Trying to write functions that record and play sound through WinAPI

Question

I'm trying to create 2 functions in C :

• One that record the microphone for X seconds
• One that gets a recording, and play it to the user

This is what I wrote :

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

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

WAVEHDR StartRecord(int seconds)
{
const int NUMPTS = 44100 * seconds;
int sampleRate = 44100;
short int *waveIn = new short int[NUMPTS];

HWAVEIN hWaveIn;
WAVEHDR WaveInHdr;
MMRESULT result;

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);
}

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);
}

result = waveInStart(hWaveIn);
if(result)
{
    MessageBoxA(NULL, "Failed to start recording", NULL, MB_OK | MB_ICONEXCLAMATION);
}

cout << "Recording..." << endl;
Sleep(seconds * 1000); //Sleep while recording

return WaveInHdr;

}

void PlayRecord(WAVEHDR WaveInHdr, int seconds)
{
WAVEFORMATEX pFormat;
pFormat.wFormatTag = WAVE_FORMAT_PCM;
pFormat.nChannels = 1;
pFormat.nSamplesPerSec = 44100;
pFormat.nAvgBytesPerSec = 2 * 44100;
pFormat.nBlockAlign = 2;
pFormat.wBitsPerSample = 16;
pFormat.cbSize = 0;

HWAVEOUT hWaveOut;

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)); // Playing the data
Sleep(seconds * 1000); //Sleep for as long as there was recorded
 }

int main()
{
PlayRecord(StartRecord(3), 3);
return 0;
}

Whats wrong with the code? Why doesnt it work ? I cant seem to hear anything...

Also, is there an option to record the microphone, instead of X seconds, to record it for example untill there is no input from the microphone (for example - start recording it, I'm saying a word into the microphone, and when theres a silence for a second or two it stops recording or something?)

Thanks!

Answer 1

Re: recording until there is no input from the microphone. Yes, prepare several buffers and call waveInAddBuffer with each of them before you WaveInStart. WaveIn will continuously and sequentially fill the buffers and return them to you as they are filled. You will need to use one of the notifications provided by WaveIn to know when a buffer has been filled. Examine the buffer data to decide when to stop. If you want to keep going then give each filled buffer back to WaveIn and it will keep filling them as long as you want.