What does the InputSize field mean in VIDEO_STREAM_CONFIG_CAPS?

Question

Quoted from here:

Size of the incoming signal, expressed through the Win32 SIZE structure as the image rectangle's width and height in pixels.

For a compressor, the size is taken from the width and height members of the Win32 BITMAPINFOHEADER structure in the input pin's AM_MEDIA_TYPE structure.

For a capture filter, the size is the largest signal the filter can digitize with every pixel remaining unique.

typedef struct  _VIDEO_STREAM_CONFIG_CAPS
{
  GUID guid;
  ULONG VideoStandard;
  SIZE InputSize;
  SIZE MinCroppingSize;
  SIZE MaxCroppingSize;
  int CropGranularityX;
  int CropGranularityY;
  int CropAlignX;
  int CropAlignY;
  SIZE MinOutputSize;
  SIZE MaxOutputSize;
  int OutputGranularityX;
  int OutputGranularityY;
  int StretchTapsX;
  int StretchTapsY;
  int ShrinkTapsX;
  int ShrinkTapsY;
  LONGLONG MinFrameInterval;
  LONGLONG MaxFrameInterval;
  LONG MinBitsPerSecond;
  LONG MaxBitsPerSecond;
}  VIDEO_STREAM_CONFIG_CAPS;

What does it mean by For a capture filter, the size is the largest signal the filter can digitize with every pixel remaining unique.,can anyone help?

Answer 1

I guess this means camera's native resolution. If some camera can capture 640x480 image but can provide 1280x960 image, each real pixel will be repeated by upscaling and represented by 4 image pixels, it won't be unique.