Windows Media Video 7/8 Encoder

Artikel
03/22/2021

The Windows Media Video 7/8 encoder implements previous versions of the Windows Media Video encoder.

Class Identifier

The class identifier (CLSID) for the Windows Media Video 7/8 encoder is CLSID_CWMVXEncMediaObject. You can create an instance of the encoder by calling CoCreateInstance.

Interfaces

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

Operating system	Encoder behavior
Windows XP	A Windows Media video encoder always behaves as a DMO.
Windows Vista and Windows 7	By default, a Windows Media video encoder behaves as a DMO. If you obtain an IMFTransform interface on a video encoder, it behaves as an MFT.

Input Formats

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

MEDIASUBTYPE_IYUV
MEDIASUBTYPE_I420
MEDIASUBTYPE_YV12
MEDIASUBTYPE_NV11
MEDIASUBTYPE_NV12
MEDIASUBTYPE_YUY2
MEDIASUBTYPE_UYVY
MEDIASUBTYPE_YVYU
MEDIASUBTYPE_RGB32
MEDIASUBTYPE_RGB24
MEDIASUBTYPE_RGB565
MEDIASUBTYPE_RGB555
MEDIASUBTYPE_RGB8
MEDIASUBTYPE_PHOTOMOTION

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

MFVideoFormat_IYUV
MFVideoFormat_I420
MFVideoFormat_YV12
MFVideoFormat_NV11
MFVideoFormat_NV12
MFVideoFormat_YUY2
MFVideoFormat_UYVY
MFVideoFormat_YVYU
MFVideoFormat_RGB32
MFVideoFormat_RGB24
MFVideoFormat_RGB565
MFVideoFormat_RGB555
MFVideoFormat_RGB8
MEDIASUBTYPE_PHOTOMOTION

Output Formats

The following table shows the four-character codes (FOURCCs) for the output types supported by the Windows Media Video 7/8 encoder.

Category	FOURCC
Windows Media Video 7	"WMV1"
Windows Media Video 8	"WMV2"

Properties

The Windows Media Video 7/8 encoder supports the following properties.

Property	Description
MFPKEY_ASFOVERHEADPERFRAME	Specifies the overhead, in bytes per packet, required for the container used to store the compressed content. Windows XP and later. Write-only.
MFPKEY_AVGFRAMERATE	Specifies the average frame rate of video content, in frames per second. Windows XP and later. Read-only.
MFPKEY_BAVG	Specifies the buffer window, in milliseconds, of a constrained variable-bit-rate (VBR) stream at its average bit rate (specified by MFPKEY_RAVG). Windows XP and later. Read/write.
MFPKEY_BMAX	Specifies the buffer window, in milliseconds, of a constrained variable-bit-rate (VBR) stream at its peak bit rate (specified by MFPKEY_RMAX). Windows XP and later. Read/write.
MFPKEY_BUFFERFULLNESSINFIRSTBYTE	Specifies whether the encoded video bit stream contains a buffer fullness value with every key frame. Windows XP and later. Read-only.
MFPKEY_CODEDFRAMES	Specifies the number of video frames encoded by the codec. Windows XP and later. Read-only.
MFPKEY_CODEDNONZEROFRAMES	Specifies the number of video frames encoded by the codec that actually contain data. Windows XP and later. Read-only.
MFPKEY_COMPLEXITY	This property is superseded by MFPKEY_COMPLEXITYEX.
MFPKEY_COMPLEXITYEX	Specifies the complexity of the encoder algorithm. Windows Vista and later. Write-only.
MFPKEY_CRISP	Specifies a numeric representation of the tradeoff between motion smoothness and image quality in codec output. Windows XP and later. Write-only.
MFPKEY_DECODERCOMPLEXITYPROFILE	Specifies the device conformance template to which the encoded content conforms. Windows XP and later. Read-only.
MFPKEY_DECODERCOMPLEXITYREQUESTED	Specifies the device conformance template that you want to use for video encoding. Windows XP and later. Write-only.
MFPKEY_DROPPEDFRAMES	Specifies the number of video frames dropped during encoding. Windows XP and later. Read-only.
MFPKEY_ENDOFPASS	Specifies the end of an encoding pass. Windows XP and later. Write-only.
MFPKEY_FOURCC	Specifies the FOURCC that identifies the encoder you want to use. Windows XP and later. Write-only.
MFPKEY_INTERLACEDCODINGENABLED	Specifies whether the codec output will be interlaced. Windows XP and later. Write-only.
MFPKEY_KEYDIST	Specifies the maximum time, in milliseconds, between key frames in the codec output. Windows XP and later. Write-only.
MFPKEY_PASSESRECOMMENDED	Specifies the maximum number of passes supported by the codec. Windows XP and later. Read-only.
MFPKEY_PASSESUSED	Specifies the number of passes that the codec will use to encode the content. Windows XP and later. Read/write.
MFPKEY_PRODUCEDUMMYFRAMES	Specifies whether the encoder produces dummy frame entries in the bit stream for duplicate frames. Windows XP and later. Write-only.
MFPKEY_QPPERFRAME	Specifies QP. Windows Vista and later. Write-only.
MFPKEY_RAVG	Specifies the average bit rate, in bits per second, used for 2-pass variable-bit-rate (VBR) encoding. Windows XP and later. Read/write.
MFPKEY_RMAX	Specifies the peak bit rate, in bits per second, used for constrained 2-pass variable-bit-rate (VBR). Windows XP and later. Read/write.
MFPKEY_TOTALFRAMES	Specifies the number of video frames passed to the encoder during the encoding process. Windows XP and later. Read-only.
MFPKEY_VBRENABLED	Specifies whether the codec will use variable-bit-rate (VBR) encoding. Windows XP and later. Read/write.
MFPKEY_VBRQUALITY	Specifies the actual quality level for quality based (1-pass) variable-bit-rate (VBR) encoding. Windows XP and later. Write-only.
MFPKEY_VIDEOWINDOW	Specifies the amount of content, in milliseconds, that can fit into the model buffer. Windows XP and later. Write-only.
MFPKEY_ZEROBYTEFRAMES	Specifies the number of video frames that were skipped because they were duplicates of previous frames. Windows XP and later. Read-only

Requirements

Requirement	Value
Client	Windows XP, Windows Vista or Windows 7
Header	Wmcodecdsp.h
DLL	Wmvxencd.dll

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