linux-wallpaperengine-kde/src/WallpaperEngine/Audio/Drivers/Recorders/CPulseAudioPlaybackRecorder.cpp

#include "CPulseAudioPlaybackRecorder.h"
#include "External/Android/fft.h"
#include "WallpaperEngine/Logging/CLog.h"
#include <cmath>
#include <cstring>
#include <glm/common.hpp>

namespace WallpaperEngine::Audio::Drivers::Recorders {
float movetowards (float current, float target, float maxDelta) {
    if (abs (target - current) <= maxDelta)
        return target;

    return current + glm::sign (target - current) * maxDelta;
}

void pa_stream_notify_cb (pa_stream* stream, void* /*userdata*/) {
    switch (pa_stream_get_state (stream)) {
        case PA_STREAM_FAILED: sLog.error ("Cannot open stream for capture. Audio processing is disabled"); break;
        case PA_STREAM_READY: sLog.debug ("Capture stream ready"); break;
    }
}

void pa_stream_read_cb (pa_stream* stream, const size_t /*nbytes*/, void* userdata) {
    auto* recorder = static_cast<CPulseAudioPlaybackRecorder*> (userdata);

    // Careful when to pa_stream_peek() and pa_stream_drop()!
    // c.f. https://www.freedesktop.org/software/pulseaudio/doxygen/stream_8h.html#ac2838c449cde56e169224d7fe3d00824
    const void* data = nullptr;
    size_t currentSize;
    if (pa_stream_peek (stream, &data, &currