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IAMDroppedFrames Interface

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Microsoft DirectShow 9.0

IAMDroppedFrames Interface

The IAMDroppedFrames interface retrieves performance information from a video capture filter, including how many frames were dropped and how many were delivered. Applications can use this interface to determine capture performance at run-time.

In addition to the methods inherited from IUnknown, the IAMDroppedFrames interface exposes the following methods.

Method Description
GetAverageFrameSize Retrieves the average size of the frames that the filter has captured.
GetDroppedInfo Retrieves an array of frame numbers that were dropped.
GetNumDropped Retrieves the total number of frames that the filter has dropped since it started streaming. 
GetNumNotDropped Retrieves the total number of frames that the filter has delivered since it started streaming.

Remarks

Some filters that expose this interface do not implement the GetDroppedInfo or GetAverageFrameSize method.

For Windows Driver Model (WDM) devices, the WDM Video Capture Filter automatically exposes this interface if the WDM driver supports the PROPSETID_VIDCAP_DROPPEDFRAMES property set. For more information, see the Windows DDK documenation.

The number of dropped frames is reported by the capture driver. This information is not directly correlated with any particular media sample, so it is not accurate on a per-frame basis, although it should be accurate over time.

Requirements

Header: Declared in Strmif.h; include Dshow.h.

Library: Use Strmiids.lib.