Raspberry PiでFLACファイル再生するテスト

alsa_flac_test.cpp

/*
 * alsa_flac_test.cpp
 *
 * Created by fukuroda (https://github.com/fukuroder)
 */

// g++ alsa_flac_test.cpp -std=c++0x -O3 -lasound -lsndfile

#include<alsa/asoundlib.h>  // sudo apt-get install libasound2-dev
#include<sndfile.h>         // sudo apt-get install libsndfile1-dev
#include<iostream>
#include<vector>
#include<stdexcept>

int main()
{
    const char* device = "hw:ALSA"; // PWM

    SNDFILE *sf = nullptr;
    snd_pcm_t *pcm = nullptr;
    try
    {
        // open sound file
        SF_INFO info = { 0 };
        sf = ::sf_open("kmb.flac", SFM_READ, &info);
        if( sf == nullptr )
        {
            throw std::runtime_error("sf_open error");
        }

        // open audio device
        if( ::snd_pcm_open(
            &pcm,
            device,
            SND_PCM_STREAM_PLAYBACK,
            0) )
        {
            throw std::runtime_error("snd_pcm_open error");
        }

        // set parameters
        if( ::snd_pcm_set_params(
            pcm,
            SND_PCM_FORMAT_S16,
            SND_PCM_ACCESS_RW_INTERLEAVED,
            2,
            44100,
            0,
            100*1000) ) // 100ms
        {
            throw std::runtime_error("snd_pcm_set_params error");
        }

        // get buffer size and period size
        snd_pcm_uframes_t buffer_size = 0;
        snd_pcm_uframes_t period_size = 0;
        if( ::snd_pcm_get_params(
            pcm,
            &buffer_size,
            &period_size) )
        {
            throw std::runtime_error("snd_pcm_get_params error");
        }

        // allocate buffer
        std::vector<short> buffer(2*period_size);

        std::cout << "start ("
                  << "buffer_size=" << buffer_size << ", "
                  << "period_size=" << period_size << ")"
                  << std::endl;

        sf_count_t read_count = 0;
        do{
            // read
            read_count = ::sf_readf_short(sf, buffer.data(), period_size);

            // write
            if( ::snd_pcm_writei(pcm, buffer.data(), read_count) < 0 )
            {
                throw std::runtime_error("snd_pcm_writei error");
            }
        }while(read_count == period_size);

        std::cout << "end" << std::endl;
    }
    catch(std::exception &ex)
    {
        std::cout << "error:" << ex.what() << std::endl;
    }

    if(pcm != nullptr)
    {
        // close audio device
        ::snd_pcm_close(pcm);
    }

    if(sf != nullptr)
    {
        // close sound file
        ::sf_close(sf);
    }

    return 0;
}