160 lines
6.5 KiB
C++
160 lines
6.5 KiB
C++
/*
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* Copyright (C) 2010 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef ANDROID_MEDIA_VISUALIZER_H
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#define ANDROID_MEDIA_VISUALIZER_H
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#include <media/AudioEffect.h>
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#include <media/EffectVisualizerApi.h>
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#include <string.h>
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/**
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* The Visualizer class enables application to retrieve part of the currently playing audio for
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* visualization purpose. It is not an audio recording interface and only returns partial and low
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* quality audio content. However, to protect privacy of certain audio data (e.g voice mail) the use
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* of the visualizer requires the permission android.permission.RECORD_AUDIO.
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* The audio session ID passed to the constructor indicates which audio content should be
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* visualized:
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* - If the session is 0, the audio output mix is visualized
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* - If the session is not 0, the audio from a particular MediaPlayer or AudioTrack
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* using this audio session is visualized
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* Two types of representation of audio content can be captured:
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* - Waveform data: consecutive 8-bit (unsigned) mono samples by using the getWaveForm() method
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* - Frequency data: 8-bit magnitude FFT by using the getFft() method
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*
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* The length of the capture can be retrieved or specified by calling respectively
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* getCaptureSize() and setCaptureSize() methods. Note that the size of the FFT
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* is half of the specified capture size but both sides of the spectrum are returned yielding in a
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* number of bytes equal to the capture size. The capture size must be a power of 2 in the range
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* returned by getMinCaptureSize() and getMaxCaptureSize().
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* In addition to the polling capture mode, a callback mode is also available by installing a
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* callback function by use of the setCaptureCallBack() method. The rate at which the callback
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* is called as well as the type of data returned is specified.
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* Before capturing data, the Visualizer must be enabled by calling the setEnabled() method.
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* When data capture is not needed any more, the Visualizer should be disabled.
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*/
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namespace android {
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// ----------------------------------------------------------------------------
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class Visualizer: public AudioEffect {
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public:
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enum callback_flags {
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CAPTURE_WAVEFORM = 0x00000001, // capture callback returns a PCM wave form
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CAPTURE_FFT = 0x00000002, // apture callback returns a frequency representation
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CAPTURE_CALL_JAVA = 0x00000004 // the callback thread can call java
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};
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/* Constructor.
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* See AudioEffect constructor for details on parameters.
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*/
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Visualizer(int32_t priority = 0,
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effect_callback_t cbf = 0,
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void* user = 0,
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int sessionId = 0);
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~Visualizer();
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virtual status_t setEnabled(bool enabled);
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// maximum capture size in samples
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static uint32_t getMaxCaptureSize() { return VISUALIZER_CAPTURE_SIZE_MAX; }
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// minimum capture size in samples
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static uint32_t getMinCaptureSize() { return VISUALIZER_CAPTURE_SIZE_MIN; }
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// maximum capture rate in millihertz
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static uint32_t getMaxCaptureRate() { return CAPTURE_RATE_MAX; }
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// callback used to return periodic PCM or FFT captures to the application. Either one or both
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// types of data are returned (PCM and FFT) according to flags indicated when installing the
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// callback. When a type of data is not present, the corresponding size (waveformSize or
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// fftSize) is 0.
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typedef void (*capture_cbk_t)(void* user,
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uint32_t waveformSize,
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uint8_t *waveform,
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uint32_t fftSize,
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uint8_t *fft,
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uint32_t samplingrate);
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// install a callback to receive periodic captures. The capture rate is specified in milliHertz
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// and the capture format is according to flags (see callback_flags).
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status_t setCaptureCallBack(capture_cbk_t cbk, void* user, uint32_t flags, uint32_t rate);
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// set the capture size capture size must be a power of two in the range
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// [VISUALIZER_CAPTURE_SIZE_MAX. VISUALIZER_CAPTURE_SIZE_MIN]
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// must be called when the visualizer is not enabled
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status_t setCaptureSize(uint32_t size);
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uint32_t getCaptureSize() { return mCaptureSize; }
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// returns the capture rate indicated when installing the callback
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uint32_t getCaptureRate() { return mCaptureRate; }
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// returns the sampling rate of the audio being captured
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uint32_t getSamplingRate() { return mSampleRate; }
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// return a capture in PCM 8 bit unsigned format. The size of the capture is equal to
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// getCaptureSize()
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status_t getWaveForm(uint8_t *waveform);
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// return a capture in FFT 8 bit signed format. The size of the capture is equal to
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// getCaptureSize() but the length of the FFT is half of the size (both parts of the spectrum
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// are returned
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status_t getFft(uint8_t *fft);
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private:
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static const uint32_t CAPTURE_RATE_MAX = 20000;
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static const uint32_t CAPTURE_RATE_DEF = 10000;
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static const uint32_t CAPTURE_SIZE_DEF = VISUALIZER_CAPTURE_SIZE_MAX;
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/* internal class to handle the callback */
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class CaptureThread : public Thread
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{
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public:
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CaptureThread(Visualizer& receiver, uint32_t captureRate, bool bCanCallJava = false);
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private:
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friend class Visualizer;
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virtual bool threadLoop();
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virtual status_t readyToRun();
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virtual void onFirstRef();
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Visualizer& mReceiver;
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Mutex mLock;
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uint32_t mSleepTimeUs;
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};
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status_t doFft(uint8_t *fft, uint8_t *waveform);
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void periodicCapture();
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uint32_t initCaptureSize();
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Mutex mLock;
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uint32_t mCaptureRate;
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uint32_t mCaptureSize;
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uint32_t mSampleRate;
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capture_cbk_t mCaptureCallBack;
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void *mCaptureCbkUser;
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sp<CaptureThread> mCaptureThread;
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uint32_t mCaptureFlags;
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};
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}; // namespace android
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#endif // ANDROID_MEDIA_VISUALIZER_H
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