在音频回调中随时间间隔更改变量

Question

所以我想在一段时间内更改 for 循环中的变量。在我的代码中，我的音频回调基本上是运行以下伪代码：

int start = 0, target = 100;
for (int i = 0; i < frames; i++) {
    [object makeSineWave];
    [object useNum:start];
    if (target > start) {
        // Increase start over the span of time frame
    }
}

我想要做的是在一个时间间隔内以对数标度将开始值增加到目标值（为简单起见，假设为 1 秒）。我如何在音频回调的 for 循环中跟踪时间？

编辑：猜猜我正在尝试进行滤波器扫描...我猜现在我想它会类似于正弦扫描？更多代码-

OSStatus RenderTone(void *inRefCon,
                AudioUnitRenderActionFlags *ioActionFlags,
                const AudioTimeStamp *inTimeStamp,
                UInt32 inBusNumber,
                UInt32 inNumberFrames,
                AudioBufferList *ioData) {
    // Get Audio Data
    AudioData *data = (__bridge AudioData *)inRefCon;
    static Float32 phs = 0, sub_phs = 0;
    Float32 freq = data->freq;
    // Calculate phases
    Float32 phs_incr = 2 * M_PI * freq / data->srate;
    Float32 sample;

    // Buffers
    Float32 *bufL = (Float32 *)ioData->mBuffers[0].mData;
    Float32 *bufR = (Float32 *)ioData->mBuffers[1].mData;

    // Start at 1 hz, target is 500 hz
    int start = 1, target = 500;

    // Generate Samples
    for (UInt32 i = 0; i < inNumberFrames; i++) {
        // Sine waveform
        sample = sinf(phs);
        sample = [data->filter processFilter:sample fc:start];

        // change start here using current time?
        // should not increase to target immediately, over span of 1 second

        bufL[i] = buf[R] = sample;

        // Increment phase
        phs += phs_incr;
        // Wrap phase
        phs = wrapPhase(phs);
    }
}

Answer 1

我似乎通过查看 CCRMA 的 STK 找到了如何做到这一点...我希望我早点找到的好资源！

https://ccrma.stanford.edu/software/stk/

在音频回调中随时间间隔更改变量

Change Variable over Time Interval in Audio Callback

time

objective-c

callback

core-audio