Sensoray 811 Windows SDK - Manual (Page 23)

Same as S811_SnapshotToFile, but uses Unicode filenames
MID811_API int S811_GetVideoSize(
RECT *prect,
int devid,
);
Retrieves the current video rectangle size.
Parameters
prect
Retrieved pointer to rectangle.
devid
current device id.
Returns
0 on success, negative value if error (see mid811types.h for error codes list).
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