ALSAFullDuplexTest.C

/* Copyright 2000-2018 Matt Flax <flatmax@flatmax.org>
This file is part of GTK+ IOStream class set

GTK+ IOStream 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.

GTK+ IOStream 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 General Public License for more details.

You have received a copy of the GNU General Public License
along with GTK+ IOStream
*/

#include "ALSA/ALSA.H"
#include <iostream>
using namespace std;

using namespace ALSA;

#include "Sox.H"

class FullDuplexTest : public FullDuplex<int> {
        int N; 
        int ch; 

        int process(){
                if (inputAudio.rows()!=N || inputAudio.cols()!=ch){
                        inputAudio.resize(N, ch);
                        outputAudio.resize(N, ch);
                        inputAudio.setZero();
                }
                outputAudio=inputAudio; // copy the input to output.
                return 0; // return 0 to continue
        }
public:
        FullDuplexTest(const char*devName, int latency) : FullDuplex(devName){
                ch=2; // use this static number of input and output channels.
                N=latency;
                inputAudio.resize(0,0); // force zero size to ensure resice on the first process.
                outputAudio.resize(0,0);
        }
};

int main(int argc, char *argv[]) {
        int latency=2048;
        int fs=48000; // The sample rate
        cout<<"latency = "<<(float)latency/(float)fs<<" s"<<endl;

        const char deviceName[]="hw:0";
        FullDuplexTest fullDuplex(deviceName, latency);
        cout<<"opened the device "<<fullDuplex.Playback::getDeviceName()<<endl;
        cout<<"channels max "<<fullDuplex.Playback::getMaxChannels()<<endl;

        // we don't want defaults so reset and refil the params ...
        int res=fullDuplex.resetParams();
        if (res<0)
                return res;

        snd_pcm_format_t format=SND_PCM_FORMAT_S32_LE;
        if ((res=fullDuplex.setFormat(format))<0)
                return res;

        res=fullDuplex.setAccess(SND_PCM_ACCESS_RW_INTERLEAVED);
        if (res<0)
                return res;

        if ((res=fullDuplex.setSampleRate(fs))<0)
                return res;

        res=fullDuplex.go(); // start the full duplex read/write/process going.
        return ALSADebug().evaluateError(res);
}