asked on

Recording/Overwriting Waves with TMediaPlayer

I am using TMediaPlayer to record Wavefiles, and everything works fine except that when the Wavefile already exists, the recording is appended to the original wave rather than overwriting it. Setting StartPos will not work because the recorded sound may be shorter than the original sound, and there would be leftovers at the end of the new recording. I s there an easy solution to this that I'm overlooking? I tried overwriting the wavefile with a zero-length file, but it gives an error (not valid wavefile). Thanks for any help!

ASKER CERTIFIED SOLUTION

inthe

membership

This solution is only available to members.

To access this solution, you must be a member of Experts Exchange.

Start Free Trial

inthe

actually it would be:

if fileexists(MediaPlayer1.Filename)
then deletefile(MediaPlayer1.Filename);

jsexton

ASKER

Barry,

Actually I tried that, but I get an error on open (file does not exist). I tried removing the open statement, but then I get an error on StartRecording (device not open). Here's what I'm trying to do:

WavePlayer.filename := 'c:\my.wav';
DeleteFile(WavePlayer.filename);
WavePlayer.open;

//returns error here (cannot open - does not exist)

WavePlayer.StartRecording;

inthe

ok im going to do a test.

inthe

mmm..ok i see what you eman.
this is because the mediaplayer cant create a new file ...so i went digging sround and found this ,i hop it helps you out.:

This document describes the process for creating added
functionality ,that many Delphi users have requested,
to the TMediaPlayer. The new functionality is the ability
to create a new file with the .wav format when recording.
The procedure "SaveMedia" creates a record type that is
passed to the MCISend command. There is an appexception
that calls close media if any error occurs while attempting
to open the specified file. The application consists two
buttons. Button1 calls the OpenMedia and RecordMedia
procedures in that order.The CloseMedia procedure is called
whenever an exception is generated in this application.
Button2 calls the StopMedia,SaveMedia, and CloseMedia
procedures.

unit utestrec;

interface

uses
Windows, Messages, SysUtils, Classes, Graphics, Controls,
Forms, Dialogs,MPlayer,MMSystem,StdCtrls;

type
TForm1 = class(TForm)
Button1: TButton;
Button2: TButton;
procedure Button1Click(Sender: TObject);
procedure Button2Click(Sender: TObject);
procedure FormCreate(Sender: TObject);
procedure AppException(Sender: TObject; E: Exception);
private
FDeviceID: Word;
{ Private declarations }
public
procedure OpenMedia;
procedure RecordMedia;
procedure StopMedia;
procedure SaveMedia;
procedure CloseMedia;
end;

var
Form1: TForm1;

implementation

{$R *.DFM}

var
MyError,Flags: Longint;

procedure TForm1.OpenMedia;
var
MyOpenParms: TMCI_Open_Parms;
MyPChar: PChar;
TextLen: Longint;
begin
Flags:=mci_Wait or mci_Open_Element or mci_Open_Type;
with MyOpenParms do
begin
dwCallback:=Handle; // TForm1.Handle
lpstrDeviceType:=PChar('WaveAudio');
lpstrElementName:=PChar('');
end;
MyError:=mciSendCommand(0, mci_Open, Flags,
Longint(@MyOpenParms));
if MyError = 0 then
FDeviceID:=MyOpenParms.wDeviceID;
end;

procedure TForm1.RecordMedia;
var
MyRecordParms: TMCI_Record_Parms;
TextLen: Longint;
begin
Flags:=mci_Notify;
with MyRecordParms do
begin
dwCallback:=Handle; // TForm1.Handle
dwFrom:=0;
dwTo:=10000;
end;
MyError:=mciSendCommand(FDeviceID, mci_Record, Flags,
Longint(@MyRecordParms));
end;

procedure TForm1.StopMedia;
var
MyGenParms: TMCI_Generic_Parms;
begin
if FDeviceID <> 0 then
begin
Flags:=mci_Wait;
MyGenParms.dwCallback:=Handle; // TForm1.Handle
MyError:=mciSendCommand(FDeviceID, mci_Stop, Flags,
Longint(@MyGenParms));
end;
end;

procedure TForm1.SaveMedia;
type // not implemented by Delphi
PMCI_Save_Parms = ^TMCI_Save_Parms;
TMCI_Save_Parms = record
dwCallback: DWord;
lpstrFileName: PAnsiChar; // name of file to save
end;
var
MySaveParms: TMCI_Save_Parms;
begin
if FDeviceID <> 0 then
begin
// save the file...
Flags:=mci_Save_File or mci_Wait;
with MySaveParms do
begin
dwCallback:=Handle;
lpstrFileName:=PChar('c:\message.wav');
end;
MyError:=mciSendCommand(FDeviceID, mci_Save, Flags,
Longint(@MySaveParms));
end;
end;

procedure TForm1.CloseMedia;
var
MyGenParms: TMCI_Generic_Parms;
begin
if FDeviceID <> 0 then
begin
Flags:=0;
MyGenParms.dwCallback:=Handle; // TForm1.Handle
MyError:=mciSendCommand(FDeviceID, mci_Close, Flags,
Longint(@MyGenParms));
if MyError = 0 then
FDeviceID:=0;
end;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
OpenMedia;
RecordMedia;
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
StopMedia;
SaveMedia;
CloseMedia;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
Application.OnException := AppException;
end;

procedure TForm1.AppException(Sender: TObject; E: Exception);
begin
CloseMedia;
end;

end.

Regards Barry

jsexton

ASKER

Thanks Barry!

I decided not to use your example code - I'm just going to create a "template" wave file (created in Sound Recorder - just 58 bytes) and copy it for each recording (MediaPlayer just appends the recording to the "empty" wave) - not pretty, but this is just a quick-n-dirty program anyway. Thanks for your help. I'm giving you the points since you took the time to help me out. I'm sure I can use the example in the future.

Cheers!

inthe

OK
Cheers :o)