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Media Subtype GUIDs

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Each media subtype is identified by a globally unique identifier (GUID). DirectShow and Media Foundation both define a set of constants that represent media subtype GUIDs. MEDIASUBTYPE_RGB32 and MEDIASUBTYPE_IYUV are examples of DirectShow subtype constants. MFVideoFormat_RGB32 and MFVideoFormat_IYUV are examples of Media Foundation subtype constants.

For non-RGB media subtypes, the GUIDs defined by DirectShow match the GUIDs defined by Media Foundation. For example, MEDIASUBTYPE_IYUV from DirectShow and MFVideoFormat_IYUV from Media Foundation both represent the same GUID.

The RGB subtype GUIDs defined by DirectShow do not match the RGB subtype GUIDs defined by Media Foundation. For example, the GUID represented by MEDIASUBTYPE_RGB32 is different from the GUID represented by MFVideoFormat_RGB32.

A Windows Media encoder, decoder, or digital signal processor (DSP) can behave as a DirectX Media Object (DMO) or as a Media Foundation Transform (MFT). When you use a media object as a DMO, and you want to specify an RGB subtype, you must use the subtype GUID defined by DirectShow. When you use a media object as an MFT, and you want to specify an RGB subtype, you must use the subtype GUID defined by Media Foundation.

For information about when a media object behaves as a DMO or an MFT, see Codec Implementation and Digital Signal Processor Implementation.

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