Sensoray 811 Windows SDK - Manual (Page 16)

Returns
0 on success, negative value if error (see mid811types.h for error codes list).
MID811_API int S811_SetMute(
BOOL bMute,
int devid
);
Mutes audio on the host computer. Audio will still be recorded.
Parameters
bMute
TRUE to mute the audio.
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_GetMute(
BOOL *bMute,
int devid
);
Retrieves current audio playback setting.
Parameters
bMute
pointer to retrieved setting.
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).
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