常见的均衡器都是分为十段的，其他更多分段的操作起来不会很顺手。所以以十段均衡器为例。
IMG_6330.PNG
前几节中，MyAudioPlayer里面接入了一个AVAudioUnitEQ但没有设置相关属性，默认它是不工作的，因此需要做一些事。
先看看AVAudioUnitEQ里面有什么：
/*! @class AVAudioUnitEQ
@abstract An AVAudioUnitEffect that implements a Multi-Band Equalizer.
*/
@interface AVAudioUnitEQ : AVAudioUnitEffect
/*! @method initWithNumberOfBands:
@abstract Initialize the EQ with number of bands.
@param numberOfBands
The number of bands created by the EQ.
*/
- (instancetype)initWithNumberOfBands:(NSUInteger)numberOfBands;
/*! @property bands
@abstract Array of AVAudioUnitEQFilterParameters objects.
@discussion
The number of elements in the array is equal to the number of bands.
*/
@property (nonatomic, readonly) NSArray<AVAudioUnitEQFilterParameters *> *bands;
/*! @property globalGain
@abstract Overall gain adjustment applied to the signal.
@discussion
Range: -96 -> 24
Default: 0
Unit: dB
*/
@property (nonatomic) float globalGain;
@end
假设我们要分10段，直接用- (instancetype)initWithNumberOfBands:(NSUInteger)numberOfBands即可。然后还有一个AVAudioUnitEQFilterParameters数组对应了每一个分段。
/*! @class AVAudioUnitEQFilterParameters
@abstract Filter parameters used by AVAudioUnitEQ.
@discussion
A standalone instance of AVAudioUnitEQFilterParameters cannot be created. Only an instance
vended out by a source object (e.g. AVAudioUnitEQ) can be used.
*/
@interface AVAudioUnitEQFilterParameters : NSObject
- (instancetype)init NS_UNAVAILABLE;
/*! @property filterType
@abstract AVAudioUnitEQFilterType
@discussion
Default: AVAudioUnitEQFilterTypeParametric
*/
@property (nonatomic) AVAudioUnitEQFilterType filterType;
/*! @property frequency
@abstract Frequency in Hertz.
@discussion
Range: 20 -> (SampleRate/2)
Unit: Hertz
*/
@property (nonatomic) float frequency;
/*! @property bandwidth
@abstract Bandwidth in octaves.
@discussion
Range: 0.05 -> 5.0
Unit: Octaves
*/
@property (nonatomic) float bandwidth;
/*! @property gain
@abstract Gain in dB.
@discussion
Range: -96 -> 24
Default: 0
Unit: dB
*/
@property (nonatomic) float gain;
/*! @property bypass
@abstract bypass state of band.
@discussion
Default: YES
*/
@property (nonatomic) BOOL bypass;
@end
这些AVAudioUnitEQFilterParameters对象主要要用的属性有frequency、gain、bypass。
其中bypass默认YES的，也就是让信号直接通过而不处理，因此需要设为NO才能呈现效果。
然后遍历每一个frequency发现依次是40、57、83、120、174、251、264、526、5414、10000，和主流的32、64、125、250、500、1k、2k、4k、8k、16k不一致，也要改。
self.audioEQ = [[AVAudioUnitEQ alloc] initWithNumberOfBands:10];
NSArray *bands = self.audioEQ.bands;
NSInteger bandsCount = bands.count;
NSInteger maxFre = 16000;
// api默认的10分段是40、57、83、120、174、251、264、526、5414、10000，应该要改掉
// 假设是10段，那么市面上的频率分段为32、64、125、250、500、1k、2k、4k、8k、16k
for (NSInteger i = bandsCount - 1; i >= 0; i --) {
AVAudioUnitEQFilterParameters *ban = [bands objectAtIndex:i];
ban.bypass = NO;
ban.frequency = maxFre;
maxFre /= 2;
}
我认为均衡器数值变化用通知接收比较好，在MyAudioPlayer中添加一个通知处理：
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(eqDidChangedNotification:) name:kEQChangedNotificationName object:nil];
- (void)eqDidChangedNotification:(NSNotification *)notification {
NSArray *bands = [self.audioEQ.bands sortedArrayUsingComparator:^NSComparisonResult(AVAudioUnitEQFilterParameters *obj1, AVAudioUnitEQFilterParameters *obj2) {
if (obj1.frequency > obj2.frequency) {
return NSOrderedDescending;
}
return NSOrderedAscending;
}]; // 这里根据频率排序，避免设置错误。
NSInteger bandsCount = bands.count;
for (NSInteger i = 0; i < bandsCount; i ++) {
AVAudioUnitEQFilterParameters *ban = [bands objectAtIndex:i];
// NSLog(@"%f", ban.frequency);
