squeezelite-esp32/components/spotify/cspot/bell/main/audio-sinks/unix/ALSAAudioSink.cpp

#include "ALSAAudioSink.h"

ALSAAudioSink::ALSAAudioSink() : Task("", 0, 0, 0)
{
    /* Open the PCM device in playback mode */
    if (pcm = snd_pcm_open(&pcm_handle, PCM_DEVICE,
                           SND_PCM_STREAM_PLAYBACK, 0) < 0)
    {
        printf("ERROR: Can't open \"%s\" PCM device. %s\n",
               PCM_DEVICE, snd_strerror(pcm));
    }

    /* Allocate parameters object and fill it with default values*/
    snd_pcm_hw_params_alloca(&params);

    snd_pcm_hw_params_any(pcm_handle, params);

    /* Set parameters */
    if (pcm = snd_pcm_hw_params_set_access(pcm_handle, params,
                                           SND_PCM_ACCESS_RW_INTERLEAVED) < 0)
        printf("ERROR: Can't set interleaved mode. %s\n", snd_strerror(pcm));

    if (pcm = snd_pcm_hw_params_set_format(pcm_handle, params,
                                           SND_PCM_FORMAT_S16_LE) < 0)
        printf("ERROR: Can't set format. %s\n", snd_strerror(pcm));

    if (pcm = snd_pcm_hw_params_set_channels(pcm_handle, params, 2) < 0)
        printf("ERROR: Can't set channels number. %s\n", snd_strerror(pcm));
    unsigned int rate = 44100;
    if (pcm = snd_pcm_hw_params_set_rate_near(pcm_handle, params, &rate, 0) < 0)
        printf("ERROR: Can't set rate. %s\n", snd_strerror(pcm));
    unsigned int periodTime = 800;
    int dir = -1;
    snd_pcm_hw_params_set_period_time_near(pcm_handle, params, &periodTime, &dir);
    /* Write parameters */
    if (pcm = snd_pcm_hw_params(pcm_handle, params) < 0)
        printf("ERROR: Can't set harware parameters. %s\n", snd_strerror(pcm));

    /* Resume information */
    printf("PCM name: '%s'\n", snd_pcm_name(pcm_handle));

    printf("PCM state: %s\n", snd_pcm_state_name(snd_pcm_state(pcm_handle)));
    unsigned int tmp;
    snd_pcm_hw_params_get_channels(params, &tmp);
    printf("channels: %i ", tmp);
    if (tmp == 1)
        printf("(mono)\n");
    else if (tmp == 2)
        printf("(stereo)\n");

    snd_pcm_hw_params_get_period_time(params, &tmp, NULL);
    printf("period_time = %d\n", tmp);
    snd_pcm_hw_params_get_period_size(params, &frames, 0);

    this->buff_size = frames * 2 * 2 /* 2 -> sample size */;
    printf("required buff_size: %d\n", buff_size);
    this->startTask();
}

ALSAAudioSink::~ALSAAudioSink()
{
    snd_pcm_drain(pcm_handle);
    snd_pcm_close(pcm_handle);
}

void ALSAAudioSink::runTask()
{
    std::unique_ptr<std::vector<uint8_t>> dataPtr;
    while (true)
    {
        if (!this->ringbuffer.pop(dataPtr))
        {
            usleep(100);
            continue;
        }
        if (pcm = snd_pcm_writei(pcm_handle, dataPtr->data(), this->frames) == -EPIPE)
        {

            snd_pcm_prepare(pcm_handle);
        }
        else if (pcm < 0)
        {
            printf("ERROR. Can't write to PCM device. %s\n", snd_strerror(pcm));
        }
    }
}

void ALSAAudioSink::feedPCMFrames(const uint8_t *buffer, size_t bytes)
{

    buff.insert(buff.end(), buffer, buffer + bytes);
    while (buff.size() > this->buff_size)
    {
        auto ptr = std::make_unique<std::vector<uint8_t>>(this->buff.begin(), this->buff.begin() + this->buff_size);
        this->buff = std::vector<uint8_t>(this->buff.begin() + this->buff_size, this->buff.end());
        while (!this->ringbuffer.push(ptr))
        {
            usleep(100);
        };
    }
}