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Diffstat (limited to 'media/libeffects/lvm/lib/Common/src/LVC_Mixer_SetTimeConstant.c')
| -rwxr-xr-x | media/libeffects/lvm/lib/Common/src/LVC_Mixer_SetTimeConstant.c | 84 |
1 files changed, 84 insertions, 0 deletions
diff --git a/media/libeffects/lvm/lib/Common/src/LVC_Mixer_SetTimeConstant.c b/media/libeffects/lvm/lib/Common/src/LVC_Mixer_SetTimeConstant.c new file mode 100755 index 0000000..df0fd37 --- /dev/null +++ b/media/libeffects/lvm/lib/Common/src/LVC_Mixer_SetTimeConstant.c @@ -0,0 +1,84 @@ +/* + * Copyright (C) 2004-2010 NXP Software + * Copyright (C) 2010 The Android Open Source Project + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +/************************************************************************/ +/* */ +/* Project:: */ +/* $Author: beq07716 $*/ +/* $Revision: 1000 $*/ +/* $Date: 2010-06-28 13:08:20 +0200 (Mon, 28 Jun 2010) $*/ +/* */ +/************************************************************************/ + +#include "LVM_Types.h" +#include "LVM_Macros.h" +#include "LVC_Mixer_Private.h" + +/************************************************************************/ +/* FUNCTION: */ +/* LVMixer3_SetTimeConstant */ +/* */ +/* DESCRIPTION: */ +/* This function calculates the step change for fractional gain for a */ +/* given time constant, sample rate and num channels */ +/* Delta=(2147483647*4*1000)/(NumChannels*SampleRate*Tc_millisec) */ +/* in Q 0.31 format */ +/* */ +/* PARAMETERS: */ +/* pStream - ptr to Instance Parameter Structure LVMixer3_st for an*/ +/* Audio Stream */ +/* Tc_millisec - TimeConstant i.e time required in milli second to */ +/* go from linear fractional gain of 0 to 0.99999999 */ +/* Fs - LVM_Fs_en enumerator for Sampling Frequency */ +/* NumChannels - Number of channels in Audio Stream 1=Mono, 2=Stereo */ +/* */ +/* UPDATES: */ +/* Delta - the step change for fractional gain per 4 samples */ +/* in Q0.31 format for a given Time Constant, */ +/* Sample Rate and NumChannels */ +/* RETURNS: */ +/* void */ +/************************************************************************/ + +void LVC_Mixer_SetTimeConstant(LVMixer3_st *pStream, + LVM_INT32 Tc_millisec, + LVM_Fs_en Fs, + LVM_INT16 NumChannels) +{ + LVM_INT32 DeltaTable[9]={1073741824, + 779132389, + 715827882, + 536870912, + 389566194, + 357913941, + 268435456, + 194783097, + 178956971}; + Mix_Private_st *pInstance=(Mix_Private_st *)pStream->PrivateParams; + LVM_INT32 Delta=DeltaTable[Fs]; + Delta=Delta>>(NumChannels-1); + + if(Tc_millisec==0) + Delta=0x7FFFFFFF; + else + Delta=Delta/Tc_millisec; + + if(Delta==0) + Delta=1; // If Time Constant is so large that Delta is 0, assign minimum value to Delta + + pInstance->Delta=Delta; // Delta=(2147483647*4*1000)/(NumChannels*SampleRate*Tc_millisec) in Q 0.31 format +} |