CGFloat gainValue = [[[NSUserDefaults standardUserDefaults] valueForKey:[NSString stringWithFormat:@"%@%d", kEQBandKeyPrefix, (int)i]] floatValue];
// 这里我用UserDefualts存取各频段的增益值，key为kEQBandKeyPrefix + i, （读取方式很随意，取决于你怎么设置）
ban.bypass = gainValue == 0;
ban.gain = gainValue;
}
}
那么MyAudioPlayer里的部分就完成了，然后就到UI了。
基本思路就是做10个slider，然后CGAffineTransformMakeRotation旋转90度，设置slider的最大最小值，滑动时改UserDefualts内的数据，最后发送通知。
屏幕快照 2019-01-16 10.17.02.png
#import "EqualizerView.h"
#define kMaxGain (12)
#define kMinGain (-12)
@interface EqualizerView ()
@property (weak, nonatomic) IBOutlet UIView *sliderContainer;
@property (weak, nonatomic) IBOutlet UILabel *maxValueLabel;
@property (weak, nonatomic) IBOutlet UILabel *minValueLabel;
@end
@implementation EqualizerView
+ (void)show {
[[self defaultEqualizer] show];
}
+ (instancetype)defaultEqualizer {
EqualizerView *eqView = [[[UINib nibWithNibName:@"EqualizerView" bundle:nil] instantiateWithOwner:nil options:nil] firstObject];
if (![eqView isKindOfClass:self.class]) {
return [[self alloc] init];
}
[eqView config];
return eqView;
}
- (void)config {
self.maxValueLabel.text = [NSString stringWithFormat:@"%ddb", kMaxGain];
self.minValueLabel.text = [NSString stringWithFormat:@"%ddb", kMinGain];
CGRect containerRect = self.sliderContainer.bounds;
NSInteger count = kEQBandCount;
CGSize sliderSize = CGSizeMake(containerRect.size.height, containerRect.size.width / count);
CGFloat halfWidth = sliderSize.height / 2;
CGFloat centerY = containerRect.size.height / 2;
for (NSInteger i = 0; i < count; i ++) {
UISlider *slider = [[UISlider alloc] initWithFrame:CGRectMake(0, 0, sliderSize.width, sliderSize.height)];
slider.center = CGPointMake(halfWidth + i * sliderSize.height, centerY);
slider.transform = CGAffineTransformMakeRotation(-M_PI_2);
[self.sliderContainer addSubview:slider];
slider.tag = i;
[slider addTarget:self action:@selector(sliderValueChanged:) forControlEvents:UIControlEventValueChanged];
// sliders appearance
slider.continuous = NO;
slider.minimumTrackTintColor = [UIColor redColor];
slider.minimumValue = kMinGain;
slider.maximumValue = kMaxGain;
slider.value = [[[NSUserDefaults standardUserDefaults] valueForKey:[NSString stringWithFormat:@"%@%d", kEQBandKeyPrefix, (int)i]] floatValue] ;
}
}
- (void)sliderValueChanged:(UISlider *)slider {
long tag = slider.tag;
[[NSUserDefaults standardUserDefaults] setValue:@(slider.value) forKey:[NSString stringWithFormat:@"%@%ld", kEQBandKeyPrefix, tag]];
[self sendEQChangedNotification];
}
- (void)show {
[UIApplication.sharedApplication.keyWindow addSubview:self];
self.alpha = 0;
self.frame = self.superview.bounds;
[UIView animateWithDuration:0.25 animations:^{
self.alpha = 1;
}];
}
- (IBAction)close:(id)sender {
[UIView animateWithDuration:0.25 animations:^{
self.alpha = 0;
} completion:^(BOOL finished) {
[self removeFromSuperview];
}];
}
- (IBAction)resetAll:(id)sender {
NSArray *sliders = self.sliderContainer.subviews;
for (UISlider *slider in sliders) {
if ([slider isKindOfClass:[UISlider class]]) {
long tag = slider.tag;
slider.value = 0;
[[NSUserDefaults standardUserDefaults] setValue:@(slider.value) forKey:[NSString stringWithFormat:@"%@%ld", kEQBandKeyPrefix, tag]];
}
}
[self sendEQChangedNotification];
}
- (void)sendEQChangedNotification {
[[NSNotificationCenter defaultCenter] postNotificationName:kEQChangedNotificationName object:nil];
}
@end
外部找个入口调用[EqualizerView show];即可。
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