最近在項(xiàng)目中有個(gè)需求，公司有一個(gè)設(shè)備兔辅，能夠獲取音頻腊敲，音頻傳輸過(guò)來(lái)，解碼后就播放了维苔，需求就是播放時(shí)碰辅，根據(jù)聲音進(jìn)行添加波形動(dòng)畫，網(wǎng)上有一些資源介时，大多都是用AVAudioRecorder的averagePowerForChannel方法没宾，獲取麥上獲取到的音量，然后動(dòng)畫顯示沸柔，如果是一個(gè)PCM碼流的話循衰，需要自己獲取對(duì)應(yīng)的音量信息，而后顯示在動(dòng)畫上了褐澎，后面我找了一些資料会钝，把PCM的數(shù)據(jù)解析出音量信息，然后再顯示工三，效果還可以迁酸，發(fā)出來(lái)參考一下。

先來(lái)點(diǎn)基礎(chǔ)的知識(shí)俭正，首先是采樣頻率奸鬓，指每秒鐘取得聲音樣本的次數(shù)，采樣頻率越高段审，包含的聲音信息自然就越多全蝶，聲音也就越好闹蒜，頻率越高，保存需要的空間也會(huì)高抑淫，所以不一定越高越好绷落，看實(shí)際需求。
采樣位寬始苇，即采樣值砌烁，一般分為8位和16位，可以表示的范圍分別是2^8和216的區(qū)間催式，區(qū)間越大函喉，分辨率也就越大，發(fā)出聲音大能力也就越強(qiáng)荣月，同樣的管呵，位寬越大，需要的空間也就越大哺窄。
聲道數(shù)捐下，分為單聲道和雙聲道，雙聲道即立體聲萌业。

另外一些信息坷襟，需要一些理解能力，鏈接中有詳細(xì)的過(guò)程
dB = 20×log(data^2),data是從PCM中獲取到的對(duì)應(yīng)位寬的數(shù)據(jù)生年，例如婴程，如果是8位就是一個(gè)字節(jié)，如果是16位就是2個(gè)字節(jié)
Y = A×sin(2×M_PI×X+Phase),X是橫坐標(biāo)抱婉，phase是相位
Y = (cos(M_PI+2×M_PI×X)+1)/2,X是0～1之間的一個(gè)值

再來(lái)分析一下我需求中的一些信息档叔，我的解碼后獲取到的PCM碼流是位寬為16位，采樣頻率為16KHz的單聲道數(shù)據(jù)授段，每秒鐘的碼流解碼后的PCM數(shù)據(jù)會(huì)被分為5個(gè)包蹲蒲，通過(guò)計(jì)算番甩，每個(gè)包的大小是(16×16000×1/8)/5 ＝ 6400(字節(jié))侵贵，在程序中，我們使用的是CADisplayLink的定時(shí)刷新功能缘薛，以和屏幕一樣的刷新頻率刷新窍育，也就是60Hz，也就是說(shuō)宴胧，我們應(yīng)該保持讓屏幕每隔1/60秒就更新到一個(gè)新數(shù)據(jù)漱抓，所以，解碼后恕齐，每秒的數(shù)據(jù)應(yīng)該被分割成60個(gè)音量值乞娄，也就是說(shuō)，五個(gè)包，每個(gè)包有6400個(gè)字節(jié)仪或，一個(gè)包可以獲取到12個(gè)音量值确镊，大概每1600/3個(gè)字節(jié)就得取到一個(gè)音量平均值，這樣就可以簡(jiǎn)單的實(shí)現(xiàn)在屏幕上顯示一段音頻波形動(dòng)畫了范删，不過(guò)蕾域，要注意的是，雖然每隔1/60秒刷新一個(gè)新的數(shù)據(jù)可以讓你的波形得到接近表現(xiàn)真實(shí)的音頻到旦，但是會(huì)導(dǎo)致動(dòng)畫的效果會(huì)發(fā)生類似抖動(dòng)的效果旨巷，因?yàn)椋噜彽拿總€(gè)波形直接添忘，音量差異可能比較大采呐，從一個(gè)波形到另一個(gè)波形的跨度大的話，在切換過(guò)去的時(shí)候就會(huì)出現(xiàn)跳過(guò)去的感覺搁骑，也就是抖動(dòng)懈万，解決這種抖動(dòng)現(xiàn)象需要用到插值，先把從PCM數(shù)據(jù)取音量的次數(shù)降下來(lái)靶病，原來(lái)每個(gè)小包取6400個(gè)字節(jié)取12個(gè)音量值会通，你改為取4次壳嚎，也就是的烁，每6400/4=1600字節(jié)就取一個(gè)音量值，然后兩個(gè)音量值之間再通過(guò)插值的方法秒旋，取2個(gè)值煤辨，我這邊直接簡(jiǎn)單的用一次線性插值取值裳涛，這樣可以使抖動(dòng)不那么明顯，甚至看不出來(lái)众辨，如果還有明顯的抖動(dòng)端三，可以以此類推，再減少取值數(shù)量鹃彻，增加插值數(shù)量郊闯。

