在播放音频iOS时绘制波形？

Question

我要画一个波形而播放音频 ??

我在下面的链接 还检查与EZAudio和audiograph检查它并不能帮助我

Drawing waveform of audio on iOS without using AVAudioPlayer

是否有类似的方式任何教程或样本项目。 [绘制波形与AVAssetReader]的

Answer 1

- (void)startForFilePath:(NSString *)filePath 
{ 
    [self setNeedsDisplay]; 
    _playTime = 0.0f; 
    _audioFilePath = filePath; 

    NSURL *url = [NSURL fileURLWithPath:_audioFilePath]; 
    NSError *error = nil; 
    _player = [[AVAudioPlayer alloc] initWithContentsOfURL:url error:&error]; 
    if (_player == nil) 
    { 
     NSLog(@"player: %@ %ld %@", [error domain], (long)[error code], [[error userInfo] description]); 
     UIAlertView *alert = 
     [[UIAlertView alloc] initWithTitle: @"" 
            message: [error localizedDescription] 
            delegate: nil 
         cancelButtonTitle:@"OK" 
         otherButtonTitles:nil]; 
     [alert show]; 
     return; 
    } 
    _player.numberOfLoops = 0; 
    [_player prepareToPlay]; 
    _player.meteringEnabled = YES; 

    NSTimeInterval duration = _player.duration; 
    _waveUpdateFrequency = duration/(SOUND_METER_COUNT/2); 
    [_player play]; 

    _timer = [NSTimer scheduledTimerWithTimeInterval:_waveUpdateFrequency target:self selector:@selector(updateMeters) userInfo:nil repeats:YES]; 
} 

- (void)updateMeters 
{ 
    [_player updateMeters]; 
    if ((![_player isPlaying]) || (_playTime >= 60.0f)) { //60s 
     [self stop]; 
     return; 
    } 
    _playTime = _player.currentTime; 

    [self addSoundMeterItem:[_player averagePowerForChannel:0]]; 
} 

#pragma mark - Sound meter operations 
- (void)shiftSoundMeterLeft 
{ 
    for(int i = 0; i < SOUND_METER_COUNT - 1; i++) { 
     _soundMeters[i] = _soundMeters[i+1]; 
    } 
} 

- (void)shiftSoundMeterRight 
{ 
    for(int i = SOUND_METER_COUNT - 1; i >= 0 ; i--) { 
     _soundMeters[i] = _soundMeters[i-1]; 
    } 
} 

- (void)addSoundMeterItem:(int)lastValue 
{ 
    if (_isMeterRight) { 
     [self shiftSoundMeterRight]; 
     [self shiftSoundMeterRight]; 
     _soundMeters[0] = lastValue; 
     _soundMeters[1] = lastValue; 
    } 
    else { 
     [self shiftSoundMeterLeft]; 
     [self shiftSoundMeterLeft]; 
     _soundMeters[SOUND_METER_COUNT - 1] = lastValue; 
     _soundMeters[SOUND_METER_COUNT - 2] = lastValue; 
    } 

    [self setNeedsDisplay]; 
} 

#pragma mark - Drawing operations 
- (void)drawRect:(CGRect)rect 
{ 
    CGContextRef context = UIGraphicsGetCurrentContext(); 
    // Draw sound meter wave 
    [_meterWaveColor set]; 

    CGContextSetLineWidth(context, 1.0); 
    CGContextSetLineJoin(context, kCGLineJoinRound); 

    int baseLine = _frameRect.size.height/2; 
    int multiplier = 1; 
    int maxValueOfMeter = _frameRect.size.height/2 - 5; 
    for(CGFloat x = SOUND_METER_COUNT - 1; x >= 0; x--) 
    { 
     multiplier = ((int)x % 2) == 0 ? 1 : -1; 

     CGFloat y = baseLine + ((maxValueOfMeter * (MAX_LENGTH_OF_WAVE - abs(_soundMeters[(int)x])))/MAX_LENGTH_OF_WAVE) * multiplier; 

     if(x == SOUND_METER_COUNT - 1) { 
      CGContextMoveToPoint(context, x * (_frameRect.size.width/SOUND_METER_COUNT), y); 
      //CGContextAddLineToPoint(context, x * (_frameRect.size.width/SOUND_METER_COUNT) + 1, y); 
     } 
     else { 
      CGContextAddLineToPoint(context, x * (_frameRect.size.width/SOUND_METER_COUNT), y); 
      //CGContextAddLineToPoint(context, x * (_frameRect.size.width/SOUND_METER_COUNT) + 1, y); 
     } 
    } 

    CGContextStrokePath(context); 
}