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Commit fc2a0629 authored by Antti Lankila's avatar Antti Lankila
Browse files

Do headset filter in center+side audio space 

- Remove the slow integer division in the headset filter code, opting
  for more standard center+side channel calculation.
- Lay the groundwork for applying FIR-based directional emphasis
  filters. (No such filters are yet applied, however.)
- Reduce the delay line length in Haas effect to reduce audible
  ringing in the "Stage" mode.

Change-Id: If521af4c3a501be4f496de17ce179281fbd5b568
parent e2bf4809

media/libeffects/cyanogen-dsp/Android.mk

+1 −0
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ LOCAL_SRC_FILES := \ 
	EffectCompression.cpp \

	EffectEqualizer.cpp \

	EffectVirtualizer.cpp \

	FIR16.cpp \

# terminator



LOCAL_C_INCLUDES += \

media/libeffects/cyanogen-dsp/EffectVirtualizer.cpp

+39 −27
Original line number Diff line number Diff line
@@ -38,6 +38,27 @@ EffectVirtualizer::EffectVirtualizer() 
int32_t EffectVirtualizer::command(uint32_t cmdCode, uint32_t cmdSize, void* pCmdData, uint32_t* replySize, void* pReplyData)

{

    if (cmdCode == EFFECT_CMD_CONFIGURE) {

	/* Preliminary design -- needs more work.

	 * NOT ACTUALLY USED. */

	float fir44100[16] = {

		0.584375000000000,

		0.080172281918782,

		0.049463834764832,

		-0.015690873571518,

		-0.065625000000000,

		-0.045552813136128,

		0.031786165235168,

		0.106071404788864,

		0.134375000000000,

		0.106071404788864,

		0.031786165235168,

		-0.045552813136128,

		-0.065625000000000,

		-0.015690873571518,

		0.049463834764832,

		0.080172281918782

	};



	int32_t ret = Effect::configure(pCmdData);

	if (ret != 0) {

	    int32_t *replyData = (int32_t *) pReplyData;
@@ -45,13 +66,13 @@ int32_t EffectVirtualizer::command(uint32_t cmdCode, uint32_t cmdSize, void* pCm 
	    return 0;

	}



	mReverbDelayL.setParameters(mSamplingRate, 0.030f);

	mReverbDelayR.setParameters(mSamplingRate, 0.030f);

	/* Haas effect delay */

	mReverbDelayL.setParameters(mSamplingRate, 0.025f);

	mReverbDelayR.setParameters(mSamplingRate, 0.025f);

	/* Center channel forward direction adjustment filter. */

	mColorization.setParameters(fir44100);

	/* the -3 dB point is around 650 Hz, giving about 300 us to work with */

	mLocalizationL.setHighShelf(800.0f, mSamplingRate, -11.0f, 0.72f);

	mLocalizationR.setHighShelf(800.0f, mSamplingRate, -11.0f, 0.72f);

	/* Rockbox has a 0.3 ms delay line (13 samples at 44100 Hz), but

	 * I think it makes the whole effect sound pretty bad so I skipped it! */

	mLocalization.setHighShelf(800.0f, mSamplingRate, -11.0f, 0.72f);



	mDelayDataL = 0;

	mDelayDataR = 0;
@@ -152,28 +173,19 @@ int32_t EffectVirtualizer::process(audio_buffer_t* in, audio_buffer_t* out) 
        dataL += dryL;

        dataR += dryR;



        /* In matrix decoding, center channel is mixed at 0.7 and the main channel at 1.

         * It follows that the sum of them is 1.7, and the proportion of the main channel

         * must be 1 / 1.7, or about 6/10. Assuming it is so, 4/10 is the contribution

         * of center, and when 2 channels are combined, the scaler is 2/10 or 1/5.

         *

         * We could try to dynamically adjust this divisor based on cross-correlation

         * between left/right channels, which would allow us to recover a reasonable

         * estimate of the music's original center channel. */

        int32_t center = (dataL + dataR) / 5;

        int32_t directL = (dataL - center);

        int32_t directR = (dataR - center);



        /* We assume center channel reaches both ears with no coloration required.

         * We could also handle it differently at reverb stage... */



        /* Apply localization filter. */

        int32_t localizedL = mLocalizationL.process(directL);

        int32_t localizedR = mLocalizationR.process(directR);

        

        /* Mix difference between channels. dataX = directX + center. */

        write(out, i * 2, dataL + localizedR);

        write(out, i * 2 + 1, dataR + localizedL);

	/* Center channel. */

	int32_t center  = (dataL + dataR) >> 1;

	/* Direct radiation components. */

	int32_t side = (dataL - dataR) >> 1;



	/* Adjust derived center channel coloration to emphasize forward

	 * direction impression. (XXX: disabled until configurable). */

	//center = mColorization.process(center);

	/* Sound reaching ear from the opposite speaker */

	side -= mLocalization.process(side);

        

        write(out, i * 2, center + side);

        write(out, i * 2 + 1, center - side);

    }



    return mEnable ? 0 : -ENODATA;

media/libeffects/cyanogen-dsp/EffectVirtualizer.h

+3 −1
Original line number Diff line number Diff line
@@ -5,6 +5,7 @@ 
#include "Biquad.h"

#include "Delay.h"

#include "Effect.h"

#include "FIR16.h"



class EffectVirtualizer : public Effect {

    private:
@@ -15,7 +16,8 @@ class EffectVirtualizer : public Effect { 


    Delay mReverbDelayL, mReverbDelayR;

    int64_t mDelayDataL, mDelayDataR;

    Biquad mLocalizationL, mLocalizationR;

    FIR16 mColorization;

    Biquad mLocalization;



    void refreshStrength();

media/libeffects/cyanogen-dsp/FIR16.cpp

0 → 100644
+50 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2011 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.

 */



#include "FIR16.h"



#include <string.h>



FIR16::FIR16()

    : mIndex(0)

{

    memset(mState, 0, sizeof(mState));

    memset(mCoeff, 0, sizeof(mCoeff));

}



FIR16::~FIR16()

{

}



void FIR16::setParameters(float coeff[16])

{

    for (int32_t i = 0; i < 16; i ++) {

   	mCoeff[i] = int64_t(coeff[i] * (int64_t(1) << 32));

    }

}



int32_t FIR16::process(int32_t x0)

{

    mIndex --;

    mState[mIndex & 0xf] = x0;



    int64_t y = 0;

    for (int32_t i = 0; i < 16; i ++) {

	y += mCoeff[i] * mState[(i + mIndex) & 0xf];

    }



    return int32_t(y >> 32);

}

media/libeffects/cyanogen-dsp/FIR16.h

0 → 100644
+15 −0
Original line number Diff line number Diff line 
#pragma once



#include <stdint.h>



class FIR16 {

    int64_t mCoeff[16];

    int32_t mState[16];

    int32_t mIndex;



    public:

    FIR16();

    ~FIR16();

    void setParameters(float coeff[16]);

    int32_t process(int32_t x0);

};