IWMReader::Open method (wmsdkidl.h)
[The feature associated with this page, Windows Media Format 11 SDK, is a legacy feature. It has been superseded by Source Reader and Sink Writer. Source Reader and Sink Writer have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use Source Reader and Sink Writer instead of Windows Media Format 11 SDK, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]
The Open method opens an ASF file for reading.
Syntax
HRESULT Open(
[in] const WCHAR *pwszURL,
[in] IWMReaderCallback *pCallback,
[in] void *pvContext
);
Parameters
[in] pwszURL
Pointer to a wide-character null-terminated string containing the path and name of the file to be opened. This method accepts a path to a folder on a local machine, a path to a network share, or a uniform resource locator (URL).
[in] pCallback
Pointer to the object that implements the IWMReaderCallback interface.
[in] pvContext
Generic pointer, for use by the application. This is passed to the application in calls to OnStatus.
Return value
The method returns an HRESULT. Possible values include, but are not limited to, those in the following table.
| Return code | Description |
|---|---|
|
The method succeeded. |
|
The pCallback parameter is NULL. |
|
There is not enough available memory. |
|
The method failed for an unspecified reason. |
Remarks
This method is asynchronous; it returns very quickly and sends a WMT_OPENED status notification to the application's IWMStatusCallback::OnStatus method when the file is opened and ready for use.
Because the method returns before the file is opened, a return value of S_OK does not necessarily mean that the file has been opened successfully. To ascertain the success of the call, you must check the value of the hr parameter of OnStatus when the WMT_OPENED notification is received.
If hr equals NS_E_NO_STREAM it means that the header is not yet available, and that a WMT_SOURCE_SWITCH event will be sent as soon as the header becomes available. No WMT_EOF will be sent before the WMT_SOURCE_SWITCH.
Applications that read files from behind a firewall will have better performance when opening files if the address is specified using the domain name server (DNS) name instead of the IP address.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows 2000 Professional [desktop apps only],Windows Media Format 7 SDK, or later versions of the SDK |
| Minimum supported server | Windows 2000 Server [desktop apps only] |
| Target Platform | Windows |
| Header | wmsdkidl.h (include Wmsdk.h) |
| Library | Wmvcore.lib; WMStubDRM.lib (if you use DRM) |