1e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman/* 2e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman * Copyright (C) 2014 The Android Open Source Project 3e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman * 4e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman * Licensed under the Apache License, Version 2.0 (the "License"); 5e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman * you may not use this file except in compliance with the License. 6e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman * You may obtain a copy of the License at 7e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman * 8e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman * http://www.apache.org/licenses/LICENSE-2.0 9e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman * 10e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman * Unless required by applicable law or agreed to in writing, software 11e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman * distributed under the License is distributed on an "AS IS" BASIS, 12e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman * See the License for the specific language governing permissions and 14e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman * limitations under the License. 15e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman */ 16e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman 17e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman#ifndef ANDROID_AUDIO_RESAMPLER_PUBLIC_H 18e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman#define ANDROID_AUDIO_RESAMPLER_PUBLIC_H 19e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman 20e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman#include <stdint.h> 21e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman#include <math.h> 22e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman 23e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatramannamespace android { 24e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman 25e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// AUDIO_RESAMPLER_DOWN_RATIO_MAX is the maximum ratio between the original 26e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// audio sample rate and the target rate when downsampling, 27e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// as permitted in the audio framework, e.g. AudioTrack and AudioFlinger. 28e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// In practice, it is not recommended to downsample more than 6:1 29e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// for best audio quality, even though the audio framework permits a larger 30e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// downsampling ratio. 31e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// TODO: replace with an API 32e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman#define AUDIO_RESAMPLER_DOWN_RATIO_MAX 256 33e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman 34e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// AUDIO_RESAMPLER_UP_RATIO_MAX is the maximum suggested ratio between the original 35e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// audio sample rate and the target rate when upsampling. It is loosely enforced by 36e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// the system. One issue with large upsampling ratios is the approximation by 37e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// an int32_t of the phase increments, making the resulting sample rate inexact. 38e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman#define AUDIO_RESAMPLER_UP_RATIO_MAX 65536 39e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman 40e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// AUDIO_TIMESTRETCH_SPEED_MIN and AUDIO_TIMESTRETCH_SPEED_MAX define the min and max time stretch 41e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// speeds supported by the system. These are enforced by the system and values outside this range 42e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// will result in a runtime error. 43e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// Depending on the AudioPlaybackRate::mStretchMode, the effective limits might be narrower than 44e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// the ones specified here 45e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// AUDIO_TIMESTRETCH_SPEED_MIN_DELTA is the minimum absolute speed difference that might trigger a 46e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// parameter update 47e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman#define AUDIO_TIMESTRETCH_SPEED_MIN 0.01f 48e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman#define AUDIO_TIMESTRETCH_SPEED_MAX 20.0f 49e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman#define AUDIO_TIMESTRETCH_SPEED_NORMAL 1.0f 50e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman#define AUDIO_TIMESTRETCH_SPEED_MIN_DELTA 0.0001f 51e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman 52e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// AUDIO_TIMESTRETCH_PITCH_MIN and AUDIO_TIMESTRETCH_PITCH_MAX define the min and max time stretch 53e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// pitch shifting supported by the system. These are not enforced by the system and values 54e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// outside this range might result in a pitch different than the one requested. 55e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// Depending on the AudioPlaybackRate::mStretchMode, the effective limits might be narrower than 56e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// the ones specified here. 57e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// AUDIO_TIMESTRETCH_PITCH_MIN_DELTA is the minimum absolute pitch difference that might trigger a 58e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// parameter update 59e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman#define AUDIO_TIMESTRETCH_PITCH_MIN 0.25f 60e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman#define AUDIO_TIMESTRETCH_PITCH_MAX 4.0f 61e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman#define AUDIO_TIMESTRETCH_PITCH_NORMAL 1.0f 62e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman#define AUDIO_TIMESTRETCH_PITCH_MIN_DELTA 0.0001f 63e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman 64e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman 65e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman//Determines the current algorithm used for stretching 66e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatramanenum AudioTimestretchStretchMode : int32_t { 67e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman AUDIO_TIMESTRETCH_STRETCH_DEFAULT = 0, 68e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman AUDIO_TIMESTRETCH_STRETCH_SPEECH = 1, 69e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman //TODO: add more stretch modes/algorithms 70e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman}; 71e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman 72e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman//Limits for AUDIO_TIMESTRETCH_STRETCH_SPEECH mode 73e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman#define TIMESTRETCH_SONIC_SPEED_MIN 0.1f 74e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman#define TIMESTRETCH_SONIC_SPEED_MAX 6.0f 75e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman 76e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman//Determines behavior of Timestretch if current algorithm can't perform 77e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman//with current parameters. 78e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// FALLBACK_CUT_REPEAT: (internal only) for speed <1.0 will truncate frames 79e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// for speed > 1.0 will repeat frames 80e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// FALLBACK_MUTE: will set all processed frames to zero 81e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// FALLBACK_FAIL: will stop program execution and log a fatal error 82e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatramanenum AudioTimestretchFallbackMode : int32_t { 83e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman AUDIO_TIMESTRETCH_FALLBACK_CUT_REPEAT = -1, 84e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman AUDIO_TIMESTRETCH_FALLBACK_DEFAULT = 0, 85e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman AUDIO_TIMESTRETCH_FALLBACK_MUTE = 1, 86e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman AUDIO_TIMESTRETCH_FALLBACK_FAIL = 2, 87e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman}; 88e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman 89e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatramanstruct AudioPlaybackRate { 90e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman float mSpeed; 91e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman float mPitch; 92e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman enum AudioTimestretchStretchMode mStretchMode; 93e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman enum AudioTimestretchFallbackMode mFallbackMode; 94e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman}; 95e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman 96e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatramanstatic const AudioPlaybackRate AUDIO_PLAYBACK_RATE_DEFAULT = { 97e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman AUDIO_TIMESTRETCH_SPEED_NORMAL, 98e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman AUDIO_TIMESTRETCH_PITCH_NORMAL, 99e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman AUDIO_TIMESTRETCH_STRETCH_DEFAULT, 100e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman AUDIO_TIMESTRETCH_FALLBACK_DEFAULT 101e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman}; 102e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman 103e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatramanstatic inline bool isAudioPlaybackRateEqual(const AudioPlaybackRate &pr1, 104e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman const AudioPlaybackRate &pr2) { 105e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman return fabs(pr1.mSpeed - pr2.mSpeed) < AUDIO_TIMESTRETCH_SPEED_MIN_DELTA && 106e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman fabs(pr1.mPitch - pr2.mPitch) < AUDIO_TIMESTRETCH_PITCH_MIN_DELTA && 107e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman pr2.mStretchMode == pr2.mStretchMode && 108e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman pr2.mFallbackMode == pr2.mFallbackMode; 109e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman} 110e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman 111e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatramanstatic inline bool isAudioPlaybackRateValid(const AudioPlaybackRate &playbackRate) { 112e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman if (playbackRate.mFallbackMode == AUDIO_TIMESTRETCH_FALLBACK_FAIL && 113e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman (playbackRate.mStretchMode == AUDIO_TIMESTRETCH_STRETCH_SPEECH || 114e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman playbackRate.mStretchMode == AUDIO_TIMESTRETCH_STRETCH_DEFAULT)) { 115e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman //test sonic specific constraints 116e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman return playbackRate.mSpeed >= TIMESTRETCH_SONIC_SPEED_MIN && 117e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman playbackRate.mSpeed <= TIMESTRETCH_SONIC_SPEED_MAX && 118e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman playbackRate.mPitch >= AUDIO_TIMESTRETCH_PITCH_MIN && 119e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman playbackRate.mPitch <= AUDIO_TIMESTRETCH_PITCH_MAX; 120e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman } else { 121e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman return playbackRate.mSpeed >= AUDIO_TIMESTRETCH_SPEED_MIN && 122e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman playbackRate.mSpeed <= AUDIO_TIMESTRETCH_SPEED_MAX && 123e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman playbackRate.mPitch >= AUDIO_TIMESTRETCH_PITCH_MIN && 124e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman playbackRate.mPitch <= AUDIO_TIMESTRETCH_PITCH_MAX; 125e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman } 126e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman} 127e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman 128e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// TODO: Consider putting these inlines into a class scope 129e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman 130e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// Returns the source frames needed to resample to destination frames. This is not a precise 131e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// value and depends on the resampler (and possibly how it handles rounding internally). 132e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// Nevertheless, this should be an upper bound on the requirements of the resampler. 133e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// If srcSampleRate and dstSampleRate are equal, then it returns destination frames, which 134e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// may not be true if the resampler is asynchronous. 135e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatramanstatic inline size_t sourceFramesNeeded( 136e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman uint32_t srcSampleRate, size_t dstFramesRequired, uint32_t dstSampleRate) { 137e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman // +1 for rounding - always do this even if matched ratio (resampler may use phases not ratio) 138e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman // +1 for additional sample needed for interpolation 139e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman return srcSampleRate == dstSampleRate ? dstFramesRequired : 140e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman size_t((uint64_t)dstFramesRequired * srcSampleRate / dstSampleRate + 1 + 1); 141e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman} 142e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman 143e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// An upper bound for the number of destination frames possible from srcFrames 144e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// after sample rate conversion. This may be used for buffer sizing. 145e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatramanstatic inline size_t destinationFramesPossible(size_t srcFrames, uint32_t srcSampleRate, 146e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman uint32_t dstSampleRate) { 147e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman if (srcSampleRate == dstSampleRate) { 148e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman return srcFrames; 149e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman } 150e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman uint64_t dstFrames = (uint64_t)srcFrames * dstSampleRate / srcSampleRate; 151e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman return dstFrames > 2 ? dstFrames - 2 : 0; 152e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman} 153e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman 154e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatramanstatic inline size_t sourceFramesNeededWithTimestretch( 155e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman uint32_t srcSampleRate, size_t dstFramesRequired, uint32_t dstSampleRate, 156e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman float speed) { 157e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman // required is the number of input frames the resampler needs 158e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman size_t required = sourceFramesNeeded(srcSampleRate, dstFramesRequired, dstSampleRate); 159e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman // to deliver this, the time stretcher requires: 160e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman return required * (double)speed + 1 + 1; // accounting for rounding dependencies 161e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman} 162e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman 163e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// Identifies sample rates that we associate with music 164e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// and thus eligible for better resampling and fast capture. 165e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// This is somewhat less than 44100 to allow for pitch correction 166e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// involving resampling as well as asynchronous resampling. 167e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman#define AUDIO_PROCESSING_MUSIC_RATE 40000 168e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman 169e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatramanstatic inline bool isMusicRate(uint32_t sampleRate) { 170e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman return sampleRate >= AUDIO_PROCESSING_MUSIC_RATE; 171e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman} 172e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman 173e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman} // namespace android 174e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman 175e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman// --------------------------------------------------------------------------- 176e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman 177e2b43843fd12783188edd2c54188ea8d26864788Vijay Venkatraman#endif // ANDROID_AUDIO_RESAMPLER_PUBLIC_H 178