A piece of Delphi code for setting and canceling windows mute Effect

Seeing perfect mm asking for such a DOS command in windows, I found no, so I excerpted the following code and compiled a console program.

Unit unit1;
Interface
Uses mmsystem, dialogs;
Type tdevicename = (master, microphone, waveout, Synth );
Procedure setvolumemute (DN: tdevicename; Value: Boolean );
Implementation
Procedure setvolumemute (DN: tdevicename; Value: Boolean );
VaR
Hmix: hmixer;
Mxlc: mixerlinecontrols;
Mxcd: tmixercontroldetails;
Vol: tmixercontroldetails_unsigned;
Mxc: mixercontrol;
Mxl: tmixerline;
Intret: integer;
Nmixerdevs: integer;
Mcdmute: mixercontroldetails_boolean;
Begin
// Check if mixer is available
Nmixerdevs: = mixergetnumdevs ();
If (nmixerdevs <1) then
Begin
Exit;
End;
// Open the mixer
Intret: = mixeropen (@ hmix, 0, 0, 0, 0 );
If intret = mmsyserr_noerror then
Begin
Case DN
MASTER: mxl. dwcomponenttype: = mixerline_componenttype_dst_speakers;
Microphone:
Mxl. dwcomponenttype: = mixerline_componenttype_src_microphone;
Waveout: mxl. dwcomponenttype: = mixerline_componenttype_src_waveout;
Synth: mxl. dwcomponenttype: = mixerline_componenttype_src_synthesizer;
End;
Mxl. cbstruct: = sizeof (mxl );
// Mixerline info
Intret: = mixergetlineinfo (hmix, @ mxl, mixer_getlineinfof_componenttype );
If intret = mmsyserr_noerror then
Begin
Fillchar (mxlc, sizeof (mxlc), 0 );
Mxlc. cbstruct: = sizeof (mxlc );
Mxlc. dwlineid: = mxl. dwlineid;
Mxlc. dwcontroltype: = mixercontrol_controltype_mute;
Mxlc. ccontrols: = 1;
Mxlc. cbmxctrl: = sizeof (mxc );
Mxlc. pamxctrl: = @ mxc;
// Get the mute Control
Intret: = mixergetlinecontrols (hmix, @ mxlc, mixer_getlinecontrolsf_onebytype );
If intret = mmsyserr_noerror then
Begin
Fillchar (mxcd, sizeof (mxcd), 0 );
Mxcd. cbstruct: = sizeof (tmixercontroldetails );
Mxcd. dwcontrolid: = mxc. dwcontrolid;
Mxcd. cchannels: = 1;
Mxcd. cbdetails: = sizeof (mixercontroldetails_boolean );
Mxcd. padetails: = @ mcdmute;
// Set and unset mute
Mcdmute. fvalue: = ord (value );
Intret: = mixersetcontroldetails (hmix, @ mxcd, mixer_setcontroldetailsf_value );
If intret <> mmsyserr_noerror then
Showmessage ('setcontroldetails error ');
End
Else
Showmessage ('getlineinfo error ');
End;
Intret: = mixerclose (hmix );
End;
End;
End.