操作 Wave 文件(10): 输入输出设备与格式支持

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    ListBox1: TListBox;
    ListBox2: TListBox;
    Button1: TButton;
    Button2: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

uses MMSystem;

//设备列表; 指定设备时经常使用 WAVE_MAPPER 参数, 这样会自动选用合适的设备.
procedure TForm1.Button1Click(Sender: TObject);
var
  i: Integer;
  waveOutCaps: TWaveOutCaps;
  waveInCaps: TWaveInCaps;
begin
  ListBox1.Items.Add('音频输出设备列表:');
  for i := 0 to waveOutGetNumDevs do
  begin
    ZeroMemory(@waveOutCaps, SizeOf(TWaveOutCaps));
    waveOutGetDevCaps(i, @waveOutCaps, SizeOf(TWaveOutCaps));
    ListBox1.Items.Add(waveOutCaps.szPname);
  end;

  ListBox2.Items.Add('音频输入设备列表:');
  for i := 0 to waveInGetNumDevs do
  begin
    ZeroMemory(@waveInCaps, SizeOf(TWaveInCaps));
    waveOutGetDevCaps(i, @waveInCaps, SizeOf(TWaveInCaps));
    ListBox2.Items.Add(waveInCaps.szPname);
  end;
end;

//判断是否支持指定的 Wave 格式
procedure TForm1.Button2Click(Sender: TObject);
var
  fmt: TPCMWaveFormat;
begin
  fmt.wf.wFormatTag := WAVE_FORMAT_PCM;
  fmt.wf.nChannels := 2;
  fmt.wf.nSamplesPerSec := 22050;
  fmt.wf.nAvgBytesPerSec := 88200;
  fmt.wf.nBlockAlign := 4;
  fmt.wBitsPerSample := 16;

  if waveOutOpen(nil, 0, PWaveFormatEx(@fmt), 0, 0, WAVE_FORMAT_QUERY) = 0 then
    ShowMessage('第一个输出设备支持此格式');

  if waveInOpen(nil, 0, PWaveFormatEx(@fmt), 0, 0, WAVE_FORMAT_QUERY) = 0 then
    ShowMessage('第一个输入设备支持此格式');
end;

end.

有把格式支持的判断写成函数的, 如:

---

function IsFormatSupported(fmt: Pointer; DeviceId: DWORD): Boolean;
begin
  Result := (waveOutOpen(nil, DeviceId, PWaveFormatEx(fmt), 0, 0, WAVE_FORMAT_QUERY) = 0);
end;