I want to know obs's virtual camera technology.

[Teruya-Inoue]

I'd like to use obs's virtual camera technology.
I found out that shared memory is used.
Use the following program as a reference

• plugins/win-dshow/virtualcam.c
• plugins/win-dshow/shared-memory-queue.c

I tried to write to the shared memory to see if the image would be displayed, but it did not work.
Please let me know if there is a better way.

The following is the source code.
`#include <opencv2/opencv.hpp>
#include
#include <windows.h>

using namespace std;
#define VIDEO_NAME L"OBSVirtualCamVideo"
#define ALIGN_SIZE(size, align) size = (((size) + (align - 1)) & (~(align - 1)))
#define FRAME_HEADER_SIZE 32

struct queue_header {
volatile uint32_t write_idx;
volatile uint32_t read_idx;
volatile uint32_t state;

uint32_t offsets[3];

uint32_t type;

uint32_t cx;
uint32_t cy;
uint64_t interval;

uint32_t reserved[8];

};

struct video_queue {
HANDLE handle;
bool ready_to_read;
struct queue_header* header;
uint64_t* ts[3];
uint8_t* frame[3];
long last_inc;
int dup_counter;
bool is_writer;
};

int main(void)
{
cv::Mat img = cv::imread("1.jpg");
int cx = img.rows;
int cy = img.cols;
cv::cvtColor(img, img, cv::COLOR_BGR2YUV);

struct video_queue vq = { 0 };
struct video_queue* pvq;
DWORD frame_size = cx * cy * 3 / 2;
uint32_t offset_frame[3];
DWORD size;

size = sizeof(struct queue_header);

ALIGN_SIZE(size, 32);

offset_frame[0] = size;
size += frame_size + FRAME_HEADER_SIZE;
ALIGN_SIZE(size, 32);

offset_frame[1] = size;
size += frame_size + FRAME_HEADER_SIZE;
ALIGN_SIZE(size, 32);

offset_frame[2] = size;
size += frame_size + FRAME_HEADER_SIZE;
ALIGN_SIZE(size, 32);

struct queue_header header = { 0 };

vq.handle = CreateFileMappingW(INVALID_HANDLE_VALUE, NULL,
	PAGE_READWRITE, 0, size, VIDEO_NAME);
if (!vq.handle) {
	return NULL;
}

vq.header = (struct queue_header*)MapViewOfFile(
	vq.handle, FILE_MAP_ALL_ACCESS, 0, 0, 0);
if (!vq.header) {
	CloseHandle(vq.handle);
	return NULL;
}

while (1) {
	memcpy(vq.frame,img.data, sizeof(img.data));
}

return 0;

}`