/*音頻解碼成功后，在主線程中調(diào)用updateVolume方法蛛株，處理PCM數(shù)據(jù)獲取音頻波形需要的信息*/
-(void)OnDecodeAudio:(unsigned char*)data Length:(int)length
{
    if (![_device SupportFunction:FUNCTION_VIDEO]) {
        _isFramePreparedOK = YES;
    }
    if (_progressView.isProgressing) {
        return;
    }
    //輸出
    if (_audioPlay) {
        //
        if (_isSpeaking || _isSilence) {
            _audioPlay->Silence(true);
        }
        else{
            _audioPlay->Silence(false);
        }
        //
        if (![_device SupportFunction:FUNCTION_VIDEO]) {
            /*data為PCM數(shù)據(jù)团赁，長(zhǎng)度為length個(gè)字節(jié)，保存到NSData中方便處理*/
            _audioData = [NSData dataWithBytes:data length:length];
            NSData* copyData = [_audioData copy];
            [self performSelectorOnMainThread:@selector(updateVolume:) withObject:copyData waitUntilDone:NO];
        }
        //NSLog(@"OnDecodeAudio length(%d)",length);
        if (!_audioPlay->Show((char*)data, length)) {
            HHAudioPresent_Destroy(_audioPlay);
            _audioPlay = NULL;
        }
    }
}
-(void)updateVolume:(NSData*)volumeData
{
    if (![_device SupportFunction:FUNCTION_VIDEO]) {
        /*獲取PCM中的振幅系數(shù)信息*/
        NSArray* ampValueArray = [self pcmToAverageAmplitude:volumeData];
        /*添加到音頻波形隊(duì)列中谨履，且在添加前欢摄，進(jìn)行插值*/
        for (NSInteger i = 0; i < ampValueArray.count; i++) {
            [_voiceWaveView changeVolume:[ampValueArray[i] floatValue]];
        }
    }
}
/*  把獲取到的PCM數(shù)據(jù)進(jìn)行處理，得到音頻振幅系數(shù)信息
 *  @param  volumeData  PCM數(shù)據(jù)
 */
-(NSArray*)pcmToAverageAmplitude:(NSData*)volumeData
{
    NSMutableArray* array = [NSMutableArray array];
    short bufferBytes[volumeData.length/2];
    memcpy(bufferBytes, volumeData.bytes, volumeData.length);
    NSInteger packets = 2;
    // 將 buffer 內(nèi)容取出笋粟，進(jìn)行平方和運(yùn)算
    for (int i = 0; i < packets; i++)
    {
        long long pcmSum = 0;
        NSUInteger size = volumeData.length/packets/2;
        for (int j = 0; j < size; j++) {
            pcmSum += bufferBytes[size*i+j]*bufferBytes[size*i+j];
        }
        double mean = pcmSum / size/2;
        double volume = 10*log10(mean);
        double maxVolume = 20*log10(pow(2, 16)-1);
        [array addObject:[NSNumber numberWithDouble:volume/maxVolume]];
    }
    return [array copy];
}

某一個(gè)音量值上怀挠，我們使用貝塞爾曲線來(lái)畫波形析蝴，用CAShapeLayer的遮蓋，先在layer上加一條透明的貝塞爾曲線绿淋，這個(gè)曲線是一條正弦波嫌变，頻率固定，再加一個(gè)相位躬它，然后振幅的話腾啥，可以用整個(gè)view的高的一半作為最大振幅，把PCM的音量大小冯吓，作為最大振幅的百分比倘待，這樣，這樣组贺，音量變高的時(shí)候凸舵，出來(lái)的波峰波谷就會(huì)變大，反之變小失尖，就能夠畫出想要的效果啊奄，最大振幅的百分比是通過(guò)以當(dāng)前音量做分子，以系統(tǒng)可以表示的最大音量為分母得到的掀潮，比如菇夸，如果是16位位寬的PCM數(shù)據(jù)的話，最大的音量應(yīng)該是20×log(1/(2^16-1)=-96.32dB仪吧，如果是普通室內(nèi)的聲音庄新，大概在－35dB左右，那振幅百分比就是 36.4% 薯鼠，表示在圖形上择诈，就是會(huì)出現(xiàn)一個(gè)波峰占了整個(gè)View高度36.4%的波形

