Microsoft DirectX 8.0

DMO Wrapper Filter

The DMO Wrapper filter enables a Microsoft® DirectShow® application to use a Microsoft® DirectX® Media Object (DMO) within a filter graph. The filter wraps the DMO and handles all the details of using the DMO, such as passing data to and from the DMO. Also, the filter aggregates the DMO, so the application can query the filter for any COM interfaces that the DMO exposes.

For information on using this filter, see Using DMOs in a DirectShow Application.

Filter Interfaces IBaseFilter, IDMOWrapperFilter, IPersistStream
Input Pin Media Types See Remarks
Input Pin Interfaces IMemInputPin, IPin, IQualityControl
Output Pin Media Types See Remarks
Output Pin Interfaces IAMStreamConfig, IAMVideoCompression, IPin, IQualityControl
Filter CLSID CLSID_DMOWrapperFilter
Property Page CLSID No property page
Executable Qasf.dll
Merit See Remarks
Category See Remarks

Remarks

For each input stream on the DMO, the filter creates a corresponding input pin. For each output stream, it creates a corresponding output pin. The media types depend on the DMO.

If the DMO is a video encoder or an audio encoder, the filter's output pin exposes the IAMStreamConfig interface. If the DMO is a video encoder, the output pin also exposes the IAMVideoCompression interface. The pin queries the DMO for the interface; if the DMO supports the interface, the pin delegates to the DMO. Otherwise, the pin provides its own implementation.

DirectShow assigns all DMOs a default merit value of MERIT_NORMAL + 0x800. This value falls between MERIT_NORMAL and MERIT_PREFERRED. Decoder filters generally have a merit value of MERIT_NORMAL. Therefore, the filter graph manager will usually select a DMO decoder over a decoder filter. To override the default merit value, add a registry entry to the DMO's registry key in HKEY_CLASSES_ROOT\CLSID. Include a DWORD value named Merit whose value specifies the merit.

The DMO Wrapper filter does not appear by itself in any category. When it wraps a DMO, it appears in the DirectShow category that corresponds to the DMO's category, under the name of the DMO. For more information, see Using DMOs in a DirectShow Application.