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Windows Media MPEG4 V1/V2 Decoder

  • Article

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 IMFTransform 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 media subtypes, see Media Subtype GUIDs.

Requirements

Minimum supported client

 Windows XP

Minimum supported server

 Windows Server 2003

Header

 Wmcodecdsp.h

DLL

 MPG4DECD.dll

See Also

Codec Objects

 

 

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Build date: 4/7/2010