我想播放从 IP 摄像机接收到的音频。压缩音频数据的格式为 G726 ADPCM。
我在互联网上搜索了几天,但我还没有这样做。
我尝试了很多很多方法来播放它。尝试解码为 PCM 并构建头文件以创建 Wave 文件,但一切都失败了(也许我在做的时候有一些错误)。
但是今天,我找到了用于从 PC 录制和播放波形音频的代码。
这是代码:
// ADPCM.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include <iostream>
#include <Windows.h>
#include <MMSystem.h>
using namespace std;
int _tmain(int argc, _TCHAR* argv[])
{
const int NUMPTS = 8000*10;//44100 * 10;
int sampleRate = 8000;//44100;
short int waveIn[NUMPTS];
HWAVEIN hWaveIn;
WAVEHDR WaveInHdr;
MMRESULT result;
HWAVEOUT hWaveOut;
WAVEFORMATEX pFormat;
pFormat.wFormatTag = WAVE_FORMAT_PCM;
pFormat.nChannels = 1;
pFormat.nSamplesPerSec = sampleRate;
pFormat.nAvgBytesPerSec = 2 * sampleRate;
pFormat.nBlockAlign = 2;
pFormat.wBitsPerSample = 16;
pFormat.cbSize = 0;
result = waveInOpen(&hWaveIn, WAVE_MAPPER, &pFormat, 0, 0, WAVE_FORMAT_DIRECT);
if(result)
{
char fault[256];
waveInGetErrorTextA(result, fault, 256);
MessageBoxA(NULL, fault, "Failed to open waveform input device.", MB_OK | MB_ICONEXCLAMATION);
return 1;
}
WaveInHdr.lpData = (LPSTR)waveIn;
WaveInHdr.dwBufferLength = 2 * NUMPTS;
WaveInHdr.dwBytesRecorded = 0;
WaveInHdr.dwUser = 0;
WaveInHdr.dwFlags = 0;
WaveInHdr.dwLoops = 0;
waveInPrepareHeader(hWaveIn, &WaveInHdr, sizeof(WAVEHDR));
result = waveInAddBuffer(hWaveIn, &WaveInHdr, sizeof(WAVEHDR));
if(result)
{
MessageBoxA(NULL, "Failed to read block from device", NULL, MB_OK | MB_ICONEXCLAMATION);
return 1;
}
result = waveInStart(hWaveIn);
if(result)
{
MessageBoxA(NULL, "Failed to start recording", NULL, MB_OK | MB_ICONEXCLAMATION);
return 1;
}
cout << "Recording..." << endl;
Sleep((NUMPTS/sampleRate) * 1000); //Sleep while recording
cout << "Playing..." << endl;
if(waveOutOpen(&hWaveOut, WAVE_MAPPER, &pFormat, 0, 0, WAVE_FORMAT_DIRECT))
{
MessageBoxA(NULL, "Failed to replay", NULL, MB_OK | MB_ICONEXCLAMATION );
}
waveOutWrite(hWaveOut, &WaveInHdr, sizeof(WaveInHdr));
Sleep((NUMPTS/sampleRate) * 1000); //Sleep for as long as there was recorded
waveOutUnprepareHeader(hWaveOut, &WaveInHdr, sizeof(WAVEHDR));
waveInUnprepareHeader(hWaveIn, &WaveInHdr, sizeof(WAVEHDR));
waveInClose(hWaveIn);
waveOutClose(hWaveOut);
return 0;
}
我将 PCM 数据存储在我的缓冲区中,我想修改上面的代码来播放它,所以我将它编辑为以下代码:
const int NUMPTS = 4000;//44100 * 10;
int sampleRate = 8000;//44100;
CHAR waveIn[NUMPTS];
HWAVEIN hWaveIn;
WAVEHDR WaveInHdr;
MMRESULT result;
HWAVEOUT hWaveOut;
WAVEFORMATEX pFormat;
pFormat.wFormatTag = WAVE_FORMAT_PCM;
pFormat.nChannels = 1;
pFormat.nSamplesPerSec = sampleRate;
pFormat.nAvgBytesPerSec = sampleRate/2;//2 * sampleRate;
pFormat.nBlockAlign = 1;//2;
pFormat.wBitsPerSample = 4;//16;
pFormat.cbSize = 0;
WaveInHdr.lpData = (LPSTR)waveIn;
WaveInHdr.dwBufferLength = 2 * NUMPTS;
WaveInHdr.dwBytesRecorded = 0;
WaveInHdr.dwUser = 0;
WaveInHdr.dwFlags = 0;
WaveInHdr.dwLoops = 0;
waveInPrepareHeader(hWaveIn, &WaveInHdr, sizeof(WAVEHDR));
memcpy(WaveInHdr.lpData, myPCMBuffer, NUMPTS);
waveOutWrite(hWaveOut, &WaveInHdr, sizeof(WaveInHdr));
waveOutUnprepareHeader(hWaveOut, &WaveInHdr, sizeof(WAVEHDR));
waveInUnprepareHeader(hWaveIn, &WaveInHdr, sizeof(WAVEHDR));
waveInClose(hWaveIn);
waveOutClose(hWaveOut);
但是当调用 waveOutUnprepareHeader() 时,它会抛出消息“运行时检查失败 #3 - 正在使用变量 'hWaveIn' 而未初始化”。
如何初始化 hWaveIn?
这是我第一次使用波形音频,所以我很愚蠢^^。
你能告诉我正确的方法吗?