C++ snd_mixer_load函数代码示例

/**
 * 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;
        }
}

bool AlsaMixer::Init( const char* card )
{
	LOG( Logger::LOG_DEBUG, "AlsaMixer::Init( %s )", card);
	int err = 0;
	bool success = false;

	if ( (err = snd_mixer_open(&_handle, 0)) < 0 ) {
		LOG( Logger::LOG_ERROR, "Mixer %s open error: %s", card, snd_strerror(err));
		_handle = NULL;
		goto end;
	}
	if( (err = snd_mixer_attach(_handle, card)) < 0) {
		LOG( Logger::LOG_ERROR, "Mixer %s attach error: %s", card, snd_strerror(err));
		goto end;
	}
	if ((err = snd_mixer_selem_register(_handle, NULL, NULL)) < 0) {
		LOG( Logger::LOG_ERROR, "Mixer register error: %s", snd_strerror(err));
		goto end;
	}
	if ((err = snd_mixer_load(_handle)) < 0) {
		LOG( Logger::LOG_ERROR, "Mixer %s load error: %s", card, snd_strerror(err));
		goto end;
	}
	success = true;
 end:
	if( !success )
	{
		if( _handle ) {
			snd_mixer_close(_handle);
			_handle = NULL;
		}
	}
	return success;
}

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);
}

void mixerGuiAlsaMix::cardChanged( int card )
{
#ifdef HAVE_ALSA
	channelSelect->clear();
	// get the cards channels
	snd_mixer_t* alsaDev;
	snd_mixer_open( &alsaDev, 0);
	char device[16];
	sprintf(device, "hw:%i", card);
	snd_mixer_attach(alsaDev, device );
	snd_mixer_selem_register(alsaDev, NULL, NULL);
	snd_mixer_load(alsaDev);  //load up the mixer

	snd_mixer_elem_t* mixerElem = snd_mixer_first_elem(alsaDev);
	while( mixerElem != snd_mixer_last_elem(alsaDev) )
	{
	    if(snd_mixer_selem_has_playback_volume(mixerElem) || snd_mixer_selem_has_capture_volume(mixerElem))
		channelSelect->addItem( QString( snd_mixer_selem_get_name(mixerElem)), QVariant( snd_mixer_selem_get_name(mixerElem)) );
	    mixerElem=snd_mixer_elem_next( mixerElem );
	}

	for(int i=0; i<= channelSelect->count(); i++ )
	    if( channelSelect->itemData(i) == settings["alsa_channel"].toString() )
		channelSelect->setCurrentIndex( i );
#endif
}

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 NeoControl::openAlsaMixer()
{
    system("alsactl -f /opt/qtmoko/etc/alsa-scenarios/gsmhandset.state restore");

    int ret = 0;
    QString text(tr("Call volume settings\n\n"));

    if ((ret = snd_mixer_open(&mixerFd, 0)) < 0) {
        text += QString("snd_mixer_open error %1").arg(ret);
        goto err;
    }
    if ((ret = snd_mixer_attach(mixerFd, "default")) < 0) {
        text += QString("snd_mixer_attach error %1").arg(ret);
        goto err;
    }
    if ((ret = snd_mixer_selem_register(mixerFd, NULL, NULL)) < 0) {
        text += QString("snd_mixer_selem_register error %1").arg(ret);
        goto err;
    }
    if ((ret = snd_mixer_load(mixerFd)) < 0) {
        text += QString("snd_mixer_load error %1").arg(ret);
        goto err;
    }

    goto ok;

err:
    if (mixerFd)
        snd_mixer_close(mixerFd);
    mixerFd = NULL;
ok:
    label->setText(text);

    return ret;
}

/**
 * Opens the mixer, attaches the alsa card to it,
 * registers the mixer simple element class and
 * loads the mixer elements.
 *
 * @param card HCTL name
 * @param opts Options container
 * @param level mixer level
 * @return the mixer handle, or NULL on failure
 */
static snd_mixer_t *
open_mixer(const char *card, struct snd_mixer_selem_regopt *opts, int level)
{
    int err;
    snd_mixer_t *mixer = NULL;

    DEBUG_PRINT("Card %s: opening mixer", card);

    if ((err = snd_mixer_open(&mixer, 0)) < 0) {
        DEBUG_PRINT("Card %s: mixer open error: %s", card, snd_strerror(err));
        return NULL;
    }
    if (level == 0 && (err = snd_mixer_attach(mixer, card)) < 0) {
        DEBUG_PRINT("Card %s: mixer attach error: %s", card,
                    snd_strerror(err));
        snd_mixer_close(mixer);
        return NULL;
    }
    if ((err = snd_mixer_selem_register(
                   mixer, level > 0 ? opts : NULL, NULL)) < 0) {
        DEBUG_PRINT("Card %s: mixer register error: %s", card,
                    snd_strerror(err));
        snd_mixer_close(mixer);
        return NULL;
    }
    if ((err = snd_mixer_load(mixer)) < 0) {
        DEBUG_PRINT("Card %s: mixer load error: %s", card, snd_strerror(err));
        snd_mixer_close(mixer);
        return NULL;
    }

    return mixer;
}

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);
}

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;
}

int AmeSystemSound::getMixer(snd_mixer_t **mixer, QString card)
{
	char *dev;
	int err;
	
	dev = strdup(card.toAscii().data());
	if ((err = snd_mixer_open(mixer, 0)) < 0) {
		qWarning("SoundOutput: Failed to open empty mixer: %s", snd_strerror(-err));
		mixer = NULL;
		return -1;
	}
	
	if ((err = snd_mixer_attach(*mixer, dev)) < 0) {
		qWarning("SoundOutput: Attaching to mixer %s failed: %s", dev, snd_strerror(-err));
		return -1;
	}
    
	if ((err = snd_mixer_selem_register(*mixer, NULL, NULL)) < 0) {
		qWarning("SoundOutput: Failed to register mixer: %s", snd_strerror(-err));
		return -1;
	}
	
	if ((err = snd_mixer_load(*mixer)) < 0) {
		qWarning("SoundOutput: Failed to load mixer: %s", snd_strerror(-err));
		return -1;
	}
	
	free(dev);
	return (*mixer != NULL);
}

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);

}

/**
 *  @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);
}

int initMixer()
{
  int result;
  if ((result = snd_mixer_open( &mixerFd, 0)) < 0) {
        printf("sucks1!\n");
        mixerFd = NULL;
        return result;
    }
    
    if ((result = snd_mixer_attach( mixerFd, "default")) < 0) {
        printf("snd_mixer_attach error");
        snd_mixer_close(mixerFd);
        mixerFd = NULL;
        return result;
    }
    if ((result = snd_mixer_selem_register( mixerFd, NULL, NULL)) < 0) {
        printf("snd_mixer_selem_register error");
        snd_mixer_close(mixerFd);
        mixerFd = NULL;
        return result;
    }
    if ((result = snd_mixer_load( mixerFd)) < 0) {
        printf("snd_mixer_load error");
        snd_mixer_close(mixerFd);
        mixerFd = NULL;
        return result;
    }
    return result;
}

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;
}

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);
}