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[The feature associated with this page, DirectShow, is a legacy feature. It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation. Those features have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use MediaPlayer, IMFMediaEngine and Audio/Video Capture in Media Foundation instead of DirectShow, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]
The SignalPresent method retrieves the strength of the signal on a given channel.
Syntax
HRESULT SignalPresent(
[out] long *plSignalStrength
);
Parameters
[out] plSignalStrength
Pointer to a variable that receives a value indicating whether a signal is present on the current channel. Can be one of the following values.
| Value | Description |
|---|---|
| AMTUNER_HASNOSIGNALSTRENGTH | -1 |
| AMTUNER_NOSIGNAL | 0 |
| AMTUNER_SIGNALPRESENT | 1 |
A value of AMTUNER_HASNOSIGNALSTRENGTH means the signal strength cannot be determined at this time.
Return value
Returns an HRESULT value.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows 2000 Professional [desktop apps only] |
| Minimum supported server | Windows 2000 Server [desktop apps only] |
| Target Platform | Windows |
| Header | strmif.h (include Dshow.h) |
| Library | Strmiids.lib |