C++ snd_mixer_selem_id_set_name函数代码示例

char *get_vol(char *buf) {
	long max = 0, min = 0, vol = 0;
	int mute = 0;

	snd_mixer_t *handle;
	snd_mixer_elem_t *pcm_mixer, *mas_mixer;
	snd_mixer_selem_id_t *vol_info, *mute_info;

	snd_mixer_open(&handle, 0);
	snd_mixer_attach(handle, "default");
	snd_mixer_selem_register(handle, NULL, NULL);
	snd_mixer_load(handle);
	snd_mixer_selem_id_malloc(&vol_info);
	snd_mixer_selem_id_malloc(&mute_info);
	snd_mixer_selem_id_set_name(vol_info, VOL_CH);
	snd_mixer_selem_id_set_name(mute_info, VOL_CH);
	pcm_mixer = snd_mixer_find_selem(handle, vol_info);
	mas_mixer = snd_mixer_find_selem(handle, mute_info);
	snd_mixer_selem_get_playback_volume_range((snd_mixer_elem_t *)pcm_mixer, &min, &max);
	snd_mixer_selem_get_playback_volume((snd_mixer_elem_t *)pcm_mixer, SND_MIXER_SCHN_MONO, &vol);
	snd_mixer_selem_get_playback_switch(mas_mixer, SND_MIXER_SCHN_MONO, &mute);
	sprintf(buf, !(mute) ? VOL_MUTE_S : VOL_S, (int)vol * 100 / (int)max);
	if(vol_info)
		snd_mixer_selem_id_free(vol_info);
	if(mute_info)
		snd_mixer_selem_id_free(mute_info);
	if(handle)
		snd_mixer_close(handle);
	return buf;
}

char *getvolume() {
    char *buf;
    int active;
    long volume, min, max;
    snd_mixer_t *handle;
    snd_mixer_selem_id_t *sid;
    snd_mixer_elem_t* elem;
    const char *card = "default";
    const char *selem_name = "Master";

    snd_mixer_open(&handle, 0);
    snd_mixer_attach(handle, card);
    snd_mixer_selem_register(handle, NULL, NULL);
    snd_mixer_load(handle);

    snd_mixer_selem_id_alloca(&sid);
    snd_mixer_selem_id_set_index(sid, 0);
    snd_mixer_selem_id_set_name(sid, selem_name);
    elem = snd_mixer_find_selem(handle, sid);

    snd_mixer_selem_get_playback_volume_range(elem, &min, &max);
    snd_mixer_selem_get_playback_volume(elem, SND_MIXER_SCHN_FRONT_LEFT, &volume);
    snd_mixer_selem_get_playback_switch(elem, SND_MIXER_SCHN_FRONT_LEFT, &active);

    buf = xmalloc(10);
    if (active)
        snprintf(buf, 10, "%0.f%%", (double) volume / (double) max * 100);
    else
        snprintf(buf, 10, "off");

    snd_mixer_close(handle);

    return buf;
}

/**
 * init_alsa
 * must be called before other alsa functions
 * only needs to be called once
 * initializes alsa handle
 */
void
init_alsa()
{
        snd_mixer_open(&alsa, 0);
        snd_mixer_attach(alsa, SOUNDCARD);
        snd_mixer_selem_register(alsa, NULL, NULL);
        snd_mixer_load(alsa);

        if (alsa == NULL)
        {
                fprintf(stderr, "error opening sound card " SOUNDCARD);
                return;
        }

        snd_mixer_selem_id_t *sid;
        snd_mixer_selem_id_alloca(&sid);
        snd_mixer_selem_id_set_index(sid, 0);
        snd_mixer_selem_id_set_name(sid, ALSAMIXER);
        alsamixer = snd_mixer_find_selem(alsa, sid);

        if (alsamixer == NULL)
        {
                fprintf(stderr, "error opening alsa mixer " ALSAMIXER);
                return;
        }
}

void SetAlsaSwitchMute(const char* card, const char* selem_name) {
    // long min, max;
    snd_mixer_t *handle;
    snd_mixer_selem_id_t *sid;

    snd_mixer_open(&handle, 0);
    snd_mixer_attach(handle, card);
    snd_mixer_selem_register(handle, NULL, NULL);
    snd_mixer_load(handle);

    snd_mixer_selem_id_alloca(&sid);
    snd_mixer_selem_id_set_index(sid, 0);
    snd_mixer_selem_id_set_name(sid, selem_name);
    snd_mixer_elem_t* elem = snd_mixer_find_selem(handle, sid);
    
    int* muted;
    snd_mixer_selem_channel_id_t channel;
    
