通過Cocoa應用程序控制Mac上的主音量

Question

我正在尋找將NSSlider併入控制Mac主音量的Cocoa應用程序中。儘管我知道它可能更容易，但我不想通過AppleScript來做到這一點。

我發現這個代碼應該能夠做到這一點，但並不是因爲自10.5 AudioDeviceGetProperty及其一致已被棄用。什麼需要改變，以使這項工作？

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

// get device 
size = sizeof device; 
err = AudioObjectGetPropertyData(kAudioHardwarePropertyDefaultOutputDevice, &device, <#UInt32 inQualifierDataSize#>, <#const void *inQualifierData#>, &size, <#void *outData#>); 
if(err!=noErr) 
{ 
    NSLog(@"audio-volume error get device"); 
    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) NSLog(@"error getting channel-numbers"); 

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

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

return b_vol; 
} 

- (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; 
printf("setVolume:: value of the volume set =%lf", involume); 
err = AudioHardwareGetProperty(kAudioHardwarePropertyDefaultOutputDevice, &size, &device); 
if(err!=noErr) { 
    NSLog(@"audio-volume error get device"); 
    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) { 
    NSLog(@"error getting channel-numbers"); 
    return; 
} 

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

} 

在此先感謝！

Answer 1

這將這樣的伎倆 - 我只是複製並粘貼它從我的項目之一，所以有一些多餘的變量和函數，但你應該能夠得到它的要點：

BOOL gotMaster = NO; 
BOOL gotLeft = NO; 
BOOL gotRight = NO; 
float volume = 1, lvolume = 1, rvolume = 1; 
float inVolume = 1, inLvolume = 1, inRvolume = 1; 
OSStatus result = noErr; 
AudioObjectPropertyAddress thePropertyAddress; 
UInt32 thePropSize = sizeof(Float32); 
thePropertyAddress.mSelector = kAudioDevicePropertyVolumeScalar; 
thePropertyAddress.mScope = kAudioDevicePropertyScopeOutput;  
thePropertyAddress.mElement = kAudioObjectPropertyElementMaster; 
// see if the device supports volume control, if so, then get it 
if (AudioObjectHasProperty(_targetDevice, &thePropertyAddress)) { 
    result = AudioObjectGetPropertyData(_targetDevice, &thePropertyAddress, 0, NULL, &thePropSize, &volume); 
    if (result) { cwlog("AudioDeviceManager: Error in AudioObjectGetPropertyData: %d", result); return -1; } 
    gotMaster = YES; 
} else { 
    cwlog("AudioDeviceManager: The target device does not support getting the master volume"); 
} 
// see if the device supports left channel volume control, if so, then get it 
thePropertyAddress.mElement = 1; 
if (AudioObjectHasProperty(_targetDevice, &thePropertyAddress)) { 
    result = AudioObjectGetPropertyData(_targetDevice, &thePropertyAddress, 0, NULL, &thePropSize, &lvolume); 
    if (result) { cwlog("AudioDeviceManager: Error in AudioObjectGetPropertyData: %d", result); return -1; } 
    gotLeft = YES; 
} else { 
    cwlog("AudioDeviceManager: The target device does not support getting the left channel volume"); 
} 
thePropertyAddress.mElement = 2; 
// see if the device supports right channel volume control, if so, then get it 
if (AudioObjectHasProperty(_targetDevice, &thePropertyAddress)) { 
    result = AudioObjectGetPropertyData(_targetDevice, &thePropertyAddress, 0, NULL, &thePropSize, &rvolume); 
    if (result) { cwlog("AudioDeviceManager: Error in AudioObjectGetPropertyData: %d", result); return -1; } 
    gotRight = YES; 
} else { 
    // if the device does not support master volume control, do nothing 
    cwlog("AudioDeviceManager: The target device does not support getting the right channel volume"); 
} 
if(!gotMaster && !gotLeft && !gotRight) { 
    cwlog("AudioDeviceManager: Could not get any volume settings for %s (%u)", [[self nameOfDevice:_targetDevice] UTF8String], _targetDevice); 
    return -1; 
}