MCVoiceWaveView.h

//
//  MCVoiceWaveView.h
//  MCVoiceWave
//
//  Created by 朱進(jìn)林 on 10/8/16.
//  Copyright ? 2016 Martin Choo. All rights reserved.
//

#import <UIKit/UIKit.h>

#pragma mark - HHVolumeQueue
@interface MCVolumeQueue : NSObject

-(void)pushVolume:(CGFloat)volume;
-(void)pushVolumeWithArray:(NSArray*)array;
-(CGFloat)popVolume;
-(void)cleanQueue;
@end

#pragma mark - HHVoiceWaveView
@interface MCVoiceWaveView : UIView
/**
 *  添加并初始化波紋視圖
 *  parentView:父視圖
 */
-(void)showInParentView:(UIView*)parentView;
/**
 *  開始聲波動(dòng)畫
 */
-(void)startVoiceWave;
/**
 *  改變音量來(lái)改變聲波幅度
 *  volume:音量大小
 */
-(void)changeVolume:(CGFloat)volume;
/**
 *  停止聲波動(dòng)畫
 */
-(void)stopVoiceWave;
/**
 *  移掉聲波
 */
-(void)removeFromParent;
@end

MCVoiceWaveView.m

//
//  MCVoiceWaveView.m
//  MCVoiceWave
//
//  Created by 朱進(jìn)林 on 10/8/16.
//  Copyright ? 2016 Martin Choo. All rights reserved.
//

#import "MCVoiceWaveView.h"

#define voiceWaveDisappearDuration 0.25
#define minVolume 0.05
static NSRunLoop* _voiceWaveRunLoop;

#pragma mark - MCVolumeQueue
@interface MCVolumeQueue()

@property (nonatomic, strong) NSMutableArray* volumeArray;
@end
@implementation MCVolumeQueue

-(instancetype)init
{
    self = [super init];
    if (self) {
        self.volumeArray = [NSMutableArray array];
    }
    return self;
}
-(void)pushVolume:(CGFloat)volume
{
    if (volume >= minVolume) {
        [_volumeArray addObject:[NSNumber numberWithFloat:volume]];
    }
}
-(void)pushVolumeWithArray:(NSArray *)array
{
    if (array.count > 0) {
        for (NSInteger i = 0; i < array.count; i++) {
            CGFloat volume = [array[i] floatValue];
            [self pushVolume:volume];
        }
    }
}
-(CGFloat)popVolume
{
    CGFloat volume = -10;
    if (_volumeArray.count > 0) {
        volume = [[_volumeArray firstObject] floatValue];
        [_volumeArray removeObjectAtIndex:0];
    }
    return volume;
}
-(void)cleanQueue
{
    if (_volumeArray) {
        [_volumeArray removeAllObjects];
    }
}
@end

#pragma mark - MCVoiceWaveView
@interface MCVoiceWaveView(){
    CGFloat _idleAmplitude;//最小振幅
    CGFloat _amplitude;//振幅系數(shù)，表示音量在屏幕上高度的比例
    CGFloat _density;//X軸粒度出皇，粒度越小羞芍，線條越順
    CGFloat _waveHeight;//波形圖所在view的高
    CGFloat _waveWidth;//波形圖所在view的寬
    CGFloat _waveMid;//波形圖所在view的中點(diǎn)
    CGFloat _maxAmplitude;//最大振幅
    //可以多畫幾根線，使聲波波形看起來(lái)更復(fù)雜真實(shí)
    CGFloat _phase;//初始相位位移
    CGFloat _phaseShift;//_phase累進(jìn)的相位位移量郊艘，造成向前推移的感覺
    CGFloat _frequencyFirst;//firstLine在view上的頻率
    CGFloat _frequencySecond;//secondLine在view上的頻率
    //
    CGFloat _currentVolume;//音量相關(guān)
    CGFloat _lastVolume;
    CGFloat _middleVolume;
    //
    CGFloat _maxWidth;//波紋顯示最大寬度
    CGFloat _beginX;//波紋開始坐標(biāo)
    CGFloat _stopAnimationRatio;//衰減系數(shù),停止后避免音量過(guò)大荷科，波紋振幅大，乘以衰減系數(shù)
    BOOL _isStopAnimating;//正在進(jìn)行消失動(dòng)畫
    //
    UIBezierPath* _firstLayerPath;
    UIBezierPath* _secondLayerPath;
}
@property (nonatomic, strong) CADisplayLink* displayLink;
@property (nonatomic, strong) CAShapeLayer* firstShapeLayer;
@property (nonatomic, strong) CAShapeLayer* secondShapeLayer;
@property (nonatomic, strong) CAShapeLayer* fillShapeLayer;
//
@property (nonatomic, strong) UIImageView* firstLine;
@property (nonatomic, strong) UIImageView* secondLine;
@property (nonatomic, strong) UIImageView* fillLayerImage;
//
@property (nonatomic, strong) MCVolumeQueue* volumeQueue;

