bool CAUOutputDevice::GetPreferredChannelLayout(CCoreAudioChannelLayout& layout)
{
if (!m_DeviceId)
return false;
UInt32 propertySize = 0;
Boolean writable = false;
OSStatus ret = AudioDeviceGetPropertyInfo(m_DeviceId, 0, false,
kAudioDevicePropertyPreferredChannelLayout, &propertySize, &writable);
if (ret)
return false;
void* pBuf = malloc(propertySize);
ret = AudioDeviceGetProperty(m_DeviceId, 0, false,
kAudioDevicePropertyPreferredChannelLayout, &propertySize, pBuf);
if (ret)
CLog::Log(LOGERROR, "CAUOutputDevice::GetPreferredChannelLayout: "
"Unable to retrieve preferred channel layout. Error = %s", GetError(ret).c_str());
else
{
// Copy the result into the caller's instance
layout.CopyLayout(*((AudioChannelLayout*)pBuf));
}
free(pBuf);
return (ret == noErr);
}
bool CCoreAudioDevice::GetPreferredChannelLayout(CCoreAudioChannelLayout& layout) const
{
if (!m_DeviceId)
return false;
AudioObjectPropertyAddress propertyAddress;
propertyAddress.mScope = kAudioDevicePropertyScopeOutput;
propertyAddress.mElement = 0;
propertyAddress.mSelector = kAudioDevicePropertyPreferredChannelLayout;
UInt32 propertySize = 0;
OSStatus ret = AudioObjectGetPropertyDataSize(m_DeviceId, &propertyAddress, 0, NULL, &propertySize);
if (ret)
return false;
void* pBuf = malloc(propertySize);
ret = AudioObjectGetPropertyData(m_DeviceId, &propertyAddress, 0, NULL, &propertySize, pBuf);
if (ret != noErr)
CLog::Log(LOGERROR, "CCoreAudioDevice::GetPreferredChannelLayout: "
"Unable to retrieve preferred channel layout. Error = %s", GetError(ret).c_str());
else
{
// Copy the result into the caller's instance
layout.CopyLayout(*((AudioChannelLayout*)pBuf));
}
free(pBuf);
return (ret == noErr);
}
bool CCoreAudioDevice::GetPreferredChannelLayoutForStereo(CCoreAudioChannelLayout &layout) const
{
if (!m_DeviceId)
return false;
AudioObjectPropertyAddress propertyAddress;
propertyAddress.mScope = kAudioDevicePropertyScopeOutput;
propertyAddress.mElement = 0;
propertyAddress.mSelector = kAudioDevicePropertyPreferredChannelsForStereo;
UInt32 channels[2];// this will receive the channel labels
UInt32 propertySize = sizeof(channels);
OSStatus ret = AudioObjectGetPropertyData(m_DeviceId, &propertyAddress, 0, NULL, &propertySize, &channels);
if (ret != noErr)
CLog::Log(LOGERROR, "CCoreAudioDevice::GetPreferredChannelLayoutForStereo: "
"Unable to retrieve preferred channel layout. Error = %s", GetError(ret).c_str());
else
{
// Copy/generate a layout into the result into the caller's instance
layout.CopyLayoutForStereo(channels);
}
return (ret == noErr);
}
//Note: in multichannel mode CA will either pull 2 channels of data (stereo) or 6/8 channels of data
//(every speaker setup with more then 2 speakers). The difference between the number of real speakers
//and 6/8 channels needs to be padded with unknown channels so that the sample size fits 6/8 channels
//
//device [in] - the device whose channel layout should be used
//channelMap [in/out] - if filled it will it indicates that we are called from initialize and we log the requested map, out returns the channelMap for device
//channelsPerFrame [in] - the number of channels this device is configured to (e.x. 2 or 6/8)
void AEDeviceEnumerationOSX::GetAEChannelMap(CAEChannelInfo &channelMap, unsigned int channelsPerFrame) const
{
CCoreAudioChannelLayout calayout;
bool logMapping = channelMap.Count() > 0; // only log if the engine requests a layout during init
bool mapAvailable = false;
unsigned int numberChannelsInDeviceLayout = CA_MAX_CHANNELS; // default number of channels from CAChannelMap
AudioChannelLayout *layout = NULL;
// try to fetch either the multichannel or the stereo channel layout from the device
if (channelsPerFrame == 2 || channelMap.Count() == 2)
mapAvailable = m_caDevice.GetPreferredChannelLayoutForStereo(calayout);
else
mapAvailable = m_caDevice.GetPreferredChannelLayout(calayout);
// if a map was fetched - check if it is usable
if (mapAvailable)
{
layout = calayout;
if (layout == NULL || layout->mChannelLayoutTag != kAudioChannelLayoutTag_UseChannelDescriptions)
mapAvailable = false;// wrong map format
else
numberChannelsInDeviceLayout = layout->mNumberChannelDescriptions;
}
// start the mapping action
// the number of channels to be added to the outgoing channelmap
// this is CA_MAX_CHANNELS at max and might be lower for some output devices (channelsPerFrame)
unsigned int numChannelsToMap = std::min((unsigned int)CA_MAX_CHANNELS, (unsigned int)channelsPerFrame);
// if there was a map fetched we force the number of
// channels to map to channelsPerFrame (this allows mapping
// of more then CA_MAX_CHANNELS if needed)
if (mapAvailable)
numChannelsToMap = channelsPerFrame;
std::string layoutStr;
if (logMapping)
{
CLog::Log(LOGDEBUG, "%s Engine requests layout %s", __FUNCTION__, ((std::string)channelMap).c_str());
if (mapAvailable)
CLog::Log(LOGDEBUG, "%s trying to map to %s layout: %s", __FUNCTION__, channelsPerFrame == 2 ? "stereo" : "multichannel", calayout.ChannelLayoutToString(*layout, layoutStr));
else
CLog::Log(LOGDEBUG, "%s no map available - using static multichannel map layout", __FUNCTION__);
}
channelMap.Reset();// start with an empty map
for (unsigned int channel = 0; channel < numChannelsToMap; channel++)
{
// we only try to map channels which are defined in the device layout
enum AEChannel currentChannel;
if (channel < numberChannelsInDeviceLayout)
{
// get the channel from the fetched map
if (mapAvailable)
currentChannel = caChannelToAEChannel(layout->mChannelDescriptions[channel].mChannelLabel);
else// get the channel from the default map
currentChannel = CAChannelMap[channel];
}
else// fill with unknown channels
currentChannel = caChannelToAEChannel(kAudioChannelLabel_Unknown);
if(!channelMap.HasChannel(currentChannel))// only add if not already added
channelMap += currentChannel;
}
if (logMapping)
CLog::Log(LOGDEBUG, "%s mapped channels to layout %s", __FUNCTION__, ((std::string)channelMap).c_str());
}