如何在Cocoa中关闭蓝牙设备和声音设备？

我已经知道机场可以通过CoreWLAN框架关闭。如何在Cocoa中关闭蓝牙设备和声音设备？

所以，我认为可能有与蓝牙设备和声音设备相关的功能或框架。

如何关闭该设备？

来源

2011-03-02 Hwansoo Kim

你是什么意思“关闭”一个声音设备？对于蓝牙，请查看blueutil的源代码 - http://www.frederikseiffert.de/blueutil/ – 2011-03-02 05:55:20

我的意思是声音设备无法通电，因此无法说话。并感谢您的链接 – 2011-03-02 06:02:56

我假设你是“不能有权力，所以它不会说话”，你的意思是你只是想让扬声器静音。我在这里发现了一些简洁的示例代码，使用CoreAudio将系统的默认扬声器静音：http://cocoadev.com/index.pl?SoundVolume

我冒昧地将它转换为纯C并试用它。

#import <CoreAudio/CoreAudio.h> 
#import <stdio.h> 

// getting system volume 

float getVolume() { 
    float   b_vol; 
    OSStatus  err; 
    AudioDeviceID device; 
    UInt32   size; 
    UInt32   channels[2]; 
    float   volume[2]; 

    // get device 
    size = sizeof device; 
    err = AudioHardwareGetProperty(kAudioHardwarePropertyDefaultOutputDevice, &size, &device); 
    if(err!=noErr) { 
     printf("audio-volume error get device\n"); 
     return 0.0; 
    } 

    // try set master volume (channel 0) 
    size = sizeof b_vol; 
    err = AudioDeviceGetProperty(device, 0, 0, kAudioDevicePropertyVolumeScalar, &size, &b_vol); //kAudioDevicePropertyVolumeScalarToDecibels 
    if(noErr==err) return b_vol; 

    // otherwise, try seperate channels 
    // get channel numbers 
    size = sizeof(channels); 
    err = AudioDeviceGetProperty(device, 0, 0,kAudioDevicePropertyPreferredChannelsForStereo, &size,&channels); 
    if(err!=noErr) printf("error getting channel-numbers\n"); 

     size = sizeof(float); 
     err = AudioDeviceGetProperty(device, channels[0], 0, kAudioDevicePropertyVolumeScalar, &size, &volume[0]); 
     if(noErr!=err) printf("error getting volume of channel %d\n",channels[0]); 
      err = AudioDeviceGetProperty(device, channels[1], 0, kAudioDevicePropertyVolumeScalar, &size, &volume[1]); 
      if(noErr!=err) printf("error getting volume of channel %d\n",channels[1]); 

       b_vol = (volume[0]+volume[1])/2.00; 

       return b_vol; 
} 


// setting system volume 
void setVolume(float involume) { 
    OSStatus  err; 
    AudioDeviceID  device; 
    UInt32   size; 
    Boolean   canset = false; 
    UInt32   channels[2]; 
    //float   volume[2]; 

    // get default device 
    size = sizeof device; 
    err = AudioHardwareGetProperty(kAudioHardwarePropertyDefaultOutputDevice, &size, &device); 
    if(err!=noErr) { 
     printf("audio-volume error get device\n"); 
     return; 
    } 


    // try set master-channel (0) volume 
    size = sizeof canset; 
    err = AudioDeviceGetPropertyInfo(device, 0, false, kAudioDevicePropertyVolumeScalar, &size, &canset); 
    if(err==noErr && canset==true) { 
     size = sizeof involume; 
     err = AudioDeviceSetProperty(device, NULL, 0, false, kAudioDevicePropertyVolumeScalar, size, &involume); 
     return; 
    } 

    // else, try seperate channes 
    // get channels 
    size = sizeof(channels); 
    err = AudioDeviceGetProperty(device, 0, false, kAudioDevicePropertyPreferredChannelsForStereo, &size,&channels); 
    if(err!=noErr) { 
     printf("error getting channel-numbers\n"); 
     return; 
    } 

    // set volume 
    size = sizeof(float); 
    err = AudioDeviceSetProperty(device, 0, channels[0], false, kAudioDevicePropertyVolumeScalar, size, &involume); 
    if(noErr!=err) printf("error setting volume of channel %d\n",channels[0]); 
     err = AudioDeviceSetProperty(device, 0, channels[1], false, kAudioDevicePropertyVolumeScalar, size, &involume); 
     if(noErr!=err) printf("error setting volume of channel %d\n",channels[1]); 

} 




int main() { 
    printf("The system's volume is currently %f\n", getVolume()); 
    printf("Setting volume to 0.\n"); 
    setVolume(0.0f); 
    return 0; 
}

我跑，并得到这样的：

[04:29:03] [[email protected] ~/Documents/Programming/c]$ gcc -framework CoreAudio -o mute.o coreaudio.c 
.. snipped compiler output.. 
[04:29:26] [[email protected] ~/Documents/Programming/c]$ ./mute.o 
The system's volume is currently 0.436749 
Setting volume to 0.

希望这向您发送了正确的方向。

来源

2011-03-10 10:34:56 wjl

如何在Cocoa中关闭蓝牙设备和声音设备？

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