c – Superpowered：实时音高变换,时间按钮不工作

我使用Superpowered用于各种实时FX,它们都非常直接.然而,音高变换是另一个故事,我认为实际上是因为它基于时间拉伸算法,当然必须处理时间变化的输出,这比应用像EQ或混响这样的FX要复杂得多.但是我只对改变麦克风输入的音高感兴趣.

我看了the only example I could find on GitHub,我稍微调整了它以适应我的工作：

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;
}

我删除了大部分我认为不必要的代码.例如,有一个while循环似乎处理时间拉伸场景,我只输出与输入相同的时间.

一些观察：

>如果我没有清除outputBuffers,那么我的内存使用量就会达到顶峰
>如果我使用self-> outputBuffers-> rewindSlice();应用程序变得沉默,可能意味着缓冲区被沉默覆盖
>如果我不使用self-> outputBuffers-> rewindSlice();我可以听到自己的声音回来,但timeStretchedAudio总是0,除了第一次

解决方法:

我终于搞定了：

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;
}

我不确定改变费率是否也有效,但我不关心这个应用程序.因人而异.

标签：c,superpowered
来源： https://codeday.me/bug/20190929/1831689.html