EWaveError

Declaration

EWaveError = class(Exception)
public
property ErrorCode : MMResult;
property Message: String;
end;

Description

ThbWaveIn and ThbWaveOut are using an exception mechanism to make the application aware of occuring errors. If an error occurs when using a Windows wave function, an EWaveError exception is raised. The ErrorCode property holds the result code of the last executed wave function (MMResult) and then Message property holds the correspondig text.

The playing and recording of waveform-audio data works in an asynchronous mater. Asynchronous occuring errors are advised by triggering an ThbWaveIn.OnWaveError resp. ThbWaveOut.OnWaveError event.

Example

hbWaveOut1.Active := False;
hbWaveOut1.DeviceName := 'Wave Device #1';
hbWaveOut1.Playlist.Clear;
hbWaveOut1.Playlist.Add'('wavefile.wav');
try
  hbWaveOut1.Active := True;
except
  on E:EWaveError do
  begin
    if E.ErrorCode = MMSYSERR_ALLOCATED then
    begin
      MessageDlg('Specified resource is already allocated.', mtInformation, [mbOk], 0);
    end
    else
      raise E;
  end;
end;

The EWaveError class has two properties:

ErrorCode
Message

Value (Hex)	Constant	Description
0	MMSYSERR_NOERROR	no error
MMSYSERR_BASE + 1	MMSYSERR_ERROR	unspecified error
MMSYSERR_BASE + 2	MMSYSERR_BADDEVICEID	device ID out of range
MMSYSERR_BASE + 3	MMSYSERR_NOTENABLED	driver failed enable
MMSYSERR_BASE + 4	MMSYSERR_ALLOCATED	device already allocated
MMSYSERR_BASE + 5	MMSYSERR_INVALHANDLE	device handle is invalid
MMSYSERR_BASE + 6	MMSYSERR_NODRIVER	no device driver present
MMSYSERR_BASE + 7	MMSYSERR_NOMEM	memory allocation error
MMSYSERR_BASE + 8	MMSYSERR_NOTSUPPORTED	function isn't supported
MMSYSERR_BASE + 9	MMSYSERR_BADERRNUM	error value out of range
MMSYSERR_BASE + 10	MMSYSERR_INVALFLAG	invalid flag passed
MMSYSERR_BASE + 11	MMSYSERR_INVALPARAM	invalid parameter passed
MMSYSERR_BASE + 12	MMSYSERR_HANDLEBUSY	handle being used simultaneously on another thread (eg callback)
MMSYSERR_BASE + 13	MMSYSERR_INVALIDALIAS	specified alias not found
MMSYSERR_BASE + 14	MMSYSERR_BADDB	bad registry database
MMSYSERR_BASE + 15	MMSYSERR_KEYNOTFOUND	registry key not found
MMSYSERR_BASE + 16	MMSYSERR_READERROR	registry read error
MMSYSERR_BASE + 17	MMSYSERR_WRITEERROR	registry write error
MMSYSERR_BASE + 18	MMSYSERR_DELETEERROR	registry delete error
MMSYSERR_BASE + 19	MMSYSERR_VALNOTFOUND	registry value not found
MMSYSERR_BASE + 20	MMSYSERR_NODRIVERCB	driver does not call DriverCallback

Message (String)

The Message member holds a text with the description of the occured error. This text can be used to displayed user information and is read from the Windows Multimedia API.

Declaration

Description

See Also

ErrorCode (MMResult)

Message (String)