static unsafe void DeriveBufferSize(AudioStreamBasicDescription *ASBDesc, int maxPacketSize, double seconds, int *outBufferSize, int *outNumPacketsToRead)
{
const int maxBufferSize = 0x10000;
const int minBufferSize = 0x4000;
if (ASBDesc->FramesPerPacket != 0)
{
double numPacketsForTime = ASBDesc->SampleRate / ASBDesc->FramesPerPacket * seconds;
* outBufferSize = (int)(numPacketsForTime * maxPacketSize);
}
else
{
*outBufferSize = maxBufferSize > maxPacketSize ? maxBufferSize : maxPacketSize;
}
if (*outBufferSize > maxBufferSize &&
*outBufferSize > maxPacketSize)
{
*outBufferSize = maxBufferSize;
}
else
{
if (*outBufferSize < minBufferSize)
{
*outBufferSize = minBufferSize;
}
}
*outNumPacketsToRead = *outBufferSize / maxPacketSize;
}
private static unsafe void CreateQueue(AudioStream *pThis)
{
int dataFormatSize = sizeof(AudioStreamBasicDescription);
AudioStreamBasicDescription *pDataFormat = &pThis->DataFormat;
OSStatus status = API.AudioFileGetProperty(pThis->AudioFile, AudioFileProperty.DataFormat, &dataFormatSize, pDataFormat);
API.CheckStatus(status);
status = API.AudioQueueNewOutput(pDataFormat, OnReadBuffer, pThis, null, null, 0, &pThis->Queue);
API.CheckStatus(status);
dataFormatSize = sizeof(int);
int *pMaxPacketSize = &pThis->MaxPacketSize;
status = API.AudioFileGetProperty(pThis->AudioFile, AudioFileProperty.PacketSizeUpperBound, &dataFormatSize, pMaxPacketSize);
API.CheckStatus(status);
DeriveBufferSize(&pThis->DataFormat, pThis->MaxPacketSize, 0.5, &pThis->BufferByteSize, &pThis->NumPacketsToRead);
}
extern static int AudioFileGetGlobalInfo(AudioFileGlobalProperty propertyID, uint size, ref AudioFileTypeAndFormatID inSpecifier, ref uint ioDataSize, AudioStreamBasicDescription *outPropertyData);
public static extern unsafe OSStatus AudioQueueNewOutput(AudioStreamBasicDescription *pFormat, AudioQueueOutputCallback callback, void *pUserData, void *runLoop, void *pRunLoopMode, uint flags, AudioQueue **pQueue);
