AudioResamplerCubic.cpp revision 54b6cfa9a9e5b861a9930af873580d6dc20f773c 
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#include <stdint.h>
18#include <string.h>
19#include <sys/types.h>
20#include <cutils/log.h>
21
22#include "AudioResampler.h"
23#include "AudioResamplerCubic.h"
24
25#define LOG_TAG "AudioSRC"
26
27namespace android {
28// ----------------------------------------------------------------------------
29
30void AudioResamplerCubic::init() {
31    memset(&left, 0, sizeof(state));
32    memset(&right, 0, sizeof(state));
33}
34
35void AudioResamplerCubic::resample(int32_t* out, size_t outFrameCount,
36        AudioBufferProvider* provider) {
37
38    // should never happen, but we overflow if it does
39    // LOG_ASSERT(outFrameCount < 32767);
40
41    // select the appropriate resampler
42    switch (mChannelCount) {
43    case 1:
44        resampleMono16(out, outFrameCount, provider);
45        break;
46    case 2:
47        resampleStereo16(out, outFrameCount, provider);
48        break;
49    }
50}
51
52void AudioResamplerCubic::resampleStereo16(int32_t* out, size_t outFrameCount,
53        AudioBufferProvider* provider) {
54
55    int32_t vl = mVolume[0];
56    int32_t vr = mVolume[1];
57
58    size_t inputIndex = mInputIndex;
59    uint32_t phaseFraction = mPhaseFraction;
60    uint32_t phaseIncrement = mPhaseIncrement;
61    size_t outputIndex = 0;
62    size_t outputSampleCount = outFrameCount * 2;
63
64    // fetch first buffer
65    if (mBuffer.raw == NULL) {
66        provider->getNextBuffer(&mBuffer);
67        if (mBuffer.raw == NULL)
68            return;
69        // LOGW("New buffer: offset=%p, frames=%dn", mBuffer.raw, mBuffer.frameCount);
70    }
71    int16_t *in = mBuffer.i16;
72
73    while (outputIndex < outputSampleCount) {
74        int32_t sample;
75        int32_t x;
76
77        // calculate output sample
78        x = phaseFraction >> kPreInterpShift;
79        out[outputIndex++] += vl * interp(&left, x);
80        out[outputIndex++] += vr * interp(&right, x);
81        // out[outputIndex++] += vr * in[inputIndex*2];
82
83        // increment phase
84        phaseFraction += phaseIncrement;
85        uint32_t indexIncrement = (phaseFraction >> kNumPhaseBits);
86        phaseFraction &= kPhaseMask;
87
88        // time to fetch another sample
89        while (indexIncrement--) {
90
91            inputIndex++;
92            if (inputIndex == mBuffer.frameCount) {
93                inputIndex = 0;
94                provider->releaseBuffer(&mBuffer);
95                provider->getNextBuffer(&mBuffer);
96                if (mBuffer.raw == NULL)
97                    goto save_state;  // ugly, but efficient
98                in = mBuffer.i16;
99                // LOGW("New buffer: offset=%p, frames=%d\n", mBuffer.raw, mBuffer.frameCount);
100            }
101
102            // advance sample state
103            advance(&left, in[inputIndex*2]);
104            advance(&right, in[inputIndex*2+1]);
105        }
106    }
107
108save_state:
109    // LOGW("Done: index=%d, fraction=%u", inputIndex, phaseFraction);
110    mInputIndex = inputIndex;
111    mPhaseFraction = phaseFraction;
112}
113
114void AudioResamplerCubic::resampleMono16(int32_t* out, size_t outFrameCount,
115        AudioBufferProvider* provider) {
116
117    int32_t vl = mVolume[0];
118    int32_t vr = mVolume[1];
119
120    size_t inputIndex = mInputIndex;
121    uint32_t phaseFraction = mPhaseFraction;
122    uint32_t phaseIncrement = mPhaseIncrement;
123    size_t outputIndex = 0;
124    size_t outputSampleCount = outFrameCount * 2;
125
126    // fetch first buffer
127    if (mBuffer.raw == NULL) {
128        provider->getNextBuffer(&mBuffer);
129        if (mBuffer.raw == NULL)
130            return;
131        // LOGW("New buffer: offset=%p, frames=%d\n", mBuffer.raw, mBuffer.frameCount);
132    }
133    int16_t *in = mBuffer.i16;
134
135    while (outputIndex < outputSampleCount) {
136        int32_t sample;
137        int32_t x;
138
139        // calculate output sample
140        x = phaseFraction >> kPreInterpShift;
141        sample = interp(&left, x);
142        out[outputIndex++] += vl * sample;
143        out[outputIndex++] += vr * sample;
144
145        // increment phase
146        phaseFraction += phaseIncrement;
147        uint32_t indexIncrement = (phaseFraction >> kNumPhaseBits);
148        phaseFraction &= kPhaseMask;
149
150        // time to fetch another sample
151        while (indexIncrement--) {
152
153            inputIndex++;
154            if (inputIndex == mBuffer.frameCount) {
155                inputIndex = 0;
156                provider->releaseBuffer(&mBuffer);
157                provider->getNextBuffer(&mBuffer);
158                if (mBuffer.raw == NULL)
159                    goto save_state;  // ugly, but efficient
160                // LOGW("New buffer: offset=%p, frames=%dn", mBuffer.raw, mBuffer.frameCount);
161                in = mBuffer.i16;
162            }
163
164            // advance sample state
165            advance(&left, in[inputIndex]);
166        }
167    }
168
169save_state:
170    // LOGW("Done: index=%d, fraction=%u", inputIndex, phaseFraction);
171    mInputIndex = inputIndex;
172    mPhaseFraction = phaseFraction;
173}
174
175// ----------------------------------------------------------------------------
176}
177; // namespace android
178
179