Method pull_graph

src/core/AudioDevice.cpp:18–82

using namespace lab;

void lab::pull_graph(AudioContext * ctx, AudioNodeInput * required_inlet, AudioBus * src, AudioBus * dst, int frames,
                     const SamplingInfo & info, AudioHardwareInput * optional_hardware_input)
{
    // The audio system might still be invoking callbacks during shutdown, so bail out if so.
    if (!ctx) 
        return;

    // bail if shutting down.
    auto ac = ctx->audioContextInterface().lock();
    if (!ac)
        return;

    ASSERT(required_inlet);

    ContextRenderLock renderLock(ctx, "lab::pull_graph");
    if (!renderLock.context()) return;  // return if couldn't acquire lock

    if (!ctx->isInitialized())
    {
        if (dst)
            dst->zero();
        return;
    }

    // Denormals can slow down audio processing.
    // Use an RAII object to protect all AudioNodes processed within this scope.

    /// @TODO under what circumstance do they arise?
    /// If they come from input data such as loaded WAV files, they should be corrected
    /// at source. If they can result from signal processing; again, where? The
    /// signal processing should not produce denormalized values.

    DenormalDisabler denormalDisabler;

    // Let the context take care of any business at the start of each render quantum.
    ctx->handlePreRenderTasks(renderLock);

    // Prepare the local audio input provider for this render quantum.
    if (optional_hardware_input && src)
    {
        optional_hardware_input->set(src);
    }

    // process the graph by pulling the inputs, which will recurse the entire processing graph.
    AudioBus * renderedBus = required_inlet->pull(renderLock, dst, frames);

    if (dst) {
        if (!renderedBus)
        {
            dst->zero();
        }
        else if (renderedBus != dst)
        {
            // in-place processing was not possible - so copy
            dst->copyFrom(*renderedBus);
        }
    }