Windows Media Video 9 Decoder

The Windows Media Video 9 decoder decodes video streams that were encoded by the Windows Media Video Encoder. The encoder and decoder support the following four categories of encoded video.

  • Windows Media Video 9 Simple Profile
  • Windows Media Video 9 Main Profile
  • Windows Media Video 9 Advanced Profile
  • Windows Media Video 9.1 Image

Class Identifier

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

Interfaces

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

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

 

Beginning with Windows 7, the Windows Media Video decoder implements the IDMOQualityControl interface.

Input Formats

The following table shows the four-character codes (FOURCCs) that correspond to the categories of encoded input that are supported by the Windows Media Video decoder.

CategoryFOURCC
Windows Media Video 9 Simple Profile"WMV3"
Windows Media Video 9 Main Profile"WMV3"
Windows Media Video 9 Advanced Profile"WVC1"
Windows Media Video 9.1 Image"WMVP" for 9.1, "WVP2" for 9.1 version 2

 

Output Formats

The Windows Media Video decoder supports the following output media subtypes when it is acting as a DMO.

  • MEDIASUBTYPE_NV12
  • MEDIASUBTYPE_YV12
  • MEDIASUBTYPE_YUY2
  • MEDIASUBTYPE_UYVY
  • MEDIASUBTYPE_YVYU
  • MEDIASUBTYPE_NV11
  • MEDIASUBTYPE_RGB32
  • MEDIASUBTYPE_RGB24
  • MEDIASUBTYPE_RGB565
  • MEDIASUBTYPE_RGB555
  • MEDIASUBTYPE_RGB8

The Windows Media Video decoder supports the following output media subtypes when it is acting as an MFT.

  • MFVideoFormat_NV12
  • MFVideoFormat_YV12
  • MFVideoFormat_YUY2
  • MFVideoFormat_UYVY
  • MFVideoFormat_YVYU
  • MFVideoFormat_NV11
  • MFVideoFormat_RGB32
  • MFVideoFormat_RGB24
  • MFVideoFormat_RGB565
  • MFVideoFormat_RGB555
  • MFVideoFormat_RGB8

Properties

The Windows Media Video decoder supports the following properties.

Property Description
MFPKEY_DECODER_DEINTERLACING

Specifies whether the codec decodes interlaced video frames from the compressed stream as progressive frames.

Windows XP and later.
Simple Profile, Main Profile, Advanced Profile.
Read/write.
MFPKEY_DXVA_ENABLED

Specifies whether the decoder will use DirectX video acceleration hardware, if available.

Windows XP and later.
Simple Profile, Main Profile, Advanced Profile.
Write-only.
MFPKEY_AVDecVideoSWPowerLevel

Specifies the power level for the decoder.

Windows 7.
Simple Profile, Main Profile, Advanced Profile, Image.
Read/write.
MFPKEY_FI_ENABLED

Specifies whether the decoder should use frame interpolation.

Windows XP and later.
Simple Profile, Main Profile, Advanced Profile, Image.
Write-only.
MFPKEY_FI_SUPPORTED

Specifies whether the decoder supports frame interpolation.

Windows XP and later.
Simple Profile, Main Profile, Advanced Profile, Image
Read-only.
MFPKEY_NUMTHREADSDEC

Specifies the number of threads that the decoder will use.

Windows Vista and later.
Simple Profile, Main Profile, Advanced Profile, Image.
Read/write.
MFPKEY_POSTPROCESSMODE

Specifies the post processing mode for the decoder.

Windows Vista and later.
Simple Profile, Main Profile, Advanced Profile, Image.
Write-only.
g_wszWMVCNeedsDrain

Specifies whether the decoder should be drained.

Windows 8
Read-only.

This property is used by the Windows Media Format runtime. The property type is VARIANT_BOOL. If the value is VARIANT_TRUE, the decoder should be drained after a discontinuity. For more information about draining an MFT, see Basic MFT Processing Model.

Note  To query this property, use the IPropertyBag interface.

 

Remarks

The maximum resolution allowed by the Windows Media Video 9 decoder is 4096x4096.

Requirements

Client

Windows XP, Windows Vista, or Windows 7

Header

Wmcodecdsp.h

DLL

Wmvdecod.dll

See also

Codec Objects
Codec Implementation

 

 

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