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Diffstat (limited to 'include/media/Visualizer.h')
| -rw-r--r-- | include/media/Visualizer.h | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/include/media/Visualizer.h b/include/media/Visualizer.h new file mode 100644 index 0000000..5d51de8 --- /dev/null +++ b/include/media/Visualizer.h @@ -0,0 +1,160 @@ +/* + * 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 <media/AudioEffect.h> +#include <media/EffectVisualizerApi.h> +#include <string.h> + +/** + * 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(int32_t priority = 0, + effect_callback_t cbf = 0, + void* user = 0, + int sessionId = 0); + + ~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); + + // 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; } + + // 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); + +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(); + virtual status_t readyToRun(); + virtual void onFirstRef(); + Visualizer& mReceiver; + Mutex mLock; + uint32_t mSleepTimeUs; + }; + + status_t doFft(uint8_t *fft, uint8_t *waveform); + void periodicCapture(); + uint32_t initCaptureSize(); + + Mutex mLock; + uint32_t mCaptureRate; + uint32_t mCaptureSize; + uint32_t mSampleRate; + capture_cbk_t mCaptureCallBack; + void *mCaptureCbkUser; + sp<CaptureThread> mCaptureThread; + uint32_t mCaptureFlags; + void *mFftTable; +}; + + +}; // namespace android + +#endif // ANDROID_MEDIA_VISUALIZER_H |