PlaySound too slow on slower PCs? - c

Question

I made a program that outputs a click-sound whenever a key on the keyboard has been pressed.
When I tried the program on my pc (with Ryzen 3900x) and on one of my laptops (with i7 8850h) it outputted the sound flawlessly without any delay, even when typing fast.
But on a slower laptop I use for school, it is not outputting the sound right, especially when typing fast. (The sound is either delayed or it only plays a little part before stopping)
I cant really find an issue other than that PlaySound might be too slow or something. It hasn't anything to do with loading the sound-file, because I am playing the sound from memory. It is also not the recognition of a key-press, because the console output (which key gets pressed) is almost instantly.
Here is my code:
#ifndef UNICODE
#define UNICODE
#endif // UNICODE
#include <stdio.h>
#include <stdlib.h>
#include <w32api.h>
#define WINVER WindowsXP
#include <windows.h>
#include <winuser.h>
BYTE* byteAudio = NULL;
LRESULT CALLBACK WinProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
if(uMsg == WM_INPUT)
{
HRAWINPUT hRawInput = (HRAWINPUT)lParam;
RAWINPUT input = { 0 };
UINT size = sizeof(input);
GetRawInputData(hRawInput, RID_INPUT,&input,&size,sizeof(RAWINPUTHEADER));
if(input.data.keyboard.Flags == 0)
{
//PlaySoundW(TEXT("res/click.wav"), NULL, SND_ASYNC | SND_FILENAME);
PlaySound(byteAudio, SND_MEMORY, SND_ASYNC | SND_MEMORY);
printf("vkey: %x, flag: %d\n",input.data.keyboard.VKey, input.data.keyboard.Flags);
}
}
return DefWindowProc(hwnd, uMsg, wParam, lParam);
}
int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpComLine, int iShowCmd)
{
const char* CLASS_NAME = "RawInputClass";
FILE* fPtr;
long lFileSize;
//Gets file size
fPtr = fopen("res/click.wav", "rb");
if(!fPtr)
{
printf("Error while opening file!");
return -1;
}
fseek(fPtr, 0, SEEK_END);
lFileSize = ftell(fPtr);
rewind(fPtr);
//Reads file into byte-Array
byteAudio = (BYTE*)malloc(lFileSize * sizeof(BYTE));
if(!byteAudio)
{
printf("byteAudio; OUT_OF_MEMORY"); //If that happens, it is probably time for an upgrade
return -1;
}
fread(byteAudio, lFileSize, 1, fPtr);
fclose(fPtr);
//Create Message-Only window
WNDCLASS wnd = { 0 };
wnd.hInstance = GetModuleHandle(NULL);
wnd.lpfnWndProc = WinProc;
wnd.lpszClassName = CLASS_NAME;
RegisterClass(&wnd);
HWND hWnd = CreateWindowExW(0, CLASS_NAME, TEXT("THE WINDOW IS INVISIBLE SO WHO CARES!"),
0, 0, 0, 0, 0, HWND_MESSAGE, NULL, GetModuleHandle(NULL), NULL);
RAWINPUTDEVICE rid = { 0 };
rid.usUsagePage = 0x01;
rid.usUsage = 0x06; //keyboard
rid.dwFlags = RIDEV_INPUTSINK | RIDEV_NOLEGACY;
rid.hwndTarget = hWnd;
RegisterRawInputDevices(&rid, 1, sizeof(RAWINPUTDEVICE));
MSG msg;
while(GetMessage(&msg, NULL, 0, 0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
}

Answer 1

You are using a polling method, which is slow.
while(GetMessage(&msg, NULL, 0, 0))
{
/* stuff */
}
Read about what interrupts are and for what those interrupts are used. These will solve your problem.