IAsyncReader::SyncReadAligned method (strmif.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 It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation.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 SyncReadAligned method performs a synchronous read. The method blocks until the request is completed. The file positions and the buffer address must be aligned; check the allocator properties for the required alignment.
Syntax
HRESULT SyncReadAligned(
IMediaSample *pSample
);
Parameters
pSample
Pointer to the IMediaSample interface of a media sample provided by the caller.
Return value
Returns an HRESULT value. Possible values include the following.
| Return code | Description |
|---|---|
|
Invalid alignment. |
|
Retrieved fewer bytes than requested. (Probably the end of the file was reached.) |
|
Success. |
Remarks
Before calling this method, retrieve a media sample from the pin's allocator. Time stamp the sample with the byte offsets you are requesting, first and last inclusive, multiplied by 10,000,000. Byte offsets are relative to the start of the stream.
The start and stop positions should match the alignment that was decided when the pins connected. Otherwise, the method returns VFW_E_BADALIGN. If the agreed alignment is coarser than the actual alignment of the stream, the stop position might exceed the real duration. If so, the method rounds the stop position down to the actual alignment.
This method performs an unbuffered read, so it might be faster than the IAsyncReader::SyncRead method.
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 | strmif.h (include Dshow.h) |
| Library | Strmiids.lib |