1/*
2 * Copyright (C) 2007 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_H
18#define ANDROID_AUDIO_RESAMPLER_H
19
20#include <stdint.h>
21#include <sys/types.h>
22
23#include <media/AudioBufferProvider.h>
24
25namespace android {
26// ----------------------------------------------------------------------------
27
28class AudioResampler {
29public:
30    // Determines quality of SRC.
31    //  LOW_QUALITY: linear interpolator (1st order)
32    //  MED_QUALITY: cubic interpolator (3rd order)
33    //  HIGH_QUALITY: fixed multi-tap FIR (e.g. 48KHz->44.1KHz)
34    // NOTE: high quality SRC will only be supported for
35    // certain fixed rate conversions. Sample rate cannot be
36    // changed dynamically.
37    enum src_quality {
38        DEFAULT_QUALITY=0,
39        LOW_QUALITY=1,
40        MED_QUALITY=2,
41        HIGH_QUALITY=3,
42        VERY_HIGH_QUALITY=4,
43    };
44
45    static AudioResampler* create(int bitDepth, int inChannelCount,
46            int32_t sampleRate, src_quality quality=DEFAULT_QUALITY);
47
48    virtual ~AudioResampler();
49
50    virtual void init() = 0;
51    virtual void setSampleRate(int32_t inSampleRate);
52    virtual void setVolume(int16_t left, int16_t right);
53    virtual void setLocalTimeFreq(uint64_t freq);
54
55    // set the PTS of the next buffer output by the resampler
56    virtual void setPTS(int64_t pts);
57
58    virtual void resample(int32_t* out, size_t outFrameCount,
59            AudioBufferProvider* provider) = 0;
60
61    virtual void reset();
62    virtual size_t getUnreleasedFrames() const { return mInputIndex; }
63
64    // called from destructor, so must not be virtual
65    src_quality getQuality() const { return mQuality; }
66
67protected:
68    // number of bits for phase fraction - 30 bits allows nearly 2x downsampling
69    static const int kNumPhaseBits = 30;
70
71    // phase mask for fraction
72    static const uint32_t kPhaseMask = (1LU<<kNumPhaseBits)-1;
73
74    // multiplier to calculate fixed point phase increment
75    static const double kPhaseMultiplier = 1L << kNumPhaseBits;
76
77    AudioResampler(int bitDepth, int inChannelCount, int32_t sampleRate, src_quality quality);
78
79    // prevent copying
80    AudioResampler(const AudioResampler&);
81    AudioResampler& operator=(const AudioResampler&);
82
83    int64_t calculateOutputPTS(int outputFrameIndex);
84
85    const int32_t mBitDepth;
86    const int32_t mChannelCount;
87    const int32_t mSampleRate;
88    int32_t mInSampleRate;
89    AudioBufferProvider::Buffer mBuffer;
90    union {
91        int16_t mVolume[2];
92        uint32_t mVolumeRL;
93    };
94    int16_t mTargetVolume[2];
95    size_t mInputIndex;
96    int32_t mPhaseIncrement;
97    uint32_t mPhaseFraction;
98    uint64_t mLocalTimeFreq;
99    int64_t mPTS;
100
101private:
102    const src_quality mQuality;
103
104    // Return 'true' if the quality level is supported without explicit request
105    static bool qualityIsSupported(src_quality quality);
106
107    // For pthread_once()
108    static void init_routine();
109
110    // Return the estimated CPU load for specific resampler in MHz.
111    // The absolute number is irrelevant, it's the relative values that matter.
112    static uint32_t qualityMHz(src_quality quality);
113};
114
115// ----------------------------------------------------------------------------
116}
117; // namespace android
118
119#endif // ANDROID_AUDIO_RESAMPLER_H
120