hello, I have wirte a demo to test the interval of two frame:

```
int main(){
// Create a ZED camera object
Camera zed;
InitParameters init_parameters;
init_parameters.camera_fps = 30;
init_parameters.camera_resolution = RESOLUTION::HD1080;
// Open the camera
ERROR_CODE returned_state = zed.open(init_parameters);
if (returned_state != ERROR_CODE::SUCCESS) {
std::cout << "Error " << returned_state << ", exit program.\n";
zed.close();
return EXIT_FAILURE;
}
Mat image_zed;
int i = 0;
unsigned long previous = 0;
while (true){
if (zed.grab() == ERROR_CODE::SUCCESS){
zed.retrieveImage(image_zed, VIEW::LEFT);
auto zed_ts = image_zed.timestamp.getMilliseconds();
if (i != 0){
if ((zed_ts - previous) > 20) {
std::cout << "previous is " << previous << " current is " << zed_ts << " gap " << zed_ts - previous << std::endl;
}
}
previous = zed_ts;
if (i == 100)
break;
i++;
}
}
// Close the camera
zed.close();
return EXIT_SUCCESS;
}
```

And i got the result as below:

```
previous is 1649384857768 current is 1649384857835 gap 67
previous is 1649384857835 current is 1649384857868 gap 33
previous is 1649384857868 current is 1649384857902 gap 34
previous is 1649384857902 current is 1649384857935 gap 33
previous is 1649384857935 current is 1649384857968 gap 33
previous is 1649384857968 current is 1649384858035 gap 67
previous is 1649384858035 current is 1649384858102 gap 67
previous is 1649384858102 current is 1649384858136 gap 34
previous is 1649384858136 current is 1649384858169 gap 33
previous is 1649384858169 current is 1649384858236 gap 67
previous is 1649384858236 current is 1649384858336 gap 100
previous is 1649384858336 current is 1649384858369 gap 33
previous is 1649384858369 current is 1649384858436 gap 67
previous is 1649384858436 current is 1649384858503 gap 67
previous is 1649384858503 current is 1649384858537 gap 34
previous is 1649384858537 current is 1649384858570 gap 33
previous is 1649384858570 current is 1649384858603 gap 33
previous is 1649384858603 current is 1649384858670 gap 67
previous is 1649384858670 current is 1649384858704 gap 34
previous is 1649384858704 current is 1649384858737 gap 33
previous is 1649384858737 current is 1649384858770 gap 33
previous is 1649384858770 current is 1649384858837 gap 67
previous is 1649384858837 current is 1649384858871 gap 34
previous is 1649384858871 current is 1649384858904 gap 33
previous is 1649384858904 current is 1649384858937 gap 33
previous is 1649384858937 current is 1649384858971 gap 34
previous is 1649384858971 current is 1649384859004 gap 33
previous is 1649384859004 current is 1649384859038 gap 34
previous is 1649384859038 current is 1649384859071 gap 33
previous is 1649384859071 current is 1649384859138 gap 67
previous is 1649384859138 current is 1649384859172 gap 34
```

Itâ€™ indicate that the interval of adjacent frame is not exactly be 33 or 34 when i set camera fps to 30, so is it means that the camera has droped frame ?