@end
@implementation MCVoiceWaveView

-(void)setup
{
    _frequencyFirst = 2.0f;//2個(gè)周期
    _frequencySecond = 1.8f;//1.6個(gè)周期暇仲，更平緩步做，有點(diǎn)周期差，使圖像看起來(lái)更有錯(cuò)落感
    
    _amplitude = 1.0f;
    _idleAmplitude = 0.01f;
    
    _phase = 0.0f;
    _phaseShift = -0.22f;
    _density = 1.f;
    
    _waveHeight = CGRectGetHeight(self.bounds);
    _waveWidth  = CGRectGetWidth(self.bounds);
    _waveMid    = _waveWidth / 2.0f;
    _maxAmplitude = _waveHeight * 0.5;
    
    _maxWidth = _waveWidth + _density;
    _beginX = 0.0;
    
    _lastVolume = 0.0;
    _currentVolume = 0.0;
    _middleVolume = 0.01;
    _stopAnimationRatio = 1.0;
    
    [_volumeQueue cleanQueue];
}

-(instancetype)init
{
    self = [super init];
    if (self) {
        [self startVoiceWaveThread];
    }
    return self;
}

-(void)dealloc
{
    [_displayLink invalidate];
}

-(void)voiceWaveThreadEntryPoint:(id)__unused object
{
    @autoreleasepool {
        [[NSThread currentThread] setName:@"com.anxin-net.VoiceWave"];
        _voiceWaveRunLoop = [NSRunLoop currentRunLoop];
        [_voiceWaveRunLoop addPort:[NSMachPort port] forMode:NSDefaultRunLoopMode];
        [_voiceWaveRunLoop run];
    }
}

-(NSThread*)startVoiceWaveThread
{
    static NSThread* _voiceWaveThread = nil;
    static dispatch_once_t oncePredicate;
    dispatch_once(&oncePredicate, ^{
        _voiceWaveThread = [[NSThread alloc] initWithTarget:self selector:@selector(voiceWaveThreadEntryPoint:) object:nil];
        [_voiceWaveThread start];
    });
    return _voiceWaveThread;
}

-(void)showInParentView:(UIView *)parentView
{
    if (![self.superview isKindOfClass:[parentView class]] || !_isStopAnimating) {
        [parentView addSubview:self];
    }else {
        [self.layer removeAllAnimations];
        return;
    }
    //
    self.frame =CGRectMake(0, 0, parentView.bounds.size.width, parentView.bounds.size.height);
    [self setup];
    //
    [self addSubview:self.firstLine];
    self.firstLine.frame = self.bounds;
    CGFloat firstLineWidth = 5 / [UIScreen mainScreen].scale;
    self.firstShapeLayer = [self generateShaperLayerWithLineWidth:firstLineWidth];
    self.firstLine.layer.mask = self.firstShapeLayer;
    //
    [self addSubview:self.secondLine];
    self.secondLine.frame = self.bounds;
    CGFloat secondLineWidth = 4 / [UIScreen mainScreen].scale;
    self.secondShapeLayer = [self generateShaperLayerWithLineWidth:secondLineWidth];
    self.secondLine.layer.mask = self.secondShapeLayer;
    //
    [self addSubview:self.fillLayerImage];
    _fillLayerImage.frame = self.bounds;
    _fillLayerImage.layer.mask = self.fillShapeLayer;
    //
    [self updateMeters];
}

