超级动力：时间延长器不起作用的实时音调转换 [英] Superpowered: real time pitch shift with timestretcher not working

问题描述

我将Superpowered用于各种实时FX，它们都非常简单。但是，音调转换完全是另外一回事了，我认为实际上是因为它基于时间拉伸算法，所以当然必须处理随时间变化的输出，这比应用诸如EQ或混响的FX复杂得多。但是我只对更改麦克风输入的音高感兴趣。

I am using Superpowered for various real-time FX and they all work very straightforward. However the pitch shifting is a whole other story, I think in fact because it's based on the time-stretching algorithm that of course has to deal with output that changes in time which is a lot more complex than applying FX like EQ or reverb. However I'm only interested in change the pitch of my mic input.

我看着我可以在GitHub上找到的唯一示例，我对其进行了一些调整以适应我的工作：

I looked at the only example I could find on GitHub and I slightly adapted it to fit my work:

static bool audioProcessing(void *clientdata,
                            float **buffers,
                            unsigned int inputChannels,
                            unsigned int outputChannels,
                            unsigned int numberOfSamples,
                            unsigned int samplerate,
                            uint64_t hostTime) {
    __unsafe_unretained Superpowered *self = (__bridge Superpowered *)clientdata;

    SuperpoweredAudiobufferlistElement inputBuffer;

    inputBuffer.startSample = 0;
    inputBuffer.samplesUsed = 0;
    inputBuffer.endSample = self->timeStretcher->numberOfInputSamplesNeeded;
    inputBuffer.buffers[0] = SuperpoweredAudiobufferPool::getBuffer(self->timeStretcher->numberOfInputSamplesNeeded * 8 + 64);
    inputBuffer.buffers[1] = inputBuffer.buffers[2] = inputBuffer.buffers[3] = NULL;

    self->outputBuffers->clear();
    self->timeStretcher->process(&inputBuffer, self->outputBuffers);
    int samples = self->timeStretcher->numberOfInputSamplesNeeded;
    float *timeStretchedAudio = (float *)self->outputBuffers->nextSliceItem(&samples);
    if (timeStretchedAudio != 0) {
        SuperpoweredDeInterleave(timeStretchedAudio, buffers[0], buffers[1], numberOfSamples);
    }

    //self->outputBuffers->rewindSlice();

    return true;
}

我删除了我认为不必要的大部分代码。例如，有一个while循环似乎处理时间延展的情况，我只是在输入时输出相同的时间。

I have removed most of the code that I thought wasn't necessary. For example there was a while loop that seemed to deal with time-stretch scenarios, I'm just outputting the same time as I input.

一些观察结果：

• 如果我不<< c $ c>清除 outputBuffers 我的内存使用量达到顶峰


• 如果我使用 self-> outputBuffers-> rewindSlice（）; 应用程序变得安静，这可能意味着缓冲区将被静音覆盖


• 如果我不使用 self-> outputBuffers-> rewindSlice（）; 我可以听到自己的声音回来，但是 timeStretchedAudio 总是 0 ，除了第一次

• If I don't clear the outputBuffers my memory usage goes through the roof
• If I use self->outputBuffers->rewindSlice(); the app becomes silent, probably meaning the buffers are getting overwritten with silence
• If I do not use self->outputBuffers->rewindSlice(); I can hear my own voice coming back, but timeStretchedAudio is always 0 except the very first time

推荐答案

我终于成功了：

static bool audioProcessing(void *clientdata,
                                float **buffers,
                                unsigned int inputChannels,
                                unsigned int outputChannels,
                                unsigned int numberOfSamples,
                                unsigned int samplerate,
                                uint64_t hostTime) {
    __unsafe_unretained Superpowered *self = (__bridge Superpowered *)clientdata;

    //timeStretching->setRateAndPitchShift(realTimeRate, realTimePitch);
    SuperpoweredAudiobufferlistElement inputBuffer;
    inputBuffer.startSample = 0;
    inputBuffer.samplesUsed = 0;
    inputBuffer.endSample = numberOfSamples;
    inputBuffer.buffers[0] = SuperpoweredAudiobufferPool::getBuffer((unsigned int) (numberOfSamples * 8 + 64));
    inputBuffer.buffers[1] = inputBuffer.buffers[2] = inputBuffer.buffers[3] = NULL;

    // Converting the 16-bit integer samples to 32-bit floating point.
    SuperpoweredInterleave(buffers[0], buffers[1], (float *)inputBuffer.buffers[0], numberOfSamples);
    //SuperpoweredShortIntToFloat(audioInputOutput, (float *)inputBuffer.buffers[0], (unsigned int) numberOfSamples);

    self->timeStretcher->process(&inputBuffer, self->outputBuffers);

    // Do we have some output?
    if (self->outputBuffers->makeSlice(0, self->outputBuffers->sampleLength)) {
        while (true) { // Iterate on every output slice.
            // Get pointer to the output samples.
            int numSamples = 0;
            float *timeStretchedAudio = (float *)self->outputBuffers->nextSliceItem(&numSamples);
            if (!timeStretchedAudio || *timeStretchedAudio == 0) {
                break;
            }

            // Convert the time stretched PCM samples from 32-bit floating point to 16-bit integer.
            //SuperpoweredFloatToShortInt(timeStretchedAudio, audioInputOutput,
            //                            (unsigned int) numSamples);
            SuperpoweredDeInterleave(timeStretchedAudio, buffers[0], buffers[1], numSamples);
            self->recorder->process(timeStretchedAudio, numSamples);

            // Write the audio to disk.
            //fwrite(audioInputOutput, 1, numSamples * 4, fd);
        }
        // Clear the output buffer list.
        self->outputBuffers->clear();
        // If we have enough samples in the fifo output buffer, pass them to the audio output.
        //SuperpoweredFloatToShortInt((float *)inputBuffer.buffers[0], audioInputOutput, (unsigned int) numberOfSamples);
    }

    return true;
}

我不确定是否可以更改汇率，但我不知道照顾这个应用程序。 YMMV。

I am not sure if changing the rate also works, but I don't care for this application. YMMV.

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