Digital Signal Processor Implementation
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