Created
August 23, 2013 09:27
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Sample code for the waveOutWrite function.
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#include <windows.h> | |
#include <mmsystem.h> | |
#pragma comment(lib, "winmm.lib") | |
int main() | |
{ | |
HWAVEOUT hWaveOut = 0; | |
WAVEFORMATEX wfx = { WAVE_FORMAT_PCM, 1, 8000, 8000, 1, 8, 0 }; | |
waveOutOpen(&hWaveOut, WAVE_MAPPER, &wfx, 0, 0, CALLBACK_NULL); | |
char buffer[8000 * 60] = {}; | |
// See http://goo.gl/hQdTi | |
for (DWORD t = 0; t < sizeof(buffer); ++t) | |
buffer[t] = static_cast<char>((((t * (t >> 8 | t >> 9) & 46 & t >> 8)) ^ (t & t >> 13 | t >> 6)) & 0xFF); | |
WAVEHDR header = { buffer, sizeof(buffer), 0, 0, 0, 0, 0, 0 }; | |
waveOutPrepareHeader(hWaveOut, &header, sizeof(WAVEHDR)); | |
waveOutWrite(hWaveOut, &header, sizeof(WAVEHDR)); | |
waveOutUnprepareHeader(hWaveOut, &header, sizeof(WAVEHDR)); | |
waveOutClose(hWaveOut); | |
Sleep(60 * 1000); | |
} |
It works perfectly as is. Just tried it in an empty console application. No callback is needed.
Note the Windows docs also say the callback mechanism can be NULL.
https://learn.microsoft.com/en-us/windows/win32/api/mmeapi/nf-mmeapi-waveoutopen?redirectedfrom=MSDN
This is an example that uses several buffers, without needing a huge buffer, and loops around them whilst dynamically calculating the samples:
#include <stdio.h>
#include <windows.h>
#include <mmsystem.h>
#pragma comment(lib, "winmm.lib")
int main()
{
HWAVEOUT hWaveOut = 0;
WAVEFORMATEX wfx = { WAVE_FORMAT_PCM, 1, 8000, 8000, 1, 8, 0 };
waveOutOpen(&hWaveOut, WAVE_MAPPER, &wfx, 0, 0, CALLBACK_NULL);
// Make this size at least a good fraction of the sample rate.
const DWORD chunkSize = 500;
// It is good to have at least two buffers. One buffer causes crackles in the sound output.
const DWORD numHeaders = 2;
WAVEHDR headers[numHeaders];
char bufferData[numHeaders][chunkSize];
// Setup all buffers to be "done" so they are filled the first time around
for (int i = 0 ; i < numHeaders ; i++)
{
headers[i].dwFlags = WHDR_DONE;
}
DWORD blockIndex = 0;
// This demonstrates sending data as chunks into the output headers
// Note no callback is needed because we test the dwFlags for WHDR_DONE
DWORD t = 0;
while (true)
{
WAVEHDR *header = headers+blockIndex;
// Fill any buffers that are "done"
if (header->dwFlags & WHDR_DONE)
{
printf("Setup for position = %d\n" , t);
header->dwFlags = 0;
header->lpData = bufferData[blockIndex];
// Calculate a new chunk of data
for (int i = 0 ; i < chunkSize ; i++)
{
// See http://goo.gl/hQdTi
bufferData[blockIndex][i] = static_cast<char>((((t * (t >> 8 | t >> 9) & 46 & t >> 8)) ^ (t & t >> 13 | t >> 6)) & 0xFF);
t++;
}
header->dwBufferLength = chunkSize;
waveOutPrepareHeader(hWaveOut, header, sizeof(WAVEHDR));
waveOutWrite(hWaveOut, header, sizeof(WAVEHDR));
waveOutUnprepareHeader(hWaveOut, header, sizeof(WAVEHDR));
}
// Test the next buffer
blockIndex++;
if (blockIndex == numHeaders)
{
// If we have tested all buffers, then sleep for a very short while to avoid blocking the whole thread
blockIndex = 0;
Sleep(10);
}
}
waveOutClose(hWaveOut);
}
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This doesn't work, because the UnprepareHeader and Close functions need to be called only after the buffer is written. A callback function in the waveoutopen function would be needed.