c++ - 从 IStream 读取到缓冲区(音频)

Question

我基本上是在尝试将音频流的内容读入 char * 缓冲区以应用 FFT。我正在使用 SAPI 来简化应用 FFT 后需要进行的转换。

我在 HGLOBAL 上分配了一个 IStream 缓冲区

// Address of IStream* pointer variable that receives the interface pointer to the new stream object.
CComPtr<IStream> pMemStream;
// A memory handle allocated by the GlobalAlloc function, or if NULL a new handle is to be allocated instead.
HGLOBAL hGlobal = GlobalAlloc(GMEM_MOVEABLE, sizeof(pMemStream));
// Create stream object that uses an HGLOBAL memory handle to store the stream contents.
hr = ::CreateStreamOnHGlobal(hGlobal, TRUE, &pMemStream);

然后我将wav内容写入这个流

// Variable to receive ISpStream pointer
CComPtr<ISpStream> cpSpStream;
hr = cpSpStream.CoCreateInstance(CLSID_SpStream);
hr = cpSpStream->SetBaseStream(pMemStream, SPDFID_WaveFormatEx, defaultStreamFormat.WaveFormatExPtr());
hr = cpVoice->SetOutput(cpSpStream, TRUE);
hr = cpVoice->Speak(L"This is a phrase.", SPF_DEFAULT, NULL);

我可以通过说出流来验证流是否包含 wav 内容:

// Speak the modified stream.
cpVoice->SetOutput(NULL, FALSE);
cpVoice->SpeakStream(cpSpStream, SPF_DEFAULT, NULL);

但是，当我尝试获取流的缓冲区时，我只读取了垃圾数据(缓冲区中的所有“=”)。

IStream *pIstream;
cpSpStream->GetBaseStream(&pIstream);
STATSTG stats;
pIstream->Stat(&stats, STATFLAG_NONAME);
ULONG sSize = stats.cbSize.QuadPart;
ULONG bytesRead;
char *pBuffer = new char[sSize];
pIstream->Read(pBuffer, sSize, &bytesRead);

我做错了什么？这让我抓狂。谢谢，-弗朗西斯科

Answer 1

SAPI 写入流后，流位置在末尾，因此 IStream::Read 会将其“读取”输出设置为零字节。

在从流中读取之前，调用 IStream::Seek(zero, STREAM_SEEK_SET, NULL) 并且您将能够读取数据。