[英]How to read from - "unsigned char const *" when use Media Foundation?
I have such an implementation我有这样的实现
void coAudioPlayerSampleGrabber::test(SoundDataType dataType,
unsigned char const * pData,
int64_t dataLen)
{
HeapSetInformation(NULL, HeapEnableTerminationOnCorruption, NULL, 0);
IMFSourceReader *pReader = NULL;
IMFByteStream * spByteStream = NULL;
HRESULT hr = S_OK;
// Initialize the COM library.
hr = CoInitializeEx(NULL, COINIT_APARTMENTTHREADED | COINIT_DISABLE_OLE1DDE);
// Initialize the Media Foundation platform.
if (SUCCEEDED(hr))
{
hr = MFStartup(MF_VERSION);
}
hr = MFCreateMFByteStreamOnStreamEx((IUnknown*)pData, &spByteStream);
if (FAILED(hr))
{
printf("Error MFCreateMFByteStreamOnStreamEx");
}
IMFAttributes * Atrr = NULL;
hr = MFCreateAttributes(&Atrr, 10);
if (FAILED(hr))
{
printf("Error MFCreateAttributes");
}
hr = Atrr->SetUINT32(MF_READWRITE_ENABLE_HARDWARE_TRANSFORMS, true);
if (FAILED(hr))
{
printf("Error Atrr->SetUINT32(MF_READWRITE_ENABLE_HARDWARE_TRANSFORMS, true)");
}
hr = MFCreateSourceReaderFromByteStream(spByteStream, Atrr, &pReader);
if (FAILED(hr))
{
printf("Error MFCreateSourceReaderFromByteStream");
}
if (FAILED(hr))
{
printf("Error opening input file");
}
IMFMediaType *pAudioType = NULL; // Represents the PCM audio format.
hr = ConfigureAudioStream(dataType, pReader, &pAudioType);
if (FAILED(hr))
{
printf("Error ConfigureAudioStream");
}
IMFSample *pSample = NULL;
IMFMediaBuffer *pBuffer = NULL;
BYTE *pAudioData = NULL;
DWORD cbBuffer = 0;
std::vector<SampleData> samples_vec;
while (true)
{
DWORD dwFlags = 0;
hr = pReader->ReadSample((DWORD)MF_SOURCE_READER_FIRST_AUDIO_STREAM, 0, NULL, &dwFlags, NULL, &pSample);
if (FAILED(hr)) { break; }
if (dwFlags & MF_SOURCE_READERF_CURRENTMEDIATYPECHANGED)
{
printf("Type change - not supported by WAVE file format.\n");
break;
}
if (dwFlags & MF_SOURCE_READERF_ENDOFSTREAM)
{
printf("End of input file.\n");
break;
}
hr = pSample->ConvertToContiguousBuffer(&pBuffer);
if (FAILED(hr)) { break; }
hr = pBuffer->Lock(&pAudioData, NULL, &cbBuffer);
if (FAILED(hr)) { break; }
//Do something with the pAudioData which is an array of unsigned chars of lenth cbBuffer
SampleData tmp;
tmp.pAudioData = new byte[cbBuffer];
memcpy(tmp.pAudioData, pAudioData, cbBuffer);
tmp.cbBuffer = cbBuffer;
samples_vec.push_back(tmp);
// Unlock the buffer.
hr = pBuffer->Unlock();
pAudioData = NULL;
if (FAILED(hr)) { break; }
}
SafeRelease(&pReader);
SafeRelease(&pSample);
SafeRelease(&pBuffer);
SafeRelease(&spByteStream);
SafeRelease(&Atrr);
// Shut down Media Foundation.
MFShutdown();
CoUninitialize();
}
So as you can see I have pointer to data and size this is actually my data I need to decode it.因此,正如您所看到的,我有指向数据和大小的指针,这实际上是我需要对其进行解码的数据。 Problem is that here问题是这里
hr = MFCreateMFByteStreamOnStreamEx((IUnknown*)pData, &spByteStream);
I got an error access violation
and as far as I see this is because I try to convert pData
to IUnknown*
.我遇到了错误access violation
,据我所知,这是因为我尝试将pData
转换为IUnknown*
。 Question is - How to convert it right?问题是 - 如何正确转换?
You can't cut corners like this:你不能像这样偷工减料:
unsigned char const * pData;
...
hr = MFCreateMFByteStreamOnStreamEx((IUnknown*)pData, &spByteStream);
IUnknown
is not yet another fancy alias for a byte. IUnknown
不是另一个花哨的字节别名。 You are supposed to literally supply interface pointer representing stream, as documented.如文档所述,您应该从字面上提供表示流的接口指针。
Media Foundation does offer you means to read from memory bytes. Media Foundation 确实为您提供了从内存字节读取的方法。 You need to create a create a real stream, IStream
or IRandomAccessStream
or IMFByteStream
per docuemntation.您需要创建一个创建一个真正的流IStream
或IRandomAccessStream
或IMFByteStream
每docuemntation。 Also supply IMFAttributes
you created with proper attributes to specify data type (which otherwise in the case of a file are derived from extension or MIME type) and then Source Reader API would be able to process memory bytes as source of media file data, and suitable decoder would decode audio into PCM data (similar to this ).还为您创建的IMFAttributes
提供适当的属性以指定数据类型(否则在文件的情况下是从扩展名或 MIME 类型派生的),然后 Source Reader API 将能够处理内存字节作为媒体文件数据的源,并且适合解码器将音频解码为 PCM 数据(与此类似)。
Something you can do real quick: CreateStreamOnHGlobal
to create IStream
implementation and copy your bytes into underlying buffer (see docs).您可以快速完成的操作: CreateStreamOnHGlobal
来创建IStream
实现并将您的字节复制到底层缓冲区中(请参阅文档)。 Then MFCreateMFByteStreamOnStream
would create a IMFByteStream
wrappr over it, and you can use this wrapper as MFCreateSourceReaderFromByteStream
argument.然后MFCreateMFByteStreamOnStream
会在它MFCreateMFByteStreamOnStream
创建一个IMFByteStream
wrappr,你可以使用这个包装器作为MFCreateSourceReaderFromByteStream
参数。
I used to use a VectorStream class for such stuff.我曾经为这些东西使用 VectorStream 类。 Some functions are not implemented, but you should get the basic idea.有些功能没有实现,但您应该了解基本概念。
class VectorStream : public IStream
{
public:
bool ReadOnly = false;
ULONG r = 1;
std::vector<char> d;
size_t p = 0;
VectorStream()
{
}
void Clear()
{
d.clear();
p = 0;
}
// IUnknown
virtual HRESULT STDMETHODCALLTYPE QueryInterface(
/* [in] */ REFIID riid,
/* [iid_is][out] */ _COM_Outptr_ void __RPC_FAR* __RPC_FAR* ppvObject)
{
if (riid == __uuidof(IUnknown) || riid == __uuidof(IStream))
{
*ppvObject = (IStream*)this;
r++;
return S_OK;
}
return E_NOINTERFACE;
}
virtual ULONG STDMETHODCALLTYPE AddRef(void)
{
return ++r;
}
virtual ULONG STDMETHODCALLTYPE Release(void)
{
return --r;
}
HRESULT __stdcall Clone(
IStream** ppstm
)
{
return E_NOTIMPL;
}
HRESULT __stdcall Commit(
DWORD grfCommitFlags
)
{
return S_OK;
}
HRESULT __stdcall CopyTo(
IStream* pstm,
ULARGE_INTEGER cb,
ULARGE_INTEGER* pcbRead,
ULARGE_INTEGER* pcbWritten
)
{
return E_NOINTERFACE;
}
HRESULT __stdcall LockRegion(
ULARGE_INTEGER libOffset,
ULARGE_INTEGER cb,
DWORD dwLockType
)
{
return S_OK;
}
HRESULT __stdcall UnlockRegion(
ULARGE_INTEGER libOffset,
ULARGE_INTEGER cb,
DWORD dwLockType
)
{
return S_OK;
}
HRESULT __stdcall Revert()
{
return E_NOTIMPL;
}
HRESULT __stdcall Seek(
LARGE_INTEGER dlibMove,
DWORD dwOrigin,
ULARGE_INTEGER* plibNewPosition
)
{
LARGE_INTEGER lo = { 0 };
if (dwOrigin == STREAM_SEEK_SET)
{
p = dlibMove.QuadPart;
}
if (dwOrigin == STREAM_SEEK_CUR)
{
p += dlibMove.QuadPart;
}
if (dwOrigin == STREAM_SEEK_END)
{
p = d.size() - dlibMove.QuadPart;
}
if (p >= d.size())
p = d.size();
if (plibNewPosition)
plibNewPosition->QuadPart = p;
return S_OK;
}
HRESULT __stdcall SetSize(
ULARGE_INTEGER libNewSize
)
{
d.resize(libNewSize.QuadPart);
return S_OK;
}
int eb = 0;
HRESULT __stdcall Stat(
STATSTG* pstatstg,
DWORD grfStatFlag
)
{
pstatstg->type = STGTY_STREAM;
pstatstg->cbSize.QuadPart = d.size();
pstatstg->grfLocksSupported = true;
return S_OK;
}
unsigned long long readbytes = 0;
HRESULT __stdcall Read(
void* pv,
ULONG cb,
ULONG* pcbRead
)
{
auto av = d.size() - p;
if (cb < av)
av = cb;
memcpy(pv, d.data() + p, av);
p += av;
if (pcbRead)
*pcbRead = (ULONG)av;
// if (av < cb)
// return S_FALSE;
return S_OK;
}
HRESULT __stdcall Write(
const void* pv,
ULONG cb,
ULONG* pcbWritten
)
{
if (ReadOnly)
return STG_E_ACCESSDENIED;
if (d.size() < (p + cb))
{
auto exc = (p + cb) - d.size();
d.resize(d.size() + exc);
}
memcpy(d.data() + p, pv, cb);
p += cb;
if (pcbWritten)
*pcbWritten = cb;
return S_OK;
}
};
It encapsulates std::vector<> in a IStream.它将 std::vector<> 封装在 IStream 中。
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