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AMVAUncompBufferInfo structure (amva.h)

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[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 It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation.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.]

The AMVAUncompBufferInfo structure describes the uncompressed surfaces to be allocated by the video renderer.

Syntax

typedef struct _tag_AMVAUncompBufferInfo {
  DWORD         dwMinNumSurfaces;
  DWORD         dwMaxNumSurfaces;
  DDPIXELFORMAT ddUncompPixelFormat;
} AMVAUncompBufferInfo, *LPAMVAUncompBufferInfo;

Members

dwMinNumSurfaces

Minimum number of surfaces to allocate.

dwMaxNumSurfaces

Maximum number of surfaces to allocate.

ddUncompPixelFormat

DDPIXELFORMAT structure, describing the pixel format of the allocated surfaces.

Remarks

The VMR-7 and VMR-9 filters allocate at least dwMinNumSurfaces surfaces. For interlaced content, the VMR-7 allocates additional surfaces equal to the number of forward and backward reference frames required by the deinterlacer. The VMR-7 gets these values by calling IVMRDeinterlaceControl::GetDeinterlaceModeCaps. The VMR-9 does not need to allocate additional surfaces for deinterlacing. Thus:

  • For the VMR-7, the number of allocated surfaces is dwMinNumSurfaces + dwNumForwardRefSamples + dwNumBackwardRefSamples. For progressive content, the last two values will be zero.
  • For the VMR-9, the number of allocated surfaces is dwMinNumSurfaces.
Initially, the decoder should set dwMinNumSurfaces equal to the optimal number of surfaces needed to decode smoothly. If the renderer cannot allocate that many surfaces, the connection will fail with the error code E_OUTOFMEMORY. The decoder should reconnect with the same media type but set dwMinNumSurfaces equal to the minimum number of surfaces required for decoding. For example, the optimal number of surfaces might be 8, while the minimum is 4.

Requirements

Requirement Value
Minimum supported client Windows 2000 Professional [desktop apps only]
Minimum supported server Windows 2000 Server [desktop apps only]
Header amva.h (include Videoacc.h)

See also

DirectShow Structures

IAMVideoAcceleratorNotify::GetUncompSurfacesInfo