Windows Media Video 9 Screen Decoder

The Windows Media Video 9 Screen decoder decodes streams that were encoded by the Windows Media Video 9 Screen Encoder.

Class Identifier

The class identifier (CLSID) for the Windows Media Video 9 Screen decoder is represented by the constant CLSID_CMSSCDecMediaObject. You can create an instance of the decoder by calling CoCreateInstance.

Input Types

The four-character code (FOURCC) for Windows Media Video Screen Version 9 encoded content is "MSS2".

The following input types are supported by the Version 9 Screen decoder.

  • MEDIASUBTYPE_MSS2

Output Types

The following output types are supported by the Version 9 Screen decoder when it is being used as a DirectX Media Object (DMO).

  • MEDIASUBTYPE_RGB24
  • MEDIASUBTYPE_RGB32
  • MEDIASUBTYPE_ARGB32
  • MEDIASUBTYPE_RGB565
  • MEDIASUBTYPE_RGB555
  • MEDIASUBTYPE_RGB8

The following output types are supported by the Version 9 Screen decoder when it is being used as a Media Foundation Transform (MFT).

  • MFVideoFormat_RGB24
  • MFVideoFormat_RGB32
  • MFVideoFormat_ARGB32
  • MFVideoFormat_RGB565
  • MFVideoFormat_RGB555
  • MFVideoFormat_RGB8

Remarks

A screen 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).

A screen 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 a screen decoder behaves as a DMO or an MFT.

Operating system Decoder behavior
Windows XPA Windows Media Screen decoder always behaves as a DMO.
Windows Vista and Windows 7By default, a Windows Media Screen decoder behaves as a DMO. If you obtain an IMFTransform interface on a screen decoder, it behaves as an MFT.

 

You can use the same CLSID (CLSID_CMSSCDecMediaObject) to create the Version 7 Screen decoder and the Version 9 Screen decoder. The FOURCC for Windows Media Video Screen Version 7 encoded content is "MSS1". The Version 7 Screen decoder supports the MEDIASUBTYPE_MSS1 input type.

Requirements

Client

Windows XP, Windows Vista, or Windows 7

Header

Wmcodecdsp.h

DLL

Wmvsdecd.dll

See also

Codec Objects
Codec Implementation
Using the Windows Media Video 9 Screen Codec
Windows Media Video 9 Screen Encoder

 

 

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