底层音频服务的原理和delphi实现(200分)

请为我讲解一下底层音频服务的原理和API的使用及DELPHI实现的例子

是指MCI吗？ 嘻嘻，前段时间刚看了一阵，做了一个小控件（在高手指点下）。

见问题http://www.gislab.ecnu.edu.cn/delphibbs/DispQ.asp?LID=193079
感兴趣给我Mail cheka@yeah.net

不是MCI，是MMSYSTEMP单元中定义的个函数，我想了解声音编辑的细节

是指 waveInxxxx ?

這問題很複雜哦

#include
#include
#include "resource.h"

#define SAMPLE_RATE 11025
#define FREQ_MIN 20
#define FREQ_MAX 5000
#define FREQ_INIT 440
#define OUT_BUFFER_SIZE 4096
#define PI 3.14159

BOOL CALLBACK DlgProc (HWND, UINT, WPARAM, LPARAM)

TCHAR szAppName [] = TEXT ("SineWave")

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
PSTR szCmdLine, int iCmdShow)
{
if (-1 == DialogBox (hInstance, szAppName, NULL, DlgProc))
{
MessageBox (NULL, TEXT ("This program requires Windows NT!"),
szAppName, MB_ICONERROR)
}
return 0
}

VOID FillBuffer (PBYTE pBuffer, int iFreq)
{
staticdo
uble fAngle
int i

for (i = 0
i < OUT_BUFFER_SIZE
i++)
{
pBuffer = (BYTE) (127 + 127 * sin (fAngle))

fAngle += 2 * PI * iFreq / SAMPLE_RATE

if (fAngle > 2 * PI)
fAngle -= 2 * PI
}
}

BOOL CALLBACK DlgProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
static BOOL bShutOff, bClosing
static HWAVEOUT hWaveOut
static HWND hwndScroll
static int iFreq = FREQ_INIT
static PBYTE pBuffer1, pBuffer2
static PWAVEHDR pWaveHdr1, pWaveHdr2
static WAVEFORMATEX waveformat
int iDummy

switch (message)
{
case WM_INITDIALOG:
hwndScroll = GetDlgItem (hwnd, IDC_SCROLL)
SetScrollRange (hwndScroll, SB_CTL, FREQ_MIN, FREQ_MAX, FALSE)
SetScrollPos (hwndScroll, SB_CTL, FREQ_INIT, TRUE)
SetDlgItemInt (hwnd, IDC_TEXT, FREQ_INIT, FALSE)

return TRUE

case WM_HSCROLL:
switch (LOWORD (wParam))
{
case SB_LINELEFT: iFreq -= 1
break
case SB_LINERIGHT: iFreq += 1
break
case SB_PAGELEFT: iFreq /= 2
break
case SB_PAGERIGHT: iFreq *= 2
break

case SB_THUMBTRACK:
iFreq = HIWORD (wParam)
break

case SB_TOP:
GetScrollRange (hwndScroll, SB_CTL, &amp;
ifreq, &amp;iDummy)
break

case SB_BOTTOM:
GetScrollRange (hwndScroll, SB_CTL, &amp;iDummy, &amp;
ifreq)
break
}

iFreq = max (FREQ_MIN, min (FREQ_MAX, iFreq))

SetScrollPos (hwndScroll, SB_CTL, iFreq, TRUE)
SetDlgItemInt (hwnd, IDC_TEXT, iFreq, FALSE)
return TRUE

case WM_COMMAND:
switch (LOWORD (wParam))
{
case IDC_ONOFF:
// If turning on waveform, hWaveOut is NULL

if (hWaveOut == NULL)
{
// Allocate memory for 2 headers and 2 buffers

pWaveHdr1 = malloc (sizeof (WAVEHDR))
pWaveHdr2 = malloc (sizeof (WAVEHDR))
pBuffer1 = malloc (OUT_BUFFER_SIZE)
pBuffer2 = malloc (OUT_BUFFER_SIZE)

if (!pWaveHdr1 || !pWaveHdr2 || !pBuffer1 || !pBuffer2)
{
if (!pWaveHdr1) free (pWaveHdr1)
if (!pWaveHdr2) free (pWaveHdr2)
if (!pBuffer1) free (pBuffer1)
if (!pBuffer2) free (pBuffer2)

