操作 Wave 文件(15): 合并与剪裁 wav 文件

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

uses MMSystem;

//从指定 wav 文件中获取格式信息和波形数据的函数
function GetWaveFmtData(const path: string; var fmt: TWaveFormatEx; var buf: TBytes): Boolean;
var
  hFile: HMMIO;
  ckiRIFF,ckiFmt,ckiData: TMMCKInfo;
begin
  Result := False;
  hFile := mmioOpen(PChar(path), nil, MMIO_READ);
  if hFile = 0 then Exit;
  ZeroMemory(@ckiRIFF, SizeOf(TMMCKInfo));
  ZeroMemory(@ckiFmt, SizeOf(TMMCKInfo));
  ZeroMemory(@ckiData, SizeOf(TMMCKInfo));
  ckiRIFF.fccType := mmioStringToFOURCC('WAVE', 0);
  ckiFmt.ckid := mmioStringToFOURCC('fmt', 0);
  ckiData.ckid := mmioStringToFOURCC('data', 0);
  ZeroMemory(@fmt, SizeOf(TWaveFormatEx));
  mmioDescend(hFile, @ckiRIFF, nil, MMIO_FINDRIFF);
  if (ckiRIFF.ckid = FOURCC_RIFF) and (ckiRIFF.fccType = mmioStringToFOURCC('WAVE',0)) and
     (mmioDescend(hFile, @ckiFmt, @ckiRIFF, MMIO_FINDCHUNK) = MMSYSERR_NOERROR) and
     (mmioRead(hFile, @fmt, ckiFmt.cksize) = ckiFmt.cksize) and
     (mmioAscend(hFile, @ckiFmt, 0) = MMSYSERR_NOERROR) and
     (mmioDescend(hFile, @ckiData, @ckiRIFF, MMIO_FINDCHUNK) = MMSYSERR_NOERROR) then
  begin
    SetLength(buf, ckiData.cksize);
    Result := (mmioRead(hFile, PAnsiChar(buf), ckiData.cksize) = ckiData.cksize);
  end;
  mmioClose(hFile, 0);
end;

//根据格式信息和波形数据建立 wav 文件的函数
function CreateWave(const path: string; const fmt: TWaveFormatEx; const buf: TBytes): Boolean;
var
  h: HMMIO;
  ckiRiff, ckiFmt, ckiData: TMMCKInfo;
begin
  ZeroMemory(@ckiRiff, SizeOf(TMMCKInfo));
  ckiRiff.cksize := 44 - 8 + Length(buf);
  ckiRiff.fccType := mmioStringToFOURCC('WAVE', 0);

  ZeroMemory(@ckiFmt, SizeOf(TMMCKInfo));
  ckiFmt.ckid := mmioStringToFOURCC('fmt', 0);

  ZeroMemory(@ckiData, SizeOf(TMMCKInfo));
  ckiData.ckid := mmioStringToFOURCC('data', 0);
  ckiData.cksize := Length(buf);

  h := mmioOpen(PChar(path), nil, MMIO_CREATE or MMIO_WRITE);
  if (h <> 0) and (mmioCreateChunk(h, @ckiRiff, MMIO_CREATERIFF) = MMSYSERR_NOERROR) and
    (mmioCreateChunk(h, @ckiFmt, 0) = MMSYSERR_NOERROR) and
    (mmioWrite(h, PAnsiChar(@fmt), SizeOf(TPCMWaveFormat)) = SizeOf(TPCMWaveFormat)) and
    (mmioAscend(h, @ckiFmt, 0) = MMSYSERR_NOERROR) and
    (mmioCreateChunk(h, @ckiData, 0) = MMSYSERR_NOERROR) then
    Result := (mmioWrite(h, PAnsiChar(buf), Length(buf)) = Length(buf));
  mmioClose(h, 0);
end;


//截取 wav 文件, 本例截留了文件的 1/4
procedure TForm1.Button1Click(Sender: TObject);
const
  pathSource = 'C:\WINDOWS\Media\Windows XP 启动.wav';
  pathDest = 'C:\Temp\New1.wav';
var
  fmt: TWaveFormatEx;
  buf: TBytes;
begin
  GetWaveFmtData(pathSource, fmt, buf);
  SetLength(buf, Length(buf) div 4);
  CreateWave(pathDest, fmt, buf);
end;

//合并 wav 文件
procedure TForm1.Button2Click(Sender: TObject);
const
  path1 = 'C:\WINDOWS\Media\Windows XP 启动.wav';
  path2 = 'C:\WINDOWS\Media\Windows XP 关机.wav';
  pathDest = 'C:\Temp\New2.wav';
var
  fmt1,fmt2: TWaveFormatEx;
  buf1,buf2: TBytes;
  oldLen: Integer;
begin
  GetWaveFmtData(path1, fmt1, buf1);
  GetWaveFmtData(path2, fmt2, buf2);

  if CompareMem(@fmt1, @fmt2, SizeOf(TWaveFormatEx)) then
  begin
    oldLen := Length(buf1);
    SetLength(buf1, Length(buf1) + Length(buf2));
    CopyMemory(@buf1[oldLen], Pointer(buf2), Length(buf2));
    CreateWave(pathDest, fmt1, buf1);
  end else ShowMessage('文件格式不一致, 没有执行合并!');
end;

end.