如何调节左右声道？(50分)

如何调节左右声道？
1)请问如何用Delphi自带控件：MediaPlayer 转换声道？
我用控件MediaPlayer 编了一个程序播放VCD，但不能
转换声道，2)用此构件如何控制CD音频,我想单击一个按
钮转到第7首歌, 请大侠指点小弟迷津！
谢谢！

柳枫

const
MCI_SETAUDIO= $873;
MCI_DGV_SETAUDIO_SOURCE_LEFT=1;
MCI_DGV_SETAUDIO_SOURCE_STEREO=0;
MCI_DGV_SETAUDIO_SOURCE_RIGHT=2;
MCI_DGV_SETAUDIO_SOURCE=$4004;
MCI_DGV_SETAUDIO_VALUE=$01000000;
MCI_DGV_SETAUDIO_ITEM=$00800000;

type MCI_DGV_SETAUDIO_PARMS=record
dwCallbackWORD;
dwItemWORD;
dwValueWORD;
dwOverWORD;
lpstrAlgorithmChar;
lpstrQualityChar;
end
//立体声
procedure Tmainfrm.sdchange;
var
s: MCI_DGV_SETAUDIO_PARMS
begin

mciSendCommand(mplayer.DeviceID,MCI_SETAUDIO,MCI_SET_OFF,integer(@s));
s.dwValue:=MCI_DGV_SETAUDIO_SOURCE_STEREO;

s.dwItem:=MCI_DGV_SETAUDIO_SOURCE;
mciSendCommand(mplayer.DeviceID,MCI_SETAUDIO, MCI_DGV_SETAUDIO_VALUE or MCI_DGV_SETAUDIO_ITEM ,integer(@s));
mciSendCommand(mplayer.DeviceID,MCI_SETAUDIO, MCI_SET_ON,integer(@s));
end;

//左声道
procedure Tmainfrm.sdchangel;
var
s: MCI_DGV_SETAUDIO_PARMS
begin

mciSendCommand(mplayer.DeviceID,MCI_SETAUDIO,MCI_SET_OFF,integer(@s));
s.dwValue:=MCI_DGV_SETAUDIO_SOURCE_LEFT;

s.dwItem:=MCI_DGV_SETAUDIO_SOURCE;
mciSendCommand(mplayer.DeviceID,MCI_SETAUDIO, MCI_DGV_SETAUDIO_VALUE or MCI_DGV_SETAUDIO_ITEM ,integer(@s));
mciSendCommand(mplayer.DeviceID,MCI_SETAUDIO, MCI_SET_ON,integer(@s));
end;

//右声道
procedure Tmainfrm.sdchanger;
var
s: MCI_DGV_SETAUDIO_PARMS
begin

mciSendCommand(mplayer.DeviceID,MCI_SETAUDIO,MCI_SET_OFF,integer(@s));
s.dwValue:=MCI_DGV_SETAUDIO_SOURCE_RIGHT;

s.dwItem:=MCI_DGV_SETAUDIO_SOURCE;
mciSendCommand(mplayer.DeviceID,MCI_SETAUDIO, MCI_DGV_SETAUDIO_VALUE or MCI_DGV_SETAUDIO_ITEM ,integer(@s));
mciSendCommand(mplayer.DeviceID,MCI_SETAUDIO, MCI_SET_ON,integer(@s));
end;

唔该晒！！！！

接受答案了.