    snd_mixer_selem_get_playback_switch(elem,channel,muted);
    printf("Muted: %d\n",*muted);	

    if (snd_mixer_selem_has_playback_switch(elem)) {
        snd_mixer_selem_set_playback_switch_all(elem, !*muted);
    }

    snd_mixer_close(handle);
}

mixerVolume::mixerVolume(const char *name, const char *card, long volume) {
	snd_mixer_selem_id_t *sid = NULL;
	elem = NULL;
	handle = NULL;
	min = 0;
	max = 100;
	char cardId[10];

	if (!name || !card)
		return;

	int cx = snd_card_get_index(card);
	if (cx < 0 || cx > 31)
		return;
	snprintf(cardId, sizeof(cardId), "hw:%i", cx);

	if (0 > snd_mixer_open(&handle, 0))
		return;
	if (0 > snd_mixer_attach(handle, cardId))
		return;
	if (0 > snd_mixer_selem_register(handle, NULL, NULL))
		return;
	if (0 > snd_mixer_load(handle))
		return;
	snd_mixer_selem_id_alloca(&sid);
	if (!sid)
		return;
	snd_mixer_selem_id_set_index(sid, 0);
	snd_mixer_selem_id_set_name(sid, name);
	elem = snd_mixer_find_selem(handle, sid);
	if (elem) {
		snd_mixer_selem_get_playback_volume_range(elem, &min, &max);
		setVolume(volume);
	}
}

void set_volume(int vol)
{
	long min, max;
	snd_mixer_t *handlev;
	snd_mixer_selem_id_t *sid;
	const char *card = "default";
	const char *selem_name = "Master";

	if (vol < 1 || vol > 100) {
		printf("ERROR: Volume out of range [0,100] %%\n");
		printf("\tSetting volume to 50%%...\n");
		vol = 50;
	}

	snd_mixer_open(&handlev, 0);
	snd_mixer_attach(handlev, card);
	snd_mixer_selem_register(handlev, NULL, NULL);
	snd_mixer_load(handlev);

	snd_mixer_selem_id_alloca(&sid);
	snd_mixer_selem_id_set_index(sid, 0);
	snd_mixer_selem_id_set_name(sid, selem_name);
	snd_mixer_elem_t *elem = snd_mixer_find_selem(handlev, sid);

	snd_mixer_selem_get_playback_volume_range(elem, &min, &max);
	snd_mixer_selem_set_playback_volume_all(elem, vol * max / 100 + min);

	snd_mixer_close(handlev);
}

/**
 *  @brief Get the Volume for the master channel.
 *
 *    This function uses the Alsa API to get the volume
 *    for the master channel.
 *
 *  @param [out] ptr pointer to long, output will be between 0 and 99.
 *  @return Void.
 */
void get_volume(long *ptr){
  long min, max;
  snd_mixer_t *handle;
  snd_mixer_selem_id_t *sid;
  const char *card = "default";
  //const char *selem_name = "Master";
  const char *selem_name = "DAC2 Digital Course";

  snd_mixer_open(&handle, 0);
  snd_mixer_attach(handle, card);
  snd_mixer_selem_register(handle, NULL, NULL);
  snd_mixer_load(handle);

  snd_mixer_selem_id_alloca(&sid);
  snd_mixer_selem_id_set_index(sid, 0);
  snd_mixer_selem_id_set_name(sid, selem_name);
  snd_mixer_elem_t* elem = snd_mixer_find_selem(handle, sid);

  snd_mixer_selem_get_playback_volume_range(elem, &min, &max);
  printd("Volume range <%lu,%lu>\n", min, max);
  snd_mixer_selem_get_playback_volume(elem,0,ptr);
  printd("volume val = %lu\n",*ptr);
  *ptr /= (max / 100);
  snd_mixer_close(handle);
}

static snd_mixer_elem_t *alsa_init_mixer_channel (const char *name,
		long *vol_min, long *vol_max)
{
	snd_mixer_selem_id_t *sid;
	snd_mixer_elem_t *elem = NULL;
	
	snd_mixer_selem_id_malloc (&sid);
	snd_mixer_selem_id_set_index (sid, 0);
	snd_mixer_selem_id_set_name (sid, name);

	if (!(elem = snd_mixer_find_selem(mixer_handle, sid)))
		error ("Can't find mixer %s", name);
	else if (!snd_mixer_selem_has_playback_volume(elem)) {
		error ("Mixer device has no playback volume (%s).", name);
		elem = NULL;
	}
	else {
		snd_mixer_selem_get_playback_volume_range (elem, vol_min,
				vol_max);
		logit ("Opened mixer (%s), volume range: %ld-%ld", name,
				*vol_min, *vol_max);
	}