-(void)startVoiceWave
{
    if (_isStopAnimating) {
        return;
    }
    [self setup];
    if (_voiceWaveRunLoop) {
        [self.displayLink invalidate];
        self.displayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(invokeWaveCallback)];
        [self.displayLink addToRunLoop:_voiceWaveRunLoop forMode:NSRunLoopCommonModes];
    }else {
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.3*NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
            if (_voiceWaveRunLoop) {
                [self.displayLink invalidate];
                self.displayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(invokeWaveCallback)];
                [self.displayLink addToRunLoop:_voiceWaveRunLoop forMode:NSRunLoopCommonModes];
            }
        });
    }
}

-(void)stopVoiceWave
{
    if (_isStopAnimating) {
        return;
    }
    [self.layer removeAllAnimations];
    _isStopAnimating = YES;
}

-(void)changeVolume:(CGFloat)volume
{
    @synchronized (self) {
        _lastVolume = _currentVolume;
        _currentVolume = volume;
        //
        NSArray* volumeArray = [self generatePointsOfSize:6 withPowFactor:1 fromStartY:_lastVolume toEndY:_currentVolume];
        [self.volumeQueue pushVolumeWithArray:volumeArray];
    }
}

-(void)removeFromParent
{
    [_displayLink invalidate];
    [self removeFromSuperview];
}

-(void)invokeWaveCallback
{
    [self updateMeters];
}

-(void)updateMeters
{
    CGFloat volume = [self.volumeQueue popVolume];
    if (volume > 0) {
        _middleVolume = volume;
    }else {
        _middleVolume -= 0.01;
    }
    _phase += _phaseShift;
    _amplitude = fmax(_middleVolume, _idleAmplitude);
    if (_isStopAnimating) {
        _stopAnimationRatio -=0.05;
        _stopAnimationRatio = fmax(_stopAnimationRatio, 0.01);
        if (_stopAnimationRatio == 0.01) {
            [self animationStopped];
        }
    }
    _firstLayerPath = nil;
    _secondLayerPath = nil;
    _firstLayerPath = [self generateBezierPathWithFrequency:_frequencyFirst maxAmplitude:_maxAmplitude phase:_phase];
    _secondLayerPath = [self generateBezierPathWithFrequency:_frequencySecond maxAmplitude:_maxAmplitude * 0.8 phase:_phase+3];
    //
    NSDictionary* dic = @{@"firstPath":_firstLayerPath,@"secondPath":_secondLayerPath};
    [self performSelectorOnMainThread:@selector(updateShapeLayerPath:) withObject:dic waitUntilDone:NO];
}

-(void)updateShapeLayerPath:(NSDictionary*)dic
{
    UIBezierPath* firstPath = [dic objectForKey:@"firstPath"];
    _firstShapeLayer.path = firstPath.CGPath;
    UIBezierPath* secondPath = [dic objectForKey:@"secondPath"];
    _secondShapeLayer.path = secondPath.CGPath;
    if (firstPath && secondPath) {
        UIBezierPath* fillPath = [UIBezierPath bezierPathWithCGPath:firstPath.CGPath];
        [fillPath appendPath:secondPath];
        [fillPath closePath];
        _fillShapeLayer.path = fillPath.CGPath;
    }
}

-(void)animationStopped
{
    [self.displayLink invalidate];
    _isStopAnimating = NO;
    //
    self.layer.mask = nil;
    _lastVolume = 0.0;
    _currentVolume = 0.0;
    _middleVolume = 0.05;
    [_volumeQueue cleanQueue];
}

