strawberry-audio-player-windows-mac-linux/src/engine/alsadevicefinder.cpp

/*
 * Strawberry Music Player
 * Copyright 2017-2021, Jonas Kvinge <jonas@jkvinge.net>
 *
 * Strawberry 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 3 of the License, or
 * (at your option) any later version.
 *
 * Strawberry 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 should have received a copy of the GNU General Public License
 * along with Strawberry.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include "config.h"

#include <cstdio>
#include <cerrno>
#include <alsa/asoundlib.h>

#include <QString>
#include <QScopeGuard>

#include <core/logging.h>

#include "alsadevicefinder.h"
#include "enginedevice.h"

AlsaDeviceFinder::AlsaDeviceFinder() : DeviceFinder(QStringLiteral("alsa"), { QStringLiteral("alsa"), QStringLiteral("alsasink") }) {}

EngineDeviceList AlsaDeviceFinder::ListDevices() {

  EngineDeviceList devices;

  snd_pcm_stream_name(SND_PCM_STREAM_PLAYBACK);

  int card = -1;
  snd_ctl_card_info_t *cardinfo = nullptr;
  snd_ctl_card_info_alloca(&cardinfo);
  while (true) {

    int result = snd_card_next(&card);
    if (result < 0) {
      qLog(Error) << "Unable to get soundcard:" << snd_strerror(result);
      break;
    }
    if (card < 0) break;

    char str[32];
    snprintf(str, sizeof(str) - 1, "hw:%d", card);

    snd_ctl_t *handle = nullptr;
    result = snd_ctl_open(&handle, str, 0);
    if (result < 0) {
      qLog(Error) << "Unable to open soundcard" << card << ":" << snd_strerror(result);
      continue;
    }
    const QScopeGuard snd_ctl_handle_close = qScopeGuard([&handle]() { snd_ctl_close(handle); });

    result = snd_ctl_card_info(handle, cardinfo);
    if (result < 0) {
      qLog(Error) << "Control hardware failure for card" << card << ":" << snd_strerror(result);
      continue;
    }

    int dev = -1;
    snd_pcm_info_t *pcminfo = nullptr;
    snd_pcm_info_alloca(&pcminfo);
    while (true) {

      result = snd_ctl_pcm_next_device(handle, &dev);
      if (result < 0) {
        qLog(Error) << "Unable to get PCM for card" << card << ":" << snd_strerror(result);
        continue;
      }
      if (dev < 0) break;

      snd_pcm_info_set_device(pcminfo, dev);
      snd_pcm_info_set_subdevice(pcminfo, 0);
      snd_pcm_info_set_stream(pcminfo, SND_PCM_STREAM_PLAYBACK);

      result = snd_ctl_pcm_info(handle, pcminfo);
      if (result < 0) {
        if (result != -ENOENT) qLog(Error) << "Unable to get control digital audio info for card" << card << ":" << snd_strerror(result);
        continue;
      }

      EngineDevice device;
      device.description = QStringLiteral("%1 %2").arg(QString::fromUtf8(snd_ctl_card_info_get_name(cardinfo)), QString::fromUtf8(snd_pcm_info_get_name(pcminfo)));
      device.iconname = device.GuessIconName();
      device.card = card;
      device.device = dev;

      device.value = QStringLiteral("hw:%1,%2").arg(card).arg(dev);
      devices.append(device);
      device.value = QStringLiteral("plughw:%1,%2").arg(card).arg(dev);
      devices.append(device);

    }
  }

  snd_config_update_free_global();

  return devices;
}