Visualizer.h revision a0d68338a88c2ddb4502f95017b546d603ef1ec7 
1/*
2 * Copyright (C) 2010 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_MEDIA_VISUALIZER_H
18#define ANDROID_MEDIA_VISUALIZER_H
19
20#include <media/AudioEffect.h>
21#include <audio_effects/effect_visualizer.h>
22#include <string.h>
23
24/**
25 * The Visualizer class enables application to retrieve part of the currently playing audio for
26 * visualization purpose. It is not an audio recording interface and only returns partial and low
27 * quality audio content. However, to protect privacy of certain audio data (e.g voice mail) the use
28 * of the visualizer requires the permission android.permission.RECORD_AUDIO.
29 * The audio session ID passed to the constructor indicates which audio content should be
30 * visualized:
31 * - If the session is 0, the audio output mix is visualized
32 * - If the session is not 0, the audio from a particular MediaPlayer or AudioTrack
33 *   using this audio session is visualized
34 * Two types of representation of audio content can be captured:
35 * - Waveform data: consecutive 8-bit (unsigned) mono samples by using the getWaveForm() method
36 * - Frequency data: 8-bit magnitude FFT by using the getFft() method
37 *
38 * The length of the capture can be retrieved or specified by calling respectively
39 * getCaptureSize() and setCaptureSize() methods. Note that the size of the FFT
40 * is half of the specified capture size but both sides of the spectrum are returned yielding in a
41 * number of bytes equal to the capture size. The capture size must be a power of 2 in the range
42 * returned by getMinCaptureSize() and getMaxCaptureSize().
43 * In addition to the polling capture mode, a callback mode is also available by installing a
44 * callback function by use of the setCaptureCallBack() method. The rate at which the callback
45 * is called as well as the type of data returned is specified.
46 * Before capturing data, the Visualizer must be enabled by calling the setEnabled() method.
47 * When data capture is not needed any more, the Visualizer should be disabled.
48 */
49
50
51namespace android {
52
53// ----------------------------------------------------------------------------
54
55class Visualizer: public AudioEffect {
56public:
57
58    enum callback_flags {
59        CAPTURE_WAVEFORM = 0x00000001,  // capture callback returns a PCM wave form
60        CAPTURE_FFT = 0x00000002,       // apture callback returns a frequency representation
61        CAPTURE_CALL_JAVA = 0x00000004  // the callback thread can call java
62    };
63
64
65    /* Constructor.
66     * See AudioEffect constructor for details on parameters.
67     */
68                        Visualizer(int32_t priority = 0,
69                                   effect_callback_t cbf = NULL,
70                                   void* user = NULL,
71                                   int sessionId = 0);
72
73                        ~Visualizer();
74
75    virtual status_t    setEnabled(bool enabled);
76
77    // maximum capture size in samples
78    static uint32_t getMaxCaptureSize() { return VISUALIZER_CAPTURE_SIZE_MAX; }
79    // minimum capture size in samples
80    static uint32_t getMinCaptureSize() { return VISUALIZER_CAPTURE_SIZE_MIN; }
81    // maximum capture rate in millihertz
82    static uint32_t getMaxCaptureRate() { return CAPTURE_RATE_MAX; }
83
84    // callback used to return periodic PCM or FFT captures to the application. Either one or both
85    // types of data are returned (PCM and FFT) according to flags indicated when installing the
86    // callback. When a type of data is not present, the corresponding size (waveformSize or
87    // fftSize) is 0.
88    typedef void (*capture_cbk_t)(void* user,
89                                    uint32_t waveformSize,
90                                    uint8_t *waveform,
91                                    uint32_t fftSize,
92                                    uint8_t *fft,
93                                    uint32_t samplingrate);
94
95    // install a callback to receive periodic captures. The capture rate is specified in milliHertz
96    // and the capture format is according to flags  (see callback_flags).
97    status_t setCaptureCallBack(capture_cbk_t cbk, void* user, uint32_t flags, uint32_t rate);
98
99    // set the capture size capture size must be a power of two in the range
100    // [VISUALIZER_CAPTURE_SIZE_MAX. VISUALIZER_CAPTURE_SIZE_MIN]
101    // must be called when the visualizer is not enabled
102    status_t setCaptureSize(uint32_t size);
103    uint32_t getCaptureSize() { return mCaptureSize; }
104
105    // returns the capture rate indicated when installing the callback
106    uint32_t getCaptureRate() { return mCaptureRate; }
107
108    // returns the sampling rate of the audio being captured
109    uint32_t getSamplingRate() { return mSampleRate; }
110
111    // return a capture in PCM 8 bit unsigned format. The size of the capture is equal to
112    // getCaptureSize()
113    status_t getWaveForm(uint8_t *waveform);
114
115    // return a capture in FFT 8 bit signed format. The size of the capture is equal to
116    // getCaptureSize() but the length of the FFT is half of the size (both parts of the spectrum
117    // are returned
118    status_t getFft(uint8_t *fft);
119
120private:
121
122    static const uint32_t CAPTURE_RATE_MAX = 20000;
123    static const uint32_t CAPTURE_RATE_DEF = 10000;
124    static const uint32_t CAPTURE_SIZE_DEF = VISUALIZER_CAPTURE_SIZE_MAX;
125
126    /* internal class to handle the callback */
127    class CaptureThread : public Thread
128    {
129    public:
130        CaptureThread(Visualizer& receiver, uint32_t captureRate, bool bCanCallJava = false);
131
132    private:
133        friend class Visualizer;
134        virtual bool        threadLoop();
135        virtual status_t    readyToRun();
136        virtual void        onFirstRef();
137        Visualizer& mReceiver;
138        Mutex       mLock;
139        uint32_t mSleepTimeUs;
140    };
141
142    status_t doFft(uint8_t *fft, uint8_t *waveform);
143    void periodicCapture();
144    uint32_t initCaptureSize();
145
146    Mutex mCaptureLock;
147    uint32_t mCaptureRate;
148    uint32_t mCaptureSize;
149    uint32_t mSampleRate;
150    capture_cbk_t mCaptureCallBack;
151    void *mCaptureCbkUser;
152    sp<CaptureThread> mCaptureThread;
153    uint32_t mCaptureFlags;
154};
155
156
157}; // namespace android
158
159#endif // ANDROID_MEDIA_VISUALIZER_H
160