[转贴]用LabWindows/CVI制作的音频播放器

lgh269

大家都知道，MP3、MID、WAV、WMA等格式的音频文件可以通过调用底层函数来实现播放的！
　　在这里，我介绍利用自己编制的音频解码器来播放音乐的例子，其中，已经将解码器封装到了动态库里，只给出了接口函数及调用规则！

动态库头文件为：

//打开音频文件  pathname为文件路径名
int __stdcall opensong (char *pathname);
//播放音频文件  position为播放的起始位置
int __stdcall playsong (char *pathname, int position);
//暂停播放
int __stdcall pausesong (char *pathname);
//停止播放，并关闭设备
int __stdcall stopsong (char *pathname);
//播放状态　kind  0:所播放文件的长度　　1：播放状态，为"playing,pause,stoped"等　　2：播放的进度，以毫秒计
int __stdcall statussong (char *pathname, int kind, char *status);
//关于对话框
void about(void);


　　应用程序界面为：
本帖包含图片:




程序代码为：

#include
#include
#include
#include "exe.h"
#include "mci.h"
static char pathname[MAX_PATHNAME_LEN];
static int panelHandle;
int __stdcall WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
                      LPSTR lpszCmdLine, int nCmdShow)
{
if (InitCVIRTE (hInstance, 0, 0) == 0)
  return -1; /* out of memory */
if ((panelHandle = LoadPanel (0, "exe.uir", PANEL)) < 0)
  return -1;
DisplayPanel (panelHandle);
RunUserInterface ();
DiscardPanel (panelHandle);
return 0;
}
int CVICALLBACK OkCallback (int panel, int control, int event,
  void *callbackData, int eventData1, int eventData2)
{
int status;
char mode[128];
switch (event)
{
  case EVENT_COMMIT:
  status = FileSelectPopup ("", "*.mp3", "*.mp3;*.wav;*.mid;*.wma", "打开音频文件", VAL_OK_BUTTON, 0, 0, 1, 1, pathname);
  opensong(pathname);
  playsong(pathname, 0);
  statussong(pathname, 1, mode);
  SetCtrlVal (panelHandle, PANEL_STRING, mode);
  break;
}
return 0;
}
int CVICALLBACK QuitCallback (int panel, int control, int event,
  void *callbackData, int eventData1, int eventData2)
{
switch (event)
{
  case EVENT_COMMIT:
  QuitUserInterface (0);
  break;
}
return 0;
}
int CVICALLBACK stop (int panel, int control, int event,
  void *callbackData, int eventData1, int eventData2)
{
char status[128];
switch (event)
{
  case EVENT_COMMIT:
  stopsong(pathname);
  statussong(pathname, 1, status);
  SetCtrlVal (panelHandle, PANEL_STRING, status);
  break;
}
return 0;
}
int CVICALLBACK pause (int panel, int control, int event,
  void *callbackData, int eventData1, int eventData2)
{
char status[128];
switch (event)
{
  case EVENT_COMMIT:
  pausesong(pathname);
  statussong(pathname, 1, status);
  SetCtrlVal (panelHandle, PANEL_STRING, status);
  break;
}
return 0;
}
int CVICALLBACK continu (int panel, int control, int event,
  void *callbackData, int eventData1, int eventData2)
{
char status[128];
int position = 0;
switch (event)
{
  case EVENT_COMMIT:
  status[0] = '\0';
  statussong(pathname, 2, status);
  Fmt(&position, "%i<%s", status);
  playsong(pathname, position);

  status[0] = '\0';
  statussong(pathname, 1, status);
  SetCtrlVal (panelHandle, PANEL_STRING, status);
  break;
}
return 0;
}
int CVICALLBACK pre (int panel, int control, int event,
  void *callbackData, int eventData1, int eventData2)
{
char status[128];
int position;
switch (event)
{
  case EVENT_COMMIT:
  statussong(pathname, 1, status);
  SetCtrlVal (panelHandle, PANEL_STRING, status);
  statussong(pathname, 2, status);
  Fmt (&position, "%i<%s", status);
  position += 5000;
  playsong(pathname, position);
  break;
}
return 0;
}
int CVICALLBACK back (int panel, int control, int event,
  void *callbackData, int eventData1, int eventData2)
{
char status[128];
int position;
switch (event)
{
  case EVENT_COMMIT:
  statussong(pathname, 1, status);
  SetCtrlVal (panelHandle, PANEL_STRING, status);
  statussong(pathname, 2, status);
  Fmt (&position, "%i<%s", status);
  position -= 5000;
  playsong(pathname, position);
  break;
}
return 0;
}
int CVICALLBACK len (int panel, int control, int event,
  void *callbackData, int eventData1, int eventData2)
{
char status[128];
switch (event)
{
  case EVENT_COMMIT:
  statussong(pathname, 0, status);
  SetCtrlVal (panelHandle, PANEL_STRING, status);
  break;
}
return 0;
}
int CVICALLBACK aboutme (int panel, int control, int event,
  void *callbackData, int eventData1, int eventData2)
{
switch (event)
{
  case EVENT_COMMIT:
  about();
  break;
}
return 0;
}
在LabWindows/CVI下制作的动态链接库一般情况下是可以用在其它语言中的，我在这里简单介绍一下用法！

首先，声明外部模块：

Declare Function opensong& Lib "mci.dll" (ByVal x1$)
Declare Function playsong& Lib "mci.dll" (ByVal x1$, ByVal x2&)
Declare Function pausesong& Lib "mci.dll" (ByVal x1$)
Declare Function stopsong& Lib "mci.dll" (ByVal x1$)
Declare Function statussong& Lib "mci.dll" (ByVal x1$, ByVal x2&, ByVal x3$)
Declare Function about& Lib "mci.dll" ()

然后制作界面：
本帖包含图片:



然后写入代码：

Dim x As Integer
Dim status As String * 128
Private Sub Command1_Click()
opensong ("c:\1.mp3")
x = playsong("c:\1.mp3", 0)
x = statussong("c:\1.mp3", 1, status)
Text1.Text = status
End Sub
Private Sub Command2_Click()
x = stopsong("c:\1.mp3")
x = statussong("c:\1.mp3", 1, status)
Text1.Text = status
End Sub
Private Sub Command3_Click()
x = pausesong("c:\1.mp3")
x = statussong("c:\1.mp3", 1, status)
Text1.Text = status
End Sub
Private Sub Command4_Click()
x = statussong("c:\1.mp3", 2, status)
x = playsong("c:\1.mp3", Val(status))
x = statussong("c:\1.mp3", 1, status)
Text1.Text = status
End Sub
Private Sub Command5_Click()
x = statussong("c:\1.mp3", 2, status)
x = playsong("c:\1.mp3", Val(status) + 5000)
x = statussong("c:\1.mp3", 1, status)
Text1.Text = status
End Sub
Private Sub Command6_Click()
x = statussong("c:\1.mp3", 2, status)
x = playsong("c:\1.mp3", Val(status) - 5000)
x = statussong("c:\1.mp3", 1, status)
Text1.Text = status
End Sub

这样就可以了，如果大家有兴趣，可以亲自试一下！