#pragma mark - generate
-(CAShapeLayer*)generateShaperLayerWithLineWidth:(CGFloat)lineWidth
{
    CAShapeLayer* waveLine = [CAShapeLayer layer];
    waveLine.lineCap = kCALineCapButt;
    waveLine.lineJoin = kCALineJoinRound;
    waveLine.strokeColor = [UIColor redColor].CGColor;
    waveLine.fillColor = [UIColor clearColor].CGColor;
    waveLine.lineWidth = lineWidth;
    waveLine.backgroundColor = [UIColor clearColor].CGColor;
    return  waveLine;
}
/** 根據(jù)頻率奈附，最大振幅，相位等信息煮剧，得到代表當(dāng)前音量的波形
 */
-(UIBezierPath*)generateBezierPathWithFrequency:(CGFloat)frequency maxAmplitude:(CGFloat)maxAmplitude phase:(CGFloat)phase
{
    UIBezierPath* waveLinePath = [UIBezierPath bezierPath];
    CGFloat normedAmplitude = fmin(_amplitude, 1.0);//振幅百分比斥滤，最高只能是1
    //按X軸粒度連接多個(gè)點(diǎn)将鸵，拼接在一起，形成類似曲線的波形
    for (CGFloat x = _beginX; x < _maxWidth; x += _density) {
        CGFloat scaling = (1+cosf(M_PI+(x/_maxWidth)*2*M_PI))/2;
        CGFloat y = scaling * _maxAmplitude * normedAmplitude * _stopAnimationRatio * sinf(2 * M_PI * (x / _waveWidth) * frequency + phase) + (_waveHeight * 0.5);
        if (_beginX == x) {
            [waveLinePath moveToPoint:CGPointMake(x, y)];
        }else {
            [waveLinePath addLineToPoint:CGPointMake(x, y)];
        }
    }
    return waveLinePath;
}
/**插值方法佑颇，在相鄰的兩個(gè)值中間顶掉，插入若干個(gè)值，使波形切換時(shí)過(guò)渡更平滑*/
-(NSArray*)generatePointsOfSize:(NSInteger)size withPowFactor:(CGFloat)factor fromStartY:(CGFloat)startY toEndY:(CGFloat)endY
{
    BOOL factorValid = factor < 2 && factor > 0 && factor != 0;
    BOOL startYValid = 0 <= startY && startY <= 1;
    BOOL endYValid = 0 <= endY && endY <= 1;
    if (!(factorValid && startYValid && endYValid)) {
        return nil;
    }
    //
    NSMutableArray* mArray = [NSMutableArray arrayWithCapacity:size];
    CGFloat startX,endX;
    startX = pow(startY, 1/factor);
    endX = pow(endY, 1/factor);
    //
    CGFloat pieceOfX = (endX - startX) / size;
    CGFloat x,y;
    [mArray addObject:[NSNumber numberWithFloat:startY]];
    for (int i = 1; i < size; ++i) {
        x = startX + pieceOfX * i;
        y = pow(x, factor);
        [mArray addObject:[NSNumber numberWithFloat:y]];
    }
    return [mArray copy];
}
#pragma mark - getter
-(UIImageView*)firstLine
{
    if (!_firstLine) {
        self.firstLine = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"pic_firstLine.png"]];
        _firstLine.layer.masksToBounds = YES;
    }
    return _firstLine;
}
-(UIImageView*)secondLine
{
    if (!_secondLine) {
        self.secondLine = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"pic_secondLine.png"]];
        _secondLine.layer.masksToBounds = YES;
        _secondLine.alpha = 0.6;
    }
    return _secondLine;
}
-(UIImageView*)fillLayerImage
{
    if (!_fillLayerImage) {
        self.fillLayerImage = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"pic_fill.png"]];
        _fillLayerImage.layer.masksToBounds = YES;
        _fillLayerImage.alpha = 0.2;
    }
    return _fillLayerImage;
}
-(CAShapeLayer*)fillShapeLayer
{
    if (!_fillShapeLayer) {
        self.fillShapeLayer = [CAShapeLayer layer];
        _fillShapeLayer.lineCap = kCALineCapButt;
        _fillShapeLayer.lineJoin = kCALineJoinRound;
        _fillShapeLayer.strokeColor = [UIColor clearColor].CGColor;
        _fillShapeLayer.fillColor = [UIColor redColor].CGColor;
        _fillShapeLayer.fillRule = @"even-odd";
        _fillShapeLayer.lineWidth = 2;
        _fillShapeLayer.backgroundColor = [UIColor clearColor].CGColor;
    }
    return _fillShapeLayer;
}
-(MCVolumeQueue*)volumeQueue
{
    if (!_volumeQueue) {
        self.volumeQueue = [[MCVolumeQueue alloc] init];
    }
    return _volumeQueue;
}
@end

以上部分代碼涉及公司機(jī)密挑胸，不方便把全部源碼貼出痒筒，我在Github上貼出的是通過(guò)捕捉麥克風(fēng)輸入的音頻的波形，如果有改進(jìn)建議或者疑問的話茬贵，可以聯(lián)系我簿透，感謝分享！
效果圖：

效果圖1.gif

這是用AVAudioRecord獲取麥克風(fēng)的音頻解藻，獲取PCM數(shù)據(jù)進(jìn)行處理后老充，得到的效果圖如下：

效果圖2.gif

參考資料鏈接

音量分貝計(jì)算：http://www.cnblogs.com/karlchen/archive/2007/04/10/707478.html
貝塞爾曲線：http://blog.csdn.net/likendsl/article/details/7852658
附上函數(shù)圖像繪制工具