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IAMTVTuner::AutoTune

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Microsoft DirectShow 9.0

IAMTVTuner::AutoTune

The AutoTune method scans for a precise signal on the channel's frequency.

Syntax

  HRESULT AutoTune(
  long lChannel,
  long *plFoundSignal
);

Parameters

lChannel

[in] TV channel number.

plFoundSignal

[out] Pointer to a variable indicating whether the channel's frequency was found; nonzero indicates found, zero indicates not found.

Return Values

Returns an HRESULT value that depends on the implementation of the interface.

Remarks

TV channels generally map to a unique frequency depending on regional variances. To avoid interference between multiple transmitters that are assigned the same channel when they are in close geographic proximity, small frequency offsets are introduced at each transmitter. In the United States, this offset ranges up to +/– 26.25 kilohertz (kHz).

This method handles the channel-to-frequency conversion and scans for the most precise frequency. Store these values by calling the IAMTVTuner::StoreAutoTune method. You can find base frequencies for channels in the appendix International Analog TV Tuning.

Requirements

Header: Declared in Strmif.h; include Dshow.h.

Library: Use Strmiids.lib.

See Also