Pm_Initialize();
    if(pmErr != pmNoError) {
        handlePMError(pmErr);
    }
    PaError paErr = Pa_Initialize();
    if(paErr != paNoError) {
        handlePAError(paErr);
    }

    int pmDeviceCount = Pm_CountDevices();
    cout << "Select MIDI input device:" << endl;
    for(int i = 0; i < pmDeviceCount; ++i) {
        const PmDeviceInfo* deviceInfo = Pm_GetDeviceInfo(i);
        if(!deviceInfo->input) {
            continue;
        }
        cout << i << ". " << deviceInfo->name << endl;
    }
    int pmDeviceIndex;
    for(;;) { // loop for input until valid choice is made
        string input;
        getline(cin, input);
        try {
            pmDeviceIndex = stoi(input);
            if(     pmDeviceIndex >= 0 &&
                    pmDeviceIndex < pmDeviceCount &&
                    Pm_GetDeviceInfo(pmDeviceIndex)->input) {
                break;
            }
        } catch(...) { } // stoi() throws an exeption for invalid integers
        cout << "Invalid selection" << endl;   
    }

    PaHostApiIndex paDeviceCount = Pa_GetDeviceCount();
    cout << "Select audio output device:" << endl;
    for(int i = 0; i < paDeviceCount; ++i) {
        const PaDeviceInfo* deviceInfo = Pa_GetDeviceInfo(i);
        if(deviceInfo->maxOutputChannels < 2) {
            continue;
        }
        cout << i << ". " << deviceInfo->name << " (" << Pa_GetHostApiInfo(deviceInfo->hostApi)->name << ")" << endl;
    }
    PaHostApiIndex paDeviceIndex;
    for(;;) { // loop for input until valid choice is made
        string input;
        getline(cin, input);
        try {
            paDeviceIndex = stoi(input);
            if(     paDeviceIndex >= 0 &&
                    paDeviceIndex < paDeviceCount &&
                    Pa_GetDeviceInfo(paDeviceIndex)->maxOutputChannels >= 2) {
                break;
            }
        } catch(...) { } // stoi() throws an exeption for invalid integers
        cout << "Invalid selection" << endl;   
    }

    // Start MIDI timer and open MIDI input
    Pt_Start(1, ptCallback, this);
    PmError pmError = Pm_OpenInput(
        &pmStream,
        pmDeviceIndex,
        NULL,
        8,
        NULL,
        NULL);
    if(pmErr != pmNoError) {
        handlePMError(pmErr);
    }

    // Configure/start audio output stream
    PaStreamParameters paStreamParams;
    paStreamParams.device = paDeviceIndex;
    paStreamParams.channelCount = 2;
    paStreamParams.sampleFormat = paFloat32;
    paStreamParams.suggestedLatency = 512.0 / SAMPLE_RATE;
    paStreamParams.hostApiSpecificStreamInfo = NULL;
    paErr = Pa_OpenStream(
        &paStream,
        NULL,               // no input channels
        &paStreamParams,    // stereo output
        SAMPLE_RATE,
        0,                  // frames per buffer
        paNoFlag,
        paCallback,
        &synth);
    if(paErr != paNoError) {
        handlePAError(paErr);
    }
    paErr = Pa_StartStream(paStream);
    if(paErr != paNoError) { 
        handlePAError(paErr);
    }

    const PaStreamInfo *paStreamInfo = Pa_GetStreamInfo(paStream);
    cout << "Latency: " << round(1000 * paStreamInfo->outputLatency) << " ms" << endl;

    wxFrame *frame = new SynthFrame();
    frame->Show(true);
    return true;
}

int SynthApp::OnExit() {
    Pt_Stop();

    PaError paErr = Pa_StopStream(paStream);
    if(paErr != paNoError) {
        handlePAError(paErr);
    }
    paErr = Pa_CloseStream(paStream);
    if(paErr != paNoError) {
        handlePAError(paErr);
    }
    PmError pmErr = Pm_Close(pmStream);
    if(pmErr != pmNoError) {
        handlePMError(pmErr);
    }
    Pa_Terminate();
    cout << "Terminating" << endl;

    return 0;
}

wxIMPLEMENT_APP(SynthApp);