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IltmmSampleSource::GetSampleBuffer

Summary

Retrieves an unused sample buffer.

Syntax

#include "ltmm.h"

Language	Syntax
C	HRESULT IltmmSampleSource_getSampleBuffer(pSampleSource, TimeOut, MediaSample)
C++	HRESULT GetSampleBuffer(TimeOut, MediaSample)

Parameters

IltmmSampleSource *pSampleSource

Pointer to an IltmmSampleSource interface that references the sample source object that is getting the sample buffer.

long TimeOut

Maximum time to wait for a free sample buffer, in milliseconds.

IltmmMediaSampleDisp **MediaSample

Pointer to a variable to be updated with a pointer to an IltmmMediaSampleDisp interface. This interface references the new media sample buffer.

Returns

Value	Meaning
S_OK	The function was successful.
<> S_OK	An error occurred. Refer to the Error Codes or the HRESULT error codes in the DirectShow documentation.

Comments

The buffer retrieved by this function comes from a pool of buffers. There should be no assumptions made on the number of available buffers. If you get a buffer, fill it with data and then deliver it downstream, you should release the buffer before getting another. This is because there may only be one buffer available at a time.

If the Function succeeds, the caller must free the interface referenced by the MediaSample parameter by calling the interface's Release Function. Failure to release the buffer could cause further calls to IltmmSampleSource::GetSampleBuffer to fail.

If the function does not retrieve a buffer within the allotted time it will return E_FAIL. If this happens, you may have specified a small timeout and all the available buffers are currently being sent downstream.