AudioResamplerDyn.h revision 771386e6e6e79697e2d839ef0f25a242946ba1e5 
1/*
2 * Copyright (C) 2013 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef ANDROID_AUDIO_RESAMPLER_DYN_H
18#define ANDROID_AUDIO_RESAMPLER_DYN_H
19
20#include <stdint.h>
21#include <sys/types.h>
22#include <cutils/log.h>
23
24#include "AudioResampler.h"
25
26namespace android {
27
28/* AudioResamplerDyn
29 *
30 * This class template is used for floating point and integer resamplers.
31 *
32 * Type variables:
33 * TC = filter coefficient type (one of int16_t, int32_t, or float)
34 * TI = input data type (one of int16_t or float)
35 * TO = output data type (one of int32_t or float)
36 *
37 * For integer input data types TI, the coefficient type TC is either int16_t or int32_t.
38 * For float input data types TI, the coefficient type TC is float.
39 */
40
41template<typename TC, typename TI, typename TO>
42class AudioResamplerDyn: public AudioResampler {
43public:
44    AudioResamplerDyn(int bitDepth, int inChannelCount,
45            int32_t sampleRate, src_quality quality);
46
47    virtual ~AudioResamplerDyn();
48
49    virtual void init();
50
51    virtual void setSampleRate(int32_t inSampleRate);
52
53    virtual void setVolume(int16_t left, int16_t right);
54
55    virtual void resample(int32_t* out, size_t outFrameCount,
56            AudioBufferProvider* provider);
57
58private:
59
60    class Constants { // stores the filter constants.
61    public:
62        Constants() :
63            mL(0), mShift(0), mHalfNumCoefs(0), mFirCoefs(NULL)
64        {}
65        void set(int L, int halfNumCoefs,
66                int inSampleRate, int outSampleRate);
67
68                 int mL;            // interpolation phases in the filter.
69                 int mShift;        // right shift to get polyphase index
70        unsigned int mHalfNumCoefs; // filter half #coefs
71           const TC* mFirCoefs;     // polyphase filter bank
72    };
73
74    class InBuffer { // buffer management for input type TI
75    public:
76        InBuffer();
77        ~InBuffer();
78        void init();
79
80        void resize(int CHANNELS, int halfNumCoefs);
81
82        // used for direct management of the mImpulse pointer
83        inline TI* getImpulse() {
84            return mImpulse;
85        }
86
87        inline void setImpulse(TI *impulse) {
88            mImpulse = impulse;
89        }
90
91        template<int CHANNELS>
92        inline void readAgain(TI*& impulse, const int halfNumCoefs,
93                const TI* const in, const size_t inputIndex);
94
95        template<int CHANNELS>
96        inline void readAdvance(TI*& impulse, const int halfNumCoefs,
97                const TI* const in, const size_t inputIndex);
98
99    private:
100        // tuning parameter guidelines: 2 <= multiple <= 8
101        static const int kStateSizeMultipleOfFilterLength = 4;
102
103        // in general, mRingFull = mState + mStateSize - halfNumCoefs*CHANNELS.
104           TI* mState;      // base pointer for the input buffer storage
105           TI* mImpulse;    // current location of the impulse response (centered)
106           TI* mRingFull;   // mState <= mImpulse < mRingFull
107        size_t mStateCount; // size of state in units of TI.
108    };
109
110    void createKaiserFir(Constants &c, double stopBandAtten,
111            int inSampleRate, int outSampleRate, double tbwCheat);
112
113    void setResampler(unsigned resampleType);
114
115    template<int CHANNELS, bool LOCKED, int STRIDE>
116    void resample(TO* out, size_t outFrameCount, AudioBufferProvider* provider);
117
118    // declare a pointer to member function for resample
119    typedef void (AudioResamplerDyn<TC, TI, TO>::*resample_ABP_t)(TO* out,
120            size_t outFrameCount, AudioBufferProvider* provider);
121
122    // data - the contiguous storage and layout of these is important.
123           InBuffer mInBuffer;
124          Constants mConstants;        // current set of coefficient parameters
125    TO __attribute__ ((aligned (8))) mVolumeSimd[2]; // must be aligned or NEON may crash
126     resample_ABP_t mResampleFunc;     // called function for resampling
127            int32_t mFilterSampleRate; // designed filter sample rate.
128        src_quality mFilterQuality;    // designed filter quality.
129              void* mCoefBuffer;       // if a filter is created, this is not null
130};
131
132}; // namespace android
133
134#endif /*ANDROID_AUDIO_RESAMPLER_DYN_H*/
135