IWMSyncReader::SetRangeByFrame 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 It has been superseded by Source Reader and Sink Writer.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 SetRangeByFrame method configures the synchronous reader to read a portion of the file specified by a starting video frame number and a number of frames to read.

Syntax

HRESULT SetRangeByFrame(
  [in] WORD     wStreamNum,
  [in] QWORD    qwFrameNumber,
  [in] LONGLONG cFramesToRead
);

Parameters

[in] wStreamNum

Stream number.

[in] qwFrameNumber

Frame number at which to begin playback. The first frame in a file is number 1.

[in] cFramesToRead

Count of frames to read. Pass 0 to continue playback to the end of the file.

Return value

The method returns an HRESULT. Possible values include, but are not limited to, those in the following table.

Remarks

If the call is successful, all streams are synchronized to the same position based on the presentation time of the selected frame. Subsequent calls to GetNextSample will retrieve samples for all active streams, not just the stream specified in the call to SetRangeByFrame. If you want to receive only samples for a single video stream by frame, you must call SetStreamsSelected and pass the desired stream number prior to calling GetNextSample.

To use SetRangeByFrame, the file in the synchronous reader must be indexed by frame numbers. You can configure the indexer object to index by frame numbers with a call to IWMIndexer2::Configure. Then make a call to IWMIndexer::StartIndexing to index the file with the new settings.

When you set a range for compressed sample delivery using a starting frame number, the synchronous reader will deliver samples starting at the first key frame before the specified frame. If you want to identify the presentation time of a frame, use IWMSyncReader2::SetRangeByFrameEx.

Passing a negative number results in an error.

You can call SetRangeByFrame at any time after a file has been loaded in the synchronous reader.

Requirements

See also

IWMIndexer Interface

IWMSyncReader Interface

IWMSyncReader2::SetRangeByFrameEx

IWMSyncReader::SetRange