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Windows Media MPEG4 V1/V2 Decoder

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The Windows Media MPEG4 V1/V2 decoder decodes MPEG4 V1/V2 video streams.

Class Identifier

The class identifier (CLSID) for the Windows Media MPEG4 V1/V2 decoder is represented by the constant CLSID_CMpeg4DecMediaObject. You can create an instance of the MPEG4 V1/V2 decoder by calling CoCreateInstance.

Formats

The Windows Media MPEG4 V1/V2 decoder supports the following input media types.

  • MEDIASUBTYPE_MPG4
  • MEDIASUBTYPE_mpg4
  • MEDIASUBTYPE_MP42
  • MEDIASUBTYPE_mp42

The Windows Media MPEG4 V1/V2 decoder supports the following output media subtypes when it is acting as a DirectX Media Object (DMO).

  • MEDIASUBTYPE_YUY2
  • MEDIASUBTYPE_UYVY
  • MEDIASUBTYPE_RGB32
  • MEDIASUBTYPE_RGB24
  • MEDIASUBTYPE_RGB565
  • MEDIASUBTYPE_RGB8
  • MEDIASUBTYPE_RGB555

The Windows Media MPEG4 V1/V2 decoder supports the following output media subtypes when it is acting as a Media Foundation Transform (MFT).

  • MFVideoFormat_YUY2
  • MFVideoFormat_UYVY
  • MFVideoFormat_RGB32
  • MFVideoFormat_RGB24
  • MFVideoFormat_RGB565
  • MFVideoFormat_RGB8
  • MFVideoFormat_RGB555

Remarks

The Windows Media MPEG4 V1/V2 decoder object exposes the IMediaObject interface so that the object can be used as a DirectX Media Object (DMO), and it exposes the IMFTransform interface so that the object can be used as a Media Foundation Transform (MFT). The object has the same class identifier (CLSID) regardless of whether it acts as a DMO or an MFT.

An MPEG4 V1/V2 decoder 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 an MPEG4 V1/V2 decoder behaves as a DMO or an MFT.

Operating system Decoder behavior
Windows XP An MPEG4 V1/V2 decoder always behaves as a DMO.
Windows Vista and Windows 7 By default, an MPEG4 V1/V2 decoder behaves as a DMO. If you obtain an Video Subtype GUIDs interface on an MPEG4 V1/V2 decoder, it behaves as an MFT.

 

The globally unique identifiers (GUIDs) for RGB media subtypes differ depending on whether a decoder is acting as a DMO or an MFT. The GUIDs for non-RGB media subtypes are the same, regardless of whether a decoder is acting as a DMO or an MFT. For information about the GUIDs that represent video subtypes, see Video Subtype GUIDs.

Requirements

Requirement Value
Minimum supported client
 Windows XP [desktop apps only]
Minimum supported server
 Windows Server 2003 [desktop apps only]
Header
Wmcodecdsp.h
DLL
MPG4DECD.dll

See also

Codec Objects