Как определить bitrate WAV файла

Delphi , Мультимедиа , Аудио

Автор: http://www.swissdelphicenter.ch

{....}

private
  procedure OpenMedia(WaveFile: string);
  function GetStatus(StatusRequested: DWord): longint;
  procedure CloseMedia;

{....}

var
  MyError, dwFlags: Longint;
  FDeviceID: Word;

{....}

uses
  MMSystem;

{....}

procedure TForm1.OpenMedia(WaveFile: string);
var
  MyOpenParms: TMCI_Open_Parms;
begin
  with MyOpenParms do
  begin
    dwCallback := Handle; // TForm1.Handle
    lpstrDeviceType := PChar('WaveAudio');
    lpstrElementName := PChar(WaveFile);
  end; {with MyOpenParms}
  dwFlags := MCI_WAIT or MCI_OPEN_ELEMENT or MCI_OPEN_TYPE;
  MyError := mciSendCommand(0, MCI_OPEN, dwFlags, Longint(@MyOpenParms));
  // one could use mciSendCommand(DevId, here to specify a particular device
  if MyError = 0 then
    FDeviceID := MyOpenParms.wDeviceID
  else
    raise Exception.Create('Open Failed');
end;

function TForm1.GetStatus(StatusRequested: DWORD): Longint;
var
  MyStatusParms: TMCI_Status_Parms;
begin
  dwFlags := MCI_WAIT or MCI_STATUS_ITEM;
  with MyStatusParms do
  begin
    dwCallback := Handle;
    dwItem := StatusRequested;
  end;
  MyError := mciSendCommand(FDeviceID,
    MCI_STATUS,
    MCI_WAIT or MCI_STATUS_ITEM,
    Longint(@MyStatusParms));
  if MyError = 0 then
    Result := MyStatusParms.dwReturn
  else
    raise Exception.Create('Status call to get status of ' +
      IntToStr(StatusRequested) + ' Failed');
end;

procedure TForm1.CloseMedia;
var
  MyGenParms: TMCI_Generic_Parms;
begin
  if FDeviceID > 0 then
  begin
    dwFlags := 0;
    MyGenParms.dwCallback := Handle; // TForm1.Handle
    MyError := mciSendCommand(FDeviceID, MCI_CLOSE, dwFlags,
      Longint(@MyGenParms));
    if MyError = 0 then
      FDeviceID := 0
    else
    begin
      raise Exception.Create('Close Failed');
    end;
  end;
end;

//Example:
//Beispiel:

procedure TForm1.Button1Click(Sender: TObject);
begin
  if OpenDialog1.Execute then
  begin
    OpenMedia(OpenDialog1.FileName);
    with ListBox1.Items do
    begin
      Add('Average Bytes / Sec : ' +
        IntToStr(GetStatus(MCI_WAVE_STATUS_AVGBYTESPERSEC)));
      Add('Bits / Sample : ' +
        IntToStr(GetStatus(MCI_WAVE_STATUS_BITSPERSAMPLE)));
      Add('Samples / Sec : ' +
        IntToStr(GetStatus(MCI_WAVE_STATUS_SAMPLESPERSEC)));
      Add('Channels : ' + IntToStr(GetStatus(MCI_WAVE_STATUS_CHANNELS)));
    end;
    CloseMedia;
  end;
end;

Статья Как определить bitrate WAV файла раздела Мультимедиа Аудио может быть полезна для разработчиков на Delphi и FreePascal.

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