Windows API Function AVIFileOpenW takes PAVISTREAM as input but AVIStreamSetFormat takes PAVIFILE

Question

I am making a clipping software which clips the last 30 seconds of your screen. I am trying to write the results to an AVI file, but I am running into issues. Here is my code:

#include <Windows.h>
#include <Vfw.h>
#include <iostream>
#include <vector>

const int BUFFER_SIZE = 30 * 60; // 30 seconds at 60 fps

int main() {
    HMONITOR hMonitor = MonitorFromWindow(NULL, MONITOR_DEFAULTTOPRIMARY);
    MONITORINFO info;
    info.cbSize = sizeof(MONITORINFO);
    GetMonitorInfo(hMonitor, &info);
    int width = info.rcMonitor.right - info.rcMonitor.left;
    int height = info.rcMonitor.bottom - info.rcMonitor.top;

    HDC hDC = GetDC(NULL);

    HBITMAP hBitmap = CreateCompatibleBitmap(hDC, width, height);

    // Create a device context for the bitmap
    HDC hMemDC = CreateCompatibleDC(hDC);
    SelectObject(hMemDC, hBitmap);

    std::vector<HBITMAP> buffer(BUFFER_SIZE);
    int index = 0;

    while (true) {
        BitBlt(hMemDC, 0, 0, width, height, hDC, 0, 0, SRCCOPY);

        buffer[index] = hBitmap;
        index = (index + 1) % BUFFER_SIZE;

        if (GetAsyncKeyState(VK_ESCAPE) & 0x8000) {
            break;
        }
    }

    // PROBLEM HERE:

    PAVISTREAM pStream;
    AVIFileInit();
    AVIFileOpenW(&pStream, L"screen_recording.avi", OF_WRITE | OF_CREATE, NULL); // takes PAVIFILE as first parameter 
    AVIStreamSetFormat(pStream, 0, &hBitmap, sizeof(BITMAPINFOHEADER)); // takes PAVISTREAM as first parameter

    // Write the stored frames to the AVISTREAM object
    for (int i = 0; i < BUFFER_SIZE; i++) {
        AVIStreamWrite(pStream, i, 1, &buffer[i], sizeof(BITMAPINFOHEADER), AVIIF_KEYFRAME, NULL, NULL);
    }

    AVIStreamClose(pStream);
    AVIFileExit();

    ReleaseDC(NULL, hDC);
    DeleteDC(hMemDC);
    DeleteObject(hBitmap);

    return 0;
}

Am I doing this right? I am new to C++, so I am not sure if this is what I should be doing.

Answer 1

You can use the function AVIStreamOpenFromFile to open the avi file as stream, that will give the pointer to PAVISTREAM. So, not necessary to call the AVIFileOpen function.