Audio live streaming

[MAS1496]

I am recording my voice using mic. I have used waveIn() and waveOut() function for this purpose. When I start recording using waveInStart() function, it first completely record my voice for specified time and store it in a ()buffer and later play back my voice from that buffer. During recording and during playing , it does nothing. I want to record and play at the same time .
for that purpose I want to access the buffer during recording . How is this possible ? Or any other suggestion will be helpful.

Here is the code :


#include <iostream>
#include <Windows.h>
using namespace std;

#pragma comment(lib, "winmm.lib")

short int waveIn[8000 * 3];

void PlayRecord();
void writedataTofile(LPSTR lpData,DWORD dwBufferLength);

void StartRecord()
{
const int NUMPTS = 8000 * 3; // 3 seconds
int sampleRate = 8000;
// 'short int' is a 16-bit type; I request 16-bit samples below
// for 8-bit capture, you'd use 'unsigned char' or 'BYTE' 8-bit types

HWAVEIN hWaveIn;
MMRESULT result;

WAVEFORMATEX pFormat;
pFormat.wFormatTag=WAVE_FORMAT_PCM; // simple, uncompressed format
pFormat.nChannels=1; // 1=mono, 2=stereo
pFormat.nSamplesPerSec=sampleRate; // 8.0 kHz, 11.025 kHz, 22.05 kHz, and 44.1 kHz
pFormat.nAvgBytesPerSec=sampleRate*2; // = nSamplesPerSec × nBlockAlign
pFormat.nBlockAlign=2; // = (nChannels × wBitsPerSample) / 8
pFormat.wBitsPerSample=16; // 16 for high quality, 8 for telephone-grade
pFormat.cbSize=0;

// Specify recording parameters

result = waveInOpen(&hWaveIn, WAVE_MAPPER,&pFormat,
0L, 0L, WAVE_FORMAT_DIRECT);

WAVEHDR WaveInHdr;
// Set up and prepare header for input
WaveInHdr.lpData = (LPSTR)waveIn;
WaveInHdr.dwBufferLength = NUMPTS*2;
WaveInHdr.dwBytesRecorded=0;
WaveInHdr.dwUser = 0L;
WaveInHdr.dwFlags = 0L;
WaveInHdr.dwLoops = 0L;
waveInPrepareHeader(hWaveIn, &WaveInHdr, sizeof(WAVEHDR));

// Insert a wave input buffer
result = waveInAddBuffer(hWaveIn, &WaveInHdr, sizeof(WAVEHDR));


// Commence sampling input
result = waveInStart(hWaveIn);


cout << "recording..." << endl;

Sleep(3 * 1000);
// Wait until finished recording

waveInClose(hWaveIn);
PlayRecord();
}

void PlayRecord()
{
const int NUMPTS = 8000 * 3; // 3 seconds
int sampleRate = 8000;
// 'short int' is a 16-bit type; I request 16-bit samples below
// for 8-bit capture, you'd use 'unsigned char' or 'BYTE' 8-bit types

HWAVEIN hWaveIn;

WAVEFORMATEX pFormat;
pFormat.wFormatTag=WAVE_FORMAT_PCM; // simple, uncompressed format
pFormat.nChannels=1; // 1=mono, 2=stereo
pFormat.nSamplesPerSec=sampleRate; // 44100
pFormat.nAvgBytesPerSec=sampleRate*2; // = nSamplesPerSec * n.Channels * wBitsPerSample/8
pFormat.nBlockAlign=2; // = n.Channels * wBitsPerSample/8
pFormat.wBitsPerSample=16; // 16 for high quality, 8 for telephone-grade
pFormat.cbSize=0;

// Specify recording parameters

waveInOpen(&hWaveIn, WAVE_MAPPER,&pFormat, 0L, 0L, WAVE_FORMAT_DIRECT);

WAVEHDR WaveInHdr;
// Set up and prepare header for input
WaveInHdr.lpData = (LPSTR)waveIn;
WaveInHdr.dwBufferLength = NUMPTS*2;
WaveInHdr.dwBytesRecorded=0;
WaveInHdr.dwUser = 0L;
WaveInHdr.dwFlags = 0L;
WaveInHdr.dwLoops = 0L;
waveInPrepareHeader(hWaveIn, &WaveInHdr, sizeof(WAVEHDR));

HWAVEOUT hWaveOut;
cout << "playing..." << endl;
waveOutOpen(&hWaveOut, WAVE_MAPPER, &pFormat, 0, 0, WAVE_FORMAT_DIRECT);
waveOutWrite(hWaveOut, &WaveInHdr, sizeof(WaveInHdr)); // Playing the data
Sleep(3 * 1000); //Sleep for as long as there was recorded


waveInClose(hWaveIn);
waveOutClose(hWaveOut);
}
int main()
{
StartRecord();
return 0;
}

[plexus]

You have to use multiple threads for capturing and playback at the same time.
For that you should use smaller buffers because you can't write to and read from the same buffer at once. While the capture driver fills one buffer you play back from another.

To syncronize the threads and coordinate the use of the buffers you should use events or mutexes.
Have a look here: https://msdn.microsoft.com/en-us/library/windows/desktop/ms681924%28v=vs.85%29.aspx

Maybe callback functions work too, but I'm not sure about that. I used them only for either wave in or wave out, but not for both simultaneously. I think threads are better for that.