IDirectDrawMediaStream::GetFormat method (ddstream.h)

Articolo
4/26/2023

[The feature associated with this page, DirectShow, is a legacy feature. It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation. Those features have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use MediaPlayer, IMFMediaEngine and Audio/Video Capture in Media Foundation instead of DirectShow, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]

Note This interface is deprecated. New applications should not use it.

Retrieves the current media stream's format and, optionally, its desired format.

Syntax

HRESULT GetFormat(
  [out] DDSURFACEDESC      *pDDSDCurrent,
  [out] IDirectDrawPalette **ppDirectDrawPalette,
  [out] DDSURFACEDESC      *pDDSDDesired,
  [out] DWORD              *pdwFlags
);

Parameters

[out] pDDSDCurrent

Pointer to a DirectDraw surface description that will contain the current media stream's format.

[out] ppDirectDrawPalette

Address of a pointer to an IDirectDrawPalette interface if one exists.

[out] pDDSDDesired

Pointer to a DirectDraw surface description that will contain the current media stream's desired format.

[out] pdwFlags

Pointer to the flags set in a DDSURFACEDESC structure. Flags of interest include:

Flag	Description
DDSD_CAPS	Indicates that the surface capability member of the structure is valid.
DDSD_HEIGHT	Indicates that the height member of the structure is valid.
DDSD_PIXELFORMAT	Indicates that the pixel format member of the structure is valid.
DDSD_WIDTH	Indicates that the width member of the structure is valid.

Return value

Returns one of the following values.

Return code	Description
DDERR_INVALIDPARAMS	One of the DirectDraw surface parameters is invalid.
E_POINTER	One or more of the required parameters is invalid.
S_OK	Success.

Remarks

After you call this method, you can either conform to the current format or attempt to change the format by calling the IDirectDrawMediaStream::SetFormat method.

All of this method's parameters are optional; set any of them to NULL to indicate that you don't want to retrieve that information.

To perform a progressive render, create a single sample and repeatedly use that sample for successive frames of video. Video decompressors use this technique to do partial updates to the previous frame.

You must initialize the dwSize member of the DDSURFACEDESC structure before calling this method.

The DDSD_CAPS flag will return one of the values listed in the DDSCAPS structure or DDSCAPS_DATAEXCHANGE, which is defined as DDSCAPS_SYSTEMMEMORY|DDSCAPS_VIDEOMEMORY in Ddrawex.h.

Requirements

Requirement	Value
Target Platform	Windows
Header	ddstream.h

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