你用了iFilterGraph吗?如果用了iFilterGraph,当存在OverlayMixer时,可以参考IMixerPinConfig2的用法
procedure TMainForm.Button1Click(Sender: TObject);
var
DDS: IBaseFilter;
MixerPinConfig2: IMixerPinConfig2;
inPIN: IPin;
Tmp: TDDColorControl;
begin
DDS := GetFilter(FilterGraph.FFilterGraph, CLSID_OverlayMixer);
GetPin(DDS, inPIN, PINDIR_INPUT, 1);
if inPIN <> nil then
inPIN.QueryInterface(IID_IMixerPinConfig2, MixerPinConfig2);
if MixerPinConfig2 <> nil then
begin
ZeroMemory(@Tmp, SizeOf(TDDColorControl));
Tmp.dwSize := SizeOf(TDDCOLORCONTROL);
MixerPinConfig2.GetOverlaySurfaceColorControls(Tmp);
Tmp.lBrightness := 6000;
MixerPinConfig2.setOverlaySurfaceColorControls(Pointer(@Tmp));
end;
end;