How to use the TMediaPlayer to record sound from a microphone

Problem/Question/Abstract:

I'm trying to use MediaPlayer to record sound into a wave file through a microphone. Can someone show me some simple code to do the recording?

Answer:

The TMediaPlayer can only open a wave file that has at least one byte of data in it. I found this out when I tried to create and open a wave file that was nothing but a wave header. The TMediaPlayer wouldn't do it. The following code creates a wave file with a single byte of data at the beginning. It is a bit of a kludge to do it this way, but it works. You need to add MMSYSTEM to the uses clause of any unit that uses this function.


function CreateNewWave(NewFileName: string): Boolean;
var
  DeviceID: Word;
  Return: LongInt;
  MciOpen: TMCI_Open_Parms;
  MciRecord: TMCI_Record_Parms;
  MciPlay: TMCI_Play_Parms;
  MciSave: TMCI_SaveParms;
  MCIResult: LongInt;
  Flags: Word;
  TempFileName: array[0..255] of char;
begin
  MediaPlayer.Close;
  StrPCopy(TempFileName, NewFileName);
  MciOpen.lpstrDeviceType := 'waveaudio';
  MciOpen.lpstrElementName := '';
  Flags := Mci_Open_Element or Mci_Open_Type;
  MCIResult := MciSendCommand(0, MCI_OPEN, Flags, LongInt(@MciOpen));
  DeviceID := MciOpen.wDeviceId;
  MciRecord.dwTo := 1;
  Flags := Mci_To or Mci_Wait;
  MCIResult := MciSendCommand(DeviceID, Mci_Record, Flags, LongInt(@MciRecord));
  mciPlay.dwFrom := 0;
  Flags := Mci_From or Mci_Wait;
  MciSendCommand(DeviceId, Mci_Play, Flags, LongInt(@MciPlay));
  mciSave.lpfileName := TempFilename;
  Flags := MCI_Save_File or Mci_Wait;
  MCIResult := MciSendCommand(DeviceID, MCI_Save, Flags, LongInt(@MciSave));
  Result := MciSendCommand(DeviceID, Mci_Close, 0, LongInt(nil)) = 0;
end;