MessageBeep (MB_ICONEXCLAMATION)
MessageBox (hwnd, TEXT ("Error allocating memory!"),
szAppName, MB_ICONEXCLAMATION | MB_OK)
return TRUE
}

// Variable to indicate Off button pressed

bShutOff = FALSE

// Open waveform audio for output

waveformat.wFormatTag = WAVE_FORMAT_PCM
waveformat.nChannels = 1
waveformat.nSamplesPerSec = SAMPLE_RATE
waveformat.nAvgBytesPerSec = SAMPLE_RATE
waveformat.nBlockAlign = 1
waveformat.wBitsPerSample = 8
waveformat.cbSize = 0

if (waveOutOpen (&amp;hWaveOut, WAVE_MAPPER, &amp;waveformat,
(DWORD) hwnd, 0, CALLBACK_WINDOW)
!= MMSYSERR_NOERROR)
{
free (pWaveHdr1)
free (pWaveHdr2)
free (pBuffer1)
free (pBuffer2)

hWaveOut = NULL
MessageBeep (MB_ICONEXCLAMATION)
MessageBox (hwnd,
TEXT ("Error opening waveform audio device!"),
szAppName, MB_ICONEXCLAMATION | MB_OK)
return TRUE
}

// Set up headers and prepare them

pWaveHdr1->lpData = pBuffer1
pWaveHdr1->dwBufferLength = OUT_BUFFER_SIZE
pWaveHdr1->dwBytesRecorded = 0
pWaveHdr1->dwUser = 0
pWaveHdr1->dwFlags = 0
pWaveHdr1->dwLoops = 1
pWaveHdr1->lpNext = NULL
pWaveHdr1->reserved = 0

waveOutPrepareHeader (hWaveOut, pWaveHdr1,
sizeof (WAVEHDR))

pWaveHdr2->lpData = pBuffer2
pWaveHdr2->dwBufferLength = OUT_BUFFER_SIZE
pWaveHdr2->dwBytesRecorded = 0
pWaveHdr2->dwUser = 0
pWaveHdr2->dwFlags = 0
pWaveHdr2->dwLoops = 1
pWaveHdr2->lpNext = NULL
pWaveHdr2->reserved = 0

waveOutPrepareHeader (hWaveOut, pWaveHdr2,
sizeof (WAVEHDR))
}
// If turning off waveform, reset waveform audio
else

{
bShutOff = TRUE
waveOutReset (hWaveOut)
}
return TRUE
}
break

// Message generated from waveOutOpen call

case MM_WOM_OPEN:
SetDlgItemText (hwnd, IDC_ONOFF, TEXT ("Turn Off"))

// Send two buffers to waveform output device

FillBuffer (pBuffer1, iFreq)
waveOutWrite (hWaveOut, pWaveHdr1, sizeof (WAVEHDR))

FillBuffer (pBuffer2, iFreq)
waveOutWrite (hWaveOut, pWaveHdr2, sizeof (WAVEHDR))
return TRUE

// Message generated when a buffer is finished

case MM_WOM_DONE:
if (bShutOff)
{
waveOutClose (hWaveOut)
return TRUE
}

// Fill and send out a new buffer

FillBuffer (((PWAVEHDR) lParam)->lpData, iFreq)
waveOutWrite (hWaveOut, (PWAVEHDR) lParam, sizeof (WAVEHDR))
return TRUE

case MM_WOM_CLOSE:
waveOutUnprepareHeader (hWaveOut, pWaveHdr1, sizeof (WAVEHDR))
waveOutUnprepareHeader (hWaveOut, pWaveHdr2, sizeof (WAVEHDR))

free (pWaveHdr1)
free (pWaveHdr2)
free (pBuffer1)
free (pBuffer2)

hWaveOut = NULL
SetDlgItemText (hwnd, IDC_ONOFF, TEXT ("Turn On"))

if (bClosing)
EndDialog (hwnd, 0)

return TRUE

case WM_SYSCOMMAND:
switch (wParam)
{
case SC_CLOSE:
if (hWaveOut != NULL)
{
bShutOff = TRUE
bClosing = TRUE

waveOutReset (hWaveOut)
}
else

EndDialog (hwnd, 0)

return TRUE
}
break
}
return FALSE
}

多人接受答案了。