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AudioPlayer.m
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AudioPlayer.m
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//
// AudioPlayer.m
// LoopMusic
//
// Created by Cheng Hann Gan on 5/9/16.
// Copyright © 2016 Cheng Hann Gan. All rights reserved.
//
#import <Foundation/Foundation.h>
#import "AudioPlayer.h"
/// The number of frames that have to match for the loop finder to accept a time.
static const UInt32 NUMMATCHINGFRAMES = 1;
/// The range of the loop finder's search.
static const float SEARCHRANGE = 1;
/// The tolerance of the loop finder's search.
static const float SEARCHTOLERANCE = 300;
@implementation AudioPlayer
@synthesize pauseTime;
- (id)init
{
self = [super init];
_audioController = [[AEAudioController alloc] initWithAudioDescription:AEAudioStreamBasicDescriptionNonInterleaved16BitStereo
inputEnabled:false];
_audioController.automaticLatencyManagement = false;
/// Holds error messages that may occur during audio controller initialization.
NSError *error;
bool result = [_audioController start:&error];
if (!result)
{
NSLog(@"%@", [error description]);
}
pauseTime = 0;
[self resetLoopCounter];
[self startFreeTimer];
return self;
}
/*!
* Starts the free timer if it isn't already started.
*/
- (void)startFreeTimer
{
if (!freeTimer)
{
freeTimer = [NSTimer scheduledTimerWithTimeInterval:0.5
target:self
selector:@selector(checkFree:)
userInfo:nil
repeats:YES];
}
}
/*!
* Checks if memory can be freed.
* @param timer The timer that called this function.
*/
- (void)checkFree:(NSTimer *)timer
{
if (freeData)
{
for (int i = 0; i < 2; i++)
{
free(freeData->playingList->mBuffers[i].mData);
}
free(freeData->playingList);
free(freeData);
freeData = nil;
}
if (!_playing)
{
[freeTimer invalidate];
freeTimer = nil;
}
}
- (NSTimeInterval)currentTime
{
return _playing ? audioData->currentFrame / (NSTimeInterval)FRAMERATE : pauseTime;
}
- (void)setCurrentTime:(NSTimeInterval)currentTime
{
NSInteger lastFrame = audioData ? (NSInteger)audioData->numFrames - 1 : 0;
bufferAudioData->currentFrame = MAX(0, MIN(lastFrame, round(currentTime * FRAMERATE)));
}
- (float)volume
{
return fminf(_volume * _globalVolume, 1);
}
- (void)setVolume:(float)volume
{
if (volume < 0)
{
volume = 0;
}
_volume = volume;
}
- (void)decrementVolume:(float)volumeDec
{
[self setVolume:_volume - volumeDec];
}
- (void)setGlobalVolume:(float)globalVolume
{
if (globalVolume < 0)
{
globalVolume = 0;
}
_globalVolume = globalVolume;
}
- (bool)playing
{
return _playing;
}
- (UInt32)frameDuration
{
return bufferAudioData->numFrames;
}
- (double)duration
{
return bufferAudioData->numFrames / (NSTimeInterval)FRAMERATE;
}
- (UInt32)loopStartFrame
{
return _loopStart;
}
- (NSTimeInterval)loopStart
{
return [AudioPlayer frameToTime:_loopStart];
}
- (void)setLoopStart:(NSTimeInterval)loopStart
{
_loopStart = [AudioPlayer timeToFrame:loopStart];
}
- (UInt32)loopEndFrame
{
return _loopEnd;
}
- (NSTimeInterval)loopEnd
{
return [AudioPlayer frameToTime:_loopEnd];
}
- (void)setLoopEnd:(NSTimeInterval)loopEnd
{
_loopEnd = [AudioPlayer timeToFrame:loopEnd];
}
- (bool)loading
{
return audioData->loading;
}
- (void)setLoading:(bool)loading
{
if (audioData)
{
audioData->loading = loading;
}
}
- (void)play
{
_playing = true;
if ([self numChannels] == 0)
{
[_audioController addChannels:@[_blockChannel]];
}
[self startFreeTimer];
self.currentTime = pauseTime;
}
/*!
*Stops playback of the audio player.
*/
- (void)stopPlayback
{
_playing = false;
if ([self numChannels] > 0)
{
[_audioController removeChannels:@[_blockChannel]];
}
}
- (void)pause
{
pauseTime = self.currentTime;
[self stopPlayback];
}
- (void)stop
{
pauseTime = 0;
[self stopPlayback];
}
- (NSUInteger)getLoopCount
{
return loopCount;
}
- (void)resetLoopCounter
{
loopCount = 0;
}
- (double)getRepeatNumber:(double)elapsedTime
{
// Use a more robust time-based method, rather than a loop-based method. This allows for jumping around in playback, while still having around the desired number of repeats in playback time.
return (elapsedTime * FRAMERATE - _loopStart) / (_loopEnd - _loopStart);
}
/*!
