Question

我正在尝试使用AVAudioUnitSampler创建钢琴乐器。我不想为每个钢琴琴键提供一个wav文件，而是希望AVAudioUnitSampler插入两者之间的缺失值。例如，如果我为C3和D3提供一个wav文件，它应该能够使用其中一个生成C＃3（C3和D3之间的注释）。在文档中，它提到您可以在文件名中提供范围，但是我不确定这是如何工作的，因为文档没有涉及太多细节。这是加载音频文件的方法的说明：

将音频文件加载到新乐器中，并将每个音频文件放置在其自己的采样器区域中。会使用音频文件中包含的有关它们在乐器中放置的任何信息，例如，根键，键范围。

这是我的工作代码：

Sampler.h

#import <Foundation/Foundation.h>

@interface Sampler : NSObject

@property double volume;

@end

Sampler.m

#import "Sampler.h"


@interface Sampler()

@property AVAudioEngine *engine;
@property AVAudioMixerNode *mixer;
@property AVAudioUnitSampler *sampler;

@end

@implementation Sampler

-(instancetype) init {
    if (self = [super init]) {
        [self initVolume];
        [self loadSampler];
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(midiPlayed:) name:@"MidiPlayedNotificationKey" object:nil];
    }
    return self;
}

-(void) initVolume {
    _volume = 1.0; //CHANGE LATER
}

//loads the drum kit
-(void) loadSampler {
    // Instatiate audio engine
    _engine = [[AVAudioEngine alloc] init];
    _mixer = [_engine mainMixerNode];
    _sampler = [[AVAudioUnitSampler alloc] init];

    [self loadSamples];

    [self makeEngineConnections];
    [self startEngine];
}

-(void) loadSamples {
    NSString *instrument = @"PianoSamples";
    NSArray *urls = [[NSBundle mainBundle] URLsForResourcesWithExtension:@"wav" subdirectory:instrument];
    [_sampler loadAudioFilesAtURLs:urls error:nil];
}

-(void)makeEngineConnections {
    [_engine attachNode:_sampler];
    [_engine connect:_sampler to:_mixer format:[_sampler outputFormatForBus:0]];
}

-(void)startEngine {
    [_engine startAndReturnError:nil];
}

//plays the sound when a MIDI note is played
-(void) midiPlayed:(NSNotification*)notification {
    bool isKeyPlayed = [notification.userInfo[@"isKeyPlayed"] boolValue];

    if (isKeyPlayed) {
        int noteValue = [notification.userInfo[@"note"] intValue];
        [_sampler startNote:noteValue withVelocity:_volume*127 onChannel:0];
        NSLog(@"note value = %d", noteValue);
    }
}

@end

创建内插音符的采样器

0 个答案: