The Windows Media digital signal processors (DSPs) are implemented as COM objects. Each DSP has its own class identifier (CLSID). For example, the Audio Resampler DSP has a CLSID represented by the constant CLSID_CResamplerMediaObject.
Each DSP object exposes the IMediaObject interface so that the object can be used as a DirectX Media Object (DMO) and the IMFTransform interface so that the object can be used as a Media Foundation Transform (MFT).Regardless of whether you use a particular DSP as a DMO or an MFT, you use the same CLSID to create an instance of the DSP . For example, to create an instance of the Color Converter DSP, you use CLSID_CColorConverterDMO , regardless of whether you intend to use the DSP as a DMO or an MFT.
In addition to the core interfaces, each DSP implements the IPropertyStore interface for setting and reading properties.
A Windows Media DSP behaves as a DMO or an MFT depending on which interfaces you obtain and which version of Windows is running. The following table shows the conditions under which a DSP behaves as a DMO or an MFT.
| Operating system | DSP behavior |
| Windows XP | A Windows Media DSP always behaves as a DMO. |
| Windows Vista and Windows 7 | By default, a Windows DSP behaves as a DMO. If you obtain an IMFTransform interface on a DSP, it behaves as an MFT. |
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Build date: 4/7/2010