* Gets the number of active channels in the audio controller.
* @return The number of active channels in the audio controller.
*/
- (NSInteger)numChannels
{
return [[_audioController channels] count];
}
- (void)initAudioPlayer:(NSURL *)newURL :(NSError *)error
{
AEAudioFileLoaderOperation *operation = [[AEAudioFileLoaderOperation alloc] initWithFileURL:newURL
targetAudioDescription:_audioController.audioDescription];
[operation start];
if (operation.error)
{
error = operation.error;
}
else
{
/// Audio data to be loaded into the buffer.
AudioData *newData = malloc(sizeof(AudioData));
newData->numFrames = operation.lengthInFrames;
newData->playingList = operation.bufferList;
newData->loading = false;
newData->currentFrame = 0;
bufferAudioData = newData;
if (!_blockChannel)
{
_blockChannel =
[AEBlockChannel channelWithBlock:^(const AudioTimeStamp *time, UInt32 frames, AudioBufferList *audio)
{
AudioData *oldData = self->audioData;
self->audioData = self->bufferAudioData;
if (oldData != self->audioData)
{
self->freeData = oldData;
}
for (int i = 0; i < frames; i++)
{
for (int j = 0; j < 2; j++)
{
float currentVolume = self->_volume * self->_globalVolume;
if (currentVolume > 1)
{
currentVolume = 1;
}
((SInt16 *)audio->mBuffers[j].mData)[i] = ((SInt16 *)self->audioData->playingList->mBuffers[j].mData)[self->audioData->currentFrame] * currentVolume;
}
self->audioData->currentFrame++;
if (self->audioData->currentFrame >= self->audioData->numFrames)
{
self->audioData->currentFrame = 0;
self->loopCount++;
}
else if (!self->audioData->loading && self->audioData->currentFrame >= self->_loopEnd)
{
self->audioData->currentFrame = self->_loopStart;
self->loopCount++;
}
}
}];
}
}
}
- (AudioData *)getAudioData
{
return audioData;
}
- (NSMutableArray *)findLoopTime
{
/// Acceptable start points.
NSMutableArray *foundPoints = [[NSMutableArray alloc] init];
if (_loopEnd > audioData->numFrames - NUMMATCHINGFRAMES)
{
return foundPoints;
}
/// The range of the search in frames.
UInt32 searchRangeFrames = SEARCHRANGE * FRAMERATE;
if (audioData->numFrames < searchRangeFrames << 1 || _loopStart >= _loopEnd )
{
return foundPoints;
}
/// The end frames that must match with the start frames to be accepted.
SInt16 endFrames[NUMMATCHINGFRAMES * 2];
/// For loop iterator.
UInt32 i, j;
/// Counter for filling arrays.
UInt32 arrayCounter = 0;
for (i = _loopEnd; i < _loopEnd + NUMMATCHINGFRAMES; i++)
{
for (j = 0; j < 2; j++)
{
endFrames[arrayCounter++] = ((SInt16 *)audioData->playingList->mBuffers[j].mData)[i];
}
}
/// Whether an acceptable start point was found.
bool found;
/// The start point being examined.
UInt32 foundPoint = -1;
for (UInt32 k = 0; k < searchRangeFrames; k++)
{
for (SInt32 n = -1; n < 2; n += 2)
{
arrayCounter = 0;
foundPoint = _loopStart + k * n;
if (foundPoint >= audioData->numFrames)
{
continue;
}
found = true;
for (i = foundPoint; i < foundPoint + NUMMATCHINGFRAMES; i++)
{
for (j = 0; j < 2; j++)
{
/// The current sample from the loop start being compared.
SInt16 startSample = ((SInt16 *)audioData->playingList->mBuffers[j].mData)[i];
/// The current sample from the loop end being compared.
SInt16 endSample = endFrames[arrayCounter++];
if (abs(endSample - startSample) > SEARCHTOLERANCE)
{
found = false;
break;
}
}
if (!found)
{
break;
}
}
if (found)
{
break;
}
}
if (found)
{
/// The found start point to add to the array.
NSNumber *number = [NSNumber numberWithDouble:foundPoint / (NSTimeInterval)FRAMERATE];
[foundPoints addObject:number];
}
}
return foundPoints;
}
+ (UInt32)timeToFrame:(NSTimeInterval)time
{
return (UInt32)lround(time * FRAMERATE);
}
+ (NSTimeInterval)frameToTime:(UInt32)frame
{
return frame / (NSTimeInterval)FRAMERATE;
}
@end