IWMReaderCallback::OnSample 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 It has been superseded by Source Reader and Sink Writer.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 OnSample method is called during the reading of a file (due to a Start call) indicating that new data is available.

Syntax

HRESULT OnSample(
  [in] DWORD      dwOutputNum,
  [in] QWORD      cnsSampleTime,
  [in] QWORD      cnsSampleDuration,
  [in] DWORD      dwFlags,
  [in] INSSBuffer *pSample,
  [in] void       *pvContext
);

Parameters

[in] dwOutputNum

DWORD containing the number of the output to which the sample belongs.

[in] cnsSampleTime

QWORD containing the sample time, in 100-nanosecond units.

[in] cnsSampleDuration

QWORD containing the sample duration, in 100-nanosecond units. For video streams, if the SampleDuration data unit extension was set on this sample when the file was created, then this parameter will contain that value. For more information on SampleDuration , see INSSBuffer3::GetProperty.

[in] dwFlags

The flags that can be specified in dwFlags have the following uses.

[in] pSample

Pointer to the INSSBuffer interface of an object containing the sample. The reader calls SAFE_RELEASE on this pointer after your OnSample method returns. You can call AddRef on this pointer if you need to keep a reference count on the buffer. Do not call Release on this pointer unless you have called AddRef.

[in] pvContext

Generic pointer, for use by the application. This pointer is the context pointer given to the IWMReader::Start method.

Return value

To use this method, you must implement it in your application. The method should always return S_OK.

Remarks

This method is for receipt of uncompressed samples by output number only. If you need to receive samples for multiple streams in a single output (as in the case of mutually exclusive streams), you must use IWMReaderCallbackAdvanced::OnStreamSample. In this case, you will receive compressed samples. There is no way to use the reader to receive uncompressed samples by stream number.

Requirements

See also

IWMReaderCallback Interface