Sensoray 811 Windows SDK - Manual (Page 9)

int *pNumDevices
);
Retrieve the number of devices in the system. 4 devices per board.
Parameters
pNumDevices
Returns the number of devices(Note: 4 channels/devices per 811 board).
Returns
0 if success, negative if error.
MID811_API int S811_SetSource(
MID811_SOURCE input,
int devid
);
Selects between composite and S-video inputs.
Parameters
input
enumerated input MID811_SOURCE (see mid811types.h). For model 314 the allowed values
are MID811_SOURCE_COMPOSITE_0, MID811_SOURCE_COMPOSITE_1,
MID811_SOURCE_COMPOSITE_2, MID811_SOURCE_COMPOSITE_3,
MID811_SOURCE_SVIDEO_0 and MID811_SOURCE_SVIDEO_1.
devid
device id in the system (use 0 for first channel with a single board installed).
Returns
0 on success, negative value if error (see mid811types.h for error codes list).
MID811_API int S811_GetSource(
MID811_SOURCE *pSource,
int devid
);
Retrieves current input settings.
Parameters
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