Source code of Windows XP (NT5)
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//--------------------------------------------------------------------------;
//
// File: decibels.cpp
//
// Copyright (c) 1995 - 1996 Microsoft Corporation. All Rights Reserved.
//
// Abstract:
//
// utilities for converting volume/pan in decibel units to/from
// the 0-0xffff (0-1000) range used by waveOutSetVolume (MCI) etc
//
// Contents:
//
// History:
// 06/15/95 SteveDav plagiarised from Direct Sound
//
//--------------------------------------------------------------------------;
#ifdef __cplusplus
extern "C" {
#endif // __cplusplus
#ifndef _AMOVIE_DB_
#define AMOVIEAPI_DB DECLSPEC_IMPORT
#else
#define AMOVIEAPI_DB
#endif
AMOVIEAPI_DB LONG WINAPI AmpFactorToDB( DWORD dwFactor );
AMOVIEAPI_DB DWORD WINAPI DBToAmpFactor( LONG lDB );
#ifdef __cplusplus
}
#endif // __cplusplus
#define AX_MIN_VOLUME -10000
#define AX_QUARTER_VOLUME -1200
#define AX_HALF_VOLUME -600
#define AX_THREEQUARTERS_VOLUME -240
#define AX_MAX_VOLUME 0
#define AX_BALANCE_LEFT -10000
#define AX_BALANCE_RIGHT 10000
#define AX_BALANCE_NEUTRAL 0