	snd_mixer_selem_id_free (sid);

	return elem;
}

void set_volume(GtkAdjustment *adjustment, gpointer user_data)
{
  int value = (int) 100 - gtk_adjustment_get_value(adjustment);
  g_debug("Setting master volume to: %d", value);

  if(value == 0)
    gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(s_mute), TRUE);
  else
    gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(s_mute), FALSE);

  long min, max;
  snd_mixer_t *mix;
  snd_mixer_selem_id_t *sid;
  const char *card = "default";
  const char *selem_name = "Master";

  snd_mixer_open(&mix, 0);
  snd_mixer_attach(mix, card);
  snd_mixer_selem_register(mix, NULL, NULL);
  snd_mixer_load(mix);

  snd_mixer_selem_id_alloca(&sid);
  snd_mixer_selem_id_set_index(sid, 0);
  snd_mixer_selem_id_set_name(sid, selem_name);
  snd_mixer_elem_t* elem = snd_mixer_find_selem(mix, sid);

  snd_mixer_selem_get_playback_volume_range(elem, &min, &max);
  snd_mixer_selem_set_playback_volume_all(elem, value * max / 100);

  snd_mixer_close(mix);

}

int volume_up(int vol_min, int vol_max)
{
    long min, max;
    snd_mixer_t *handle;
    snd_mixer_selem_id_t *sid;
    const char *card = "default";
    const char *selem_name = "Master";


    snd_mixer_open(&handle, 0);
    snd_mixer_attach(handle, card);
    snd_mixer_selem_register(handle, NULL, NULL);
    snd_mixer_load(handle);

    snd_mixer_selem_id_alloca(&sid);
    snd_mixer_selem_id_set_index(sid, 0);
    snd_mixer_selem_id_set_name(sid, selem_name);
    snd_mixer_elem_t* elem = snd_mixer_find_selem(handle, sid);

    snd_mixer_selem_get_playback_volume_range(elem, &min, &max);
    
    for (int i = vol_min; i<vol_max; i++) {
      
      int v = i*max /100;
      snd_mixer_selem_set_playback_volume_all(elem, v);
      //printf("min = %d, max= %d, volume = %d\n", min, max, volume);
      usleep(50000);
    }
    snd_mixer_close(handle);
}

void asound_set_channel(const gchar * channel)
{
    if(m_mixer == NULL || channel == NULL) {
        return;
    }
    if(g_strcmp0(channel, m_channel) == 0)
        return;

    // Clean up any previously set channels
    g_free(m_channel);
    m_channel = g_strdup(channel);
    if(m_elem)
    {
        snd_mixer_elem_set_callback(m_elem, NULL);
        m_elem = NULL;
    }

    // Setup m_elem using the provided channelname
    snd_mixer_selem_id_t * sid;
    snd_mixer_selem_id_malloc(&sid);
    snd_mixer_selem_id_set_name(sid, channel);
    m_elem = snd_mixer_find_selem(m_mixer, sid);
    if(m_elem != NULL)
    {
        snd_mixer_elem_set_callback(m_elem, asound_elem_event);
        snd_mixer_selem_id_free(sid);
    }
}

static long get_master_volume()
{
    snd_mixer_t *handle;
    snd_mixer_open(&handle, 0);
    snd_mixer_attach(handle, Y50_CTL_NAME);
    snd_mixer_selem_register(handle, NULL, NULL);
    snd_mixer_load(handle);

    snd_mixer_selem_id_t *master_sid;
    const char *master_selem_name = "Master";

    snd_mixer_selem_id_alloca(&master_sid);
    snd_mixer_selem_id_set_index(master_sid, 0);
    snd_mixer_selem_id_set_name(master_sid, master_selem_name);
    snd_mixer_elem_t* elem = snd_mixer_find_selem(handle, master_sid);

    long min, max;
    snd_mixer_selem_get_playback_volume_range(elem, &min, &max);

    long volume;
    snd_mixer_selem_get_playback_volume(elem, SND_MIXER_SCHN_MONO, &volume);

    snd_mixer_close(handle);

    return volume * 100 / max;
}

int volume_set(int volume)
{
    long min, max;
    snd_mixer_t *handle;
    snd_mixer_selem_id_t *sid;
    const char *card = "default";
    //const char *selem_name = "Master";
    const char *selem_name = "Digital";


    snd_mixer_open(&handle, 0);
    snd_mixer_attach(handle, card);
    snd_mixer_selem_register(handle, NULL, NULL);
    snd_mixer_load(handle);

    snd_mixer_selem_id_alloca(&sid);
    snd_mixer_selem_id_set_index(sid, 0);
    snd_mixer_selem_id_set_name(sid, selem_name);
    snd_mixer_elem_t* elem = snd_mixer_find_selem(handle, sid);

    snd_mixer_selem_get_playback_volume_range(elem, &min, &max);
    
      
    int v = volume*max /100;
    snd_mixer_selem_set_playback_volume_all(elem, v);
    snd_mixer_close(handle);
    return v;
}

bool AlsaMixer::GetVolumePercent( const char* channel, int* value )
{
	LOG( Logger::LOG_DEBUG, "AlsaMixer::GetVolume( %s )", channel);
	bool success = false;
	snd_mixer_elem_t *elem;
	snd_mixer_selem_id_t *sid;
	snd_mixer_selem_id_alloca(&sid);

	snd_mixer_selem_id_set_index( sid, 0);
	snd_mixer_selem_id_set_name( sid, channel);
	elem = snd_mixer_find_selem(_handle, sid);
	if (!elem) {
		LOG( Logger::LOG_ERROR, "Unable to find simple control '%s',%i\n", snd_mixer_selem_id_get_name(sid), snd_mixer_selem_id_get_index(sid));
		goto end;
	}
	if( snd_mixer_selem_has_playback_volume(elem) )
	{
		long min, max;
		if( snd_mixer_selem_get_playback_volume_range(elem, &min, &max) < 0 )
		{
			LOG( Logger::LOG_ERROR, "Unable to get playback volume range for control '%s',%i\n", snd_mixer_selem_id_get_name(sid), snd_mixer_selem_id_get_index(sid));
			goto end;
		}
		long volume;
		for (int chn = 0; chn <= SND_MIXER_SCHN_LAST; chn++) {
			if (snd_mixer_selem_get_playback_volume(elem, (snd_mixer_selem_channel_id_t)chn, &volume ) >= 0)
			{
				*value = (volume - min) * 100 / ( max - min );
				success = true;
				break;
			}
		}
	}else if( snd_mixer_selem_has_capture_volume(elem) )
	{
		long min, max;
		if( snd_mixer_selem_get_capture_volume_range(elem, &min, &max) < 0 )
		{
			LOG( Logger::LOG_ERROR, "Unable to get capture volume range for control '%s',%i\n", snd_mixer_selem_id_get_name(sid), snd_mixer_selem_id_get_index(sid));
			goto end;
		}
		long volume;
		for (int chn = 0; chn <= SND_MIXER_SCHN_LAST; chn++) {
			if (snd_mixer_selem_get_capture_volume(elem, (snd_mixer_selem_channel_id_t)chn, &volume ) >= 0)
			{
				*value = (volume - min) * 100 / ( max - min );
				success = true;
				break;
			}
		}
	}
	if( !success )
	{
		LOG( Logger::LOG_ERROR, "Error getting control '%s',%i\n", snd_mixer_selem_id_get_name(sid), snd_mixer_selem_id_get_index(sid));
	}
 end:
	return success;
}

/*
 * originally from
 * stackoverflow.com/questions/7657624/get-master-sound-volume-in-c-in-linux
 */
static int get_audio_volume(MixSelect select, long* outvol) {
	int ret = 0;
	snd_mixer_t* handle;
	snd_mixer_elem_t* elem;
	snd_mixer_selem_id_t* sid;
	long minv, maxv;

	snd_mixer_selem_id_alloca(&sid);

	snd_mixer_selem_id_set_index(sid, select.mix_index);
	snd_mixer_selem_id_set_name(sid, select.mix_name);

	if ((snd_mixer_open(&handle, 0)) < 0) {
		return -1;
	}

	if ((snd_mixer_attach(handle, select.card)) < 0) {
		snd_mixer_close(handle);
		return -2;
	}

	if ((snd_mixer_selem_register(handle, NULL, NULL)) < 0) {
		snd_mixer_close(handle);
		return -3;
	}

	ret = snd_mixer_load(handle);

	if (ret < 0) {
		snd_mixer_close(handle);
		return -4;
	}

	elem = snd_mixer_find_selem(handle, sid);

	if (!elem) {
		snd_mixer_close(handle);
		return -5;
	}

	snd_mixer_selem_get_playback_volume_range(elem, &minv, &maxv);

	if(snd_mixer_selem_get_playback_volume(elem, 0, outvol) < 0) {
		snd_mixer_close(handle);
		return -6;
	}

	// make volume out of 100
	*outvol -= minv;
	maxv -= minv;
	minv = 0;
	*outvol = 100 * (*outvol) / maxv;

	snd_mixer_close(handle);
	return 0;
}