1 /* 2 * Copyright (C) 2016 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_AAUDIO_ISOCHRONOUS_CLOCK_MODEL_H 18 #define ANDROID_AAUDIO_ISOCHRONOUS_CLOCK_MODEL_H 19 20 #include <stdint.h> 21 22 namespace aaudio { 23 24 /** 25 * Model an isochronous data stream using occasional timestamps as input. 26 * This can be used to predict the position of the stream at a given time. 27 * 28 * This class is not thread safe and should only be called from one thread. 29 */ 30 class IsochronousClockModel { 31 32 public: 33 IsochronousClockModel(); 34 virtual ~IsochronousClockModel(); 35 36 void start(int64_t nanoTime); 37 void stop(int64_t nanoTime); 38 39 bool isStarting(); 40 41 void processTimestamp(int64_t framePosition, int64_t nanoTime); 42 43 /** 44 * @param sampleRate rate of the stream in frames per second 45 */ 46 void setSampleRate(int32_t sampleRate); 47 48 void setPositionAndTime(int64_t framePosition, int64_t nanoTime); 49 getSampleRate()50 int32_t getSampleRate() const { 51 return mSampleRate; 52 } 53 54 /** 55 * This must be set accurately in order to track the isochronous stream. 56 * 57 * @param framesPerBurst number of frames that stream advance at one time. 58 */ 59 void setFramesPerBurst(int32_t framesPerBurst); 60 getFramesPerBurst()61 int32_t getFramesPerBurst() const { 62 return mFramesPerBurst; 63 } 64 65 /** 66 * Calculate an estimated time when the stream will be at that position. 67 * 68 * @param framePosition position of the stream in frames 69 * @return time in nanoseconds 70 */ 71 int64_t convertPositionToTime(int64_t framePosition) const; 72 73 /** 74 * Calculate an estimated position where the stream will be at the specified time. 75 * 76 * @param nanoTime time of interest 77 * @return position in frames 78 */ 79 int64_t convertTimeToPosition(int64_t nanoTime) const; 80 81 /** 82 * @param framesDelta difference in frames 83 * @return duration in nanoseconds 84 */ 85 int64_t convertDeltaPositionToTime(int64_t framesDelta) const; 86 87 /** 88 * @param nanosDelta duration in nanoseconds 89 * @return frames that stream will advance in that time 90 */ 91 int64_t convertDeltaTimeToPosition(int64_t nanosDelta) const; 92 93 void dump() const; 94 95 private: 96 enum clock_model_state_t { 97 STATE_STOPPED, 98 STATE_STARTING, 99 STATE_SYNCING, 100 STATE_RUNNING 101 }; 102 103 int64_t mMarkerFramePosition; 104 int64_t mMarkerNanoTime; 105 int32_t mSampleRate; 106 int32_t mFramesPerBurst; 107 int32_t mMaxLatenessInNanos; 108 clock_model_state_t mState; 109 110 void update(); 111 }; 112 113 } /* namespace aaudio */ 114 115 #endif //ANDROID_AAUDIO_ISOCHRONOUS_CLOCK_MODEL_H 116