IMediaPosition::get_PrerollTime method (control.h)
[The feature associated with this page, DirectShow, is a legacy feature. It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation. Those features have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use MediaPlayer, IMFMediaEngine and Audio/Video Capture in Media Foundation instead of DirectShow, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]
The get_PrerollTime method retrieves the amount of data that will be queued before the start position.
Syntax
HRESULT get_PrerollTime(
[out] REFTIME *pllTime
);
Parameters
[out] pllTime
Pointer to a variable that receives the preroll time, in seconds.
Return value
Returns an HRESULT value. Possible values include the following.
| Return code | Description |
|---|---|
|
Success. |
|
Not implemented. |
|
NULL pointer argument. |
Remarks
The preroll is the time prior to the start position at which nonrandom access devices, such as tape players, should start rolling.
If no filter in the graph implements this method, the Filter Graph Manager sets the value of *pllTime to zero and returns S_OK.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows 2000 Professional [desktop apps only] |
| Minimum supported server | Windows 2000 Server [desktop apps only] |
| Target Platform | Windows |
| Header | control.h (include Dshow.h) |
| Library | Strmiids.lib |