CVideoTransformFilter class

CVideoTransformFilter Class Hierarchy

The CVideoTransformFilter class is designed primarily as a base class for AVI decompressor filters. This class adds support for quality control to the CTransformFilter class. The filter's Receive method can decide to drop frames, based on quality messages from the renderer and performance measurements that the filter collects while it is streaming.

If the filter drops a frame, it continues to drop frames until it reaches the next key frame. For MPEG streams, the filter does not distinguish between B frames and P frames.

Protected Member Variables Description
m_bQualityChanged Indicates whether the filter has dropped frames.
m_bSkipping Indicates whether the filter is currently dropping frames.
m_itrAvgDecode Average length of time it has taken to decode a frame.
m_itrLate Indicates how late the samples are arriving at the renderer.
m_nFramesSinceKeyFrame The number of frames that the filter has received since the last key frame.
m_nKeyFramePeriod The largest observed interval between key frames.
m_nWaitForKey The current maximum number of delta frames to drop.
m_tDecodeStart Length of time that it took to decode the most recent sample.
Protected Methods Description
AbortPlayback Used to signal a streaming error.
AlterQuality Notifies the filter that a quality change is requested.
Receive Receives a media sample, processes it, and delivers an output sample to the downstream filter.
ShouldSkipFrame Determines whether the filter should drop a specified sample.
StartStreaming Called when the filter switches to the paused state.
Public Methods Description
CVideoTransformFilter Constructor method.
EndFlush Ends a flush operation.

 

 

 

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