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4/8/2010

The Video/Image Compression Manager is a wrapper filter for installable decompressors that support the Video Compression Manager (VCM) interface. The VCM interface is not a part of the DirectShow architecture, so a wrapper filter is required to enable these compressors to function in the context of a filter graph.

When the Filter Graph Manager is building a graph to render an AVI file, it checks the FOURCC in the file's AVI header to determine whether the video stream is compressed.

If it is, the Filter Graph Manager adds the AVI decompressor, which then searches the registry for an installed decompressor that can handle the file. All this happens automatically; your application is not responsible for these details.

The following table shows the filter properties.

Filter property Description

Filter Interfaces

IBaseFilter Interface

Input Pin Media Types and Sub Types

MEDIATYPE_Video, MEDIASUBTYPE_NULL, FORMAT_VideoInfo. The subtype must correspond to an old-style FOURCC.

Input Pin Interfaces

IMemInputPin Interface, IPin Interface, IQualityControl Interface

Output Pin Media Types

MEDIATYPE_Video, MEDIASUBTYPE_NULL, FORMAT_VideoInfo

Output Pin Interfaces

IMediaPosition Interface, IMediaSeeking Interface, IPin, IQualityControl

Filter CLSID

CLSID_AVIDec

Property Page CLSID

No property page.

Executable

Quartz.dll

Merit

MERIT_NORMAL

Filter Categories

CLSID_LegacyAmFilterCategory

Remarks

The media subtype on the pins is built from the FourCC code in the AVI file.

See Also