作为参考,这里是我的程序使用的函数来完成中描述的结果链接问题 https://stackoverflow.com/questions/60445512/how-to-exclude-input-or-output-channels-from-an-aggregate-coreaudio-device:
// Tell CoreAudio which input (or output) streams we actually want to use in our device
// @param devID the CoreAudio audio device ID of the aggregate device to modify
// @param ioProc the rendering callback-function (as was passed to AudioDeviceCreateIOProcID()'s second argument)
// @param scope either kAudioObjectPropertyScopeInput or kAudioObjectPropertyScopeOutput depending on which type of channels we want to modify
// @param numValidChannels how many audio channels in the aggregate device we want to actually use
// @param rightJustify if true, we want to use the last (numValidChannels) in the device; if false we want to use the first (numValidChannels) in the device
// @returns 0 on success or -1 on error
// @note this function doesn't change the layout of the audio-sample data in the audio-render callback; rather it causes some channels of audio in the callback to become zero'd out/unused.
int SetProcStreamUsage(AudioDeviceID devID, void * ioProc, AudioObjectPropertyScope scope, int numValidChannels, bool rightJustify)
{
const AudioObjectPropertyAddress sizesAddress =
{
kAudioDevicePropertyStreamConfiguration,
scope,
kAudioObjectPropertyElementMaster
};
Uint32 streamSizesDataSize = 0;
OSStatus err = AudioObjectGetPropertyDataSize(devID, &sizesAddress, 0, NULL, &streamSizesDataSize);
if (err != noErr)
{
printf("SetProcStreamUsage(%u,%i,%i): AudioObjectGetPropertyDataSize(kAudioDevicePropertyStreamConfiguration) failed!\n", (unsigned int) devID, scope, rightJustify);
return -1; // ("AudioObjectGetPropertyDataSize(kAudioDevicePropertyStreamConfiguration) failed");
}
const AudioObjectPropertyAddress usageAddress =
{
kAudioDevicePropertyIOProcStreamUsage,
scope,
kAudioObjectPropertyElementMaster
};
Uint32 streamUsageDataSize = 0;
err = AudioObjectGetPropertyDataSize(devID, &usageAddress, 0, NULL, &streamUsageDataSize);
if (err != noErr)
{
printf("SetProcStreamUsage(%u,%i,%i): AudioObjectGetPropertyDataSize(kAudioDevicePropertyIOProcStreamUsage) failed!\n", (unsigned int) devID, scope, rightJustify);
return -1; // ("AudioObjectGetPropertyDataSize(kAudioDevicePropertyIOProcStreamUsage) failed");
}
AudioBufferList * bufList = (AudioBufferList*) malloc(streamSizesDataSize); // using malloc() because the object-size is variable
if (bufList)
{
int ret;
err = AudioObjectGetPropertyData(devID, &sizesAddress, 0, NULL, &streamSizesDataSize, bufList);
if (err == noErr)
{
AudioHardwareIOProcStreamUsage * streamUsage = (AudioHardwareIOProcStreamUsage *) malloc(streamUsageDataSize); // using malloc() because the object-size is variable
if (streamUsage)
{
streamUsage->mIOProc = ioProc;
err = AudioObjectGetPropertyData(devID, &usageAddress, 0, NULL, &streamUsageDataSize, streamUsage);
if (err == noErr)
{
if (bufList->mNumberBuffers == streamUsage->mNumberStreams)
{
Int32 numChannelsLeft = numValidChannels;
if (rightJustify)
{
// We only want streams corresponding to the last (N) channels to be enabled
for (Int32 i=streamUsage->mNumberStreams-1; i>=0; i--)
{
streamUsage->mStreamIsOn[i] = (numChannelsLeft > 0);
numChannelsLeft -= bufList->mBuffers[i].mNumberChannels;
}
}
else
{
// We only want streams corresponding to the first (N) channels to be enabled
for (Uint32 i=0; i<streamUsage->mNumberStreams; i++)
{
streamUsage->mStreamIsOn[i] = (numChannelsLeft > 0);
numChannelsLeft -= bufList->mBuffers[i].mNumberChannels;
}
}
// Now set the stream-usage per our update, above
err = AudioObjectSetPropertyData(devID, &usageAddress, 0, NULL, streamUsageDataSize, streamUsage);
if (err != noErr)
{
printf("SetProcStreamUsage(%u,%i,%i): AudioObjectSetPropertyData(kAudioDevicePropertyIOProcStreamUsage) failed!\n", (unsigned int) devID, scope, rightJustify);
ret = -1; // ("AudioObjectSetPropertyData(kAudioDevicePropertyIOProcStreamUsage) failed");
}
}
else
{
printf("SetProcStreamUsage(%u,%i,%i): #Buffers (%u) doesn't match #Streams (%u)!\n", (unsigned int) devID, scope, rightJustify, bufList->mNumberBuffers, streamUsage->mNumberStreams);
ret = -1;
}
}
else
{
printf("SetProcStreamUsage(%u,%i,%i): AudioObjectSetPropertyData(kAudioDevicePropertyIOProcStreamUsage) failed!\n", (unsigned int) devID, scope, rightJustify);
ret = -1; // ("AudioObjectGetPropertyData(kAudioDevicePropertyIOProcStreamUsage) failed");
}
free(streamUsage);
}
else ret = -1; // out of memory?
}
else
{
printf("SetProcStreamUsage(%u,%i,%i): AudioObjectGetPropertyData(kAudioDevicePropertyStreamConfiguration) failed!\n", (unsigned int) devID, scope, rightJustify);
ret = -1; // ("AudioObjectGetPropertyData(kAudioDevicePropertyStreamConfiguration) failed");
}
free(bufList);
return ret;
}
else return -1; // out of memory?
}