播放音频iOS时绘制波形？

Question

我想在播放音频的同时绘制波形？？

我检查了以下链接 还检查了 EZAudio 和 audiograph 它对我没有帮助

Drawing waveform of audio on iOS without using AVAudioPlayer

是否有类似的教程或示例项目。

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);
}