IMFSourceResolver::BeginCreateObjectFromURL Method

Artikel
07/27/2011

Begins an asynchronous request to create a media source or a byte stream from a URL.

Syntax

HRESULT BeginCreateObjectFromURL(
  [in]   LPCWSTR pwszURL,
  [in]   DWORD dwFlags,
  [in]   IPropertyStore *pProps,
  [out]  IUnknown **ppIUnknownCancelCookie,
  [in]   IMFAsyncCallback *pCallback,
  [in]   IUnknown *punkState
);

Parameter

pwszURL [in]
Null-terminated string that contains the URL to resolve.
dwFlags [in]
Bitwise OR of flags. See Source Resolver Flags.
pProps [in]
Pointer to the IPropertyStore interface of a property store. The method passes the property store to the scheme handler or byte-stream handler that creates the object. The handler can use the property store to configure the object. This parameter can be NULL. For more information, see Configuring a Media Source.
ppIUnknownCancelCookie [out]
Receives an IUnknown pointer or the value NULL. If the value is not NULL, you can cancel the asynchronous operation by passing this pointer to the IMFSourceResolver::CancelObjectCreation method. The caller must release the interface. This parameter can be NULL.
pCallback [in]
Pointer to the IMFAsyncCallback interface of a callback object. The caller must implement this interface.
punkState [in]
Pointer to the IUnknown interface of a state object, defined by the caller. This parameter can be NULL. You can use this object to hold state information. The object is returned to the caller when the callback is invoked.

Rückgabewert

The method returns an HRESULT. Possible values include, but are not limited to, those in the following table.

Rückgabecode	Beschreibung
S_OK	The method succeeded.
MF_E_SOURCERESOLVER_MUTUALLY_EXCLUSIVE_FLAGS	The dwFlags parameter contains mutually exclusive flags.
MF_E_UNSUPPORTED_SCHEME	The URL scheme is not supported.

Hinweise

The dwFlags parameter must contain either the MF_RESOLUTION_MEDIASOURCE flag or the MF_RESOLUTION_BYTESTREAM flag, but should not contain both.

For local files, you can pass the file name in the pwszURL parameter; the file: scheme is not required.

When the operation completes, the source resolver calls the IMFAsyncCallback::Invoke method. The Invoke method should call IMFSourceResolver::EndCreateObjectFromURL to get a pointer to the object that was created.

The usage of the pProps parameter depends on the implementation of the media source.

Anforderungen

Mindestens unterstützter Client	Windows Vista
Mindestens unterstützter Server	Windows Server 2008
Header	Mfidl.h
Bibliothek	Mfuuid.lib

Siehe auch

IMFSourceResolver

Source Resolver

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