/* * Copyright (C) 2010 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #ifndef ANDROID_MEDIA_VISUALIZER_H #define ANDROID_MEDIA_VISUALIZER_H #include #include #include /** * The Visualizer class enables application to retrieve part of the currently playing audio for * visualization purpose. It is not an audio recording interface and only returns partial and low * quality audio content. However, to protect privacy of certain audio data (e.g voice mail) the use * of the visualizer requires the permission android.permission.RECORD_AUDIO. * The audio session ID passed to the constructor indicates which audio content should be * visualized: * - If the session is 0, the audio output mix is visualized * - If the session is not 0, the audio from a particular MediaPlayer or AudioTrack * using this audio session is visualized * Two types of representation of audio content can be captured: * - Waveform data: consecutive 8-bit (unsigned) mono samples by using the getWaveForm() method * - Frequency data: 8-bit magnitude FFT by using the getFft() method * * The length of the capture can be retrieved or specified by calling respectively * getCaptureSize() and setCaptureSize() methods. Note that the size of the FFT * is half of the specified capture size but both sides of the spectrum are returned yielding in a * number of bytes equal to the capture size. The capture size must be a power of 2 in the range * returned by getMinCaptureSize() and getMaxCaptureSize(). * In addition to the polling capture mode, a callback mode is also available by installing a * callback function by use of the setCaptureCallBack() method. The rate at which the callback * is called as well as the type of data returned is specified. * Before capturing data, the Visualizer must be enabled by calling the setEnabled() method. * When data capture is not needed any more, the Visualizer should be disabled. */ namespace android { // ---------------------------------------------------------------------------- class Visualizer: public AudioEffect { public: enum callback_flags { CAPTURE_WAVEFORM = 0x00000001, // capture callback returns a PCM wave form CAPTURE_FFT = 0x00000002, // apture callback returns a frequency representation CAPTURE_CALL_JAVA = 0x00000004 // the callback thread can call java }; /* Constructor. * See AudioEffect constructor for details on parameters. */ Visualizer(const String16& opPackageName, int32_t priority = 0, effect_callback_t cbf = NULL, void* user = NULL, audio_session_t sessionId = AUDIO_SESSION_OUTPUT_MIX); ~Visualizer(); virtual status_t setEnabled(bool enabled); // maximum capture size in samples static uint32_t getMaxCaptureSize() { return VISUALIZER_CAPTURE_SIZE_MAX; } // minimum capture size in samples static uint32_t getMinCaptureSize() { return VISUALIZER_CAPTURE_SIZE_MIN; } // maximum capture rate in millihertz static uint32_t getMaxCaptureRate() { return CAPTURE_RATE_MAX; } // callback used to return periodic PCM or FFT captures to the application. Either one or both // types of data are returned (PCM and FFT) according to flags indicated when installing the // callback. When a type of data is not present, the corresponding size (waveformSize or // fftSize) is 0. typedef void (*capture_cbk_t)(void* user, uint32_t waveformSize, uint8_t *waveform, uint32_t fftSize, uint8_t *fft, uint32_t samplingrate); // install a callback to receive periodic captures. The capture rate is specified in milliHertz // and the capture format is according to flags (see callback_flags). status_t setCaptureCallBack(capture_cbk_t cbk, void* user, uint32_t flags, uint32_t rate, bool force = false); // set the capture size capture size must be a power of two in the range // [VISUALIZER_CAPTURE_SIZE_MAX. VISUALIZER_CAPTURE_SIZE_MIN] // must be called when the visualizer is not enabled status_t setCaptureSize(uint32_t size); uint32_t getCaptureSize() { return mCaptureSize; } // returns the capture rate indicated when installing the callback uint32_t getCaptureRate() { return mCaptureRate; } // returns the sampling rate of the audio being captured uint32_t getSamplingRate() { return mSampleRate; } // set the way volume affects the captured data // mode must one of VISUALIZER_SCALING_MODE_NORMALIZED, // VISUALIZER_SCALING_MODE_AS_PLAYED status_t setScalingMode(uint32_t mode); uint32_t getScalingMode() { return mScalingMode; } // set which measurements are done on the audio buffers processed by the effect. // valid measurements (mask): MEASUREMENT_MODE_PEAK_RMS status_t setMeasurementMode(uint32_t mode); uint32_t getMeasurementMode() { return mMeasurementMode; } // return a set of int32_t measurements status_t getIntMeasurements(uint32_t type, uint32_t number, int32_t *measurements); // return a capture in PCM 8 bit unsigned format. The size of the capture is equal to // getCaptureSize() status_t getWaveForm(uint8_t *waveform); // return a capture in FFT 8 bit signed format. The size of the capture is equal to // getCaptureSize() but the length of the FFT is half of the size (both parts of the spectrum // are returned status_t getFft(uint8_t *fft); protected: // from IEffectClient virtual void controlStatusChanged(bool controlGranted); private: static const uint32_t CAPTURE_RATE_MAX = 20000; static const uint32_t CAPTURE_RATE_DEF = 10000; static const uint32_t CAPTURE_SIZE_DEF = VISUALIZER_CAPTURE_SIZE_MAX; /* internal class to handle the callback */ class CaptureThread : public Thread { public: CaptureThread(Visualizer& receiver, uint32_t captureRate, bool bCanCallJava = false); private: friend class Visualizer; virtual bool threadLoop(); Visualizer& mReceiver; Mutex mLock; uint32_t mSleepTimeUs; }; status_t doFft(uint8_t *fft, uint8_t *waveform); void periodicCapture(); uint32_t initCaptureSize(); Mutex mCaptureLock; uint32_t mCaptureRate; uint32_t mCaptureSize; uint32_t mSampleRate; uint32_t mScalingMode; uint32_t mMeasurementMode; capture_cbk_t mCaptureCallBack; void *mCaptureCbkUser; sp mCaptureThread; uint32_t mCaptureFlags; }; }; // namespace android #endif // ANDROID_MEDIA_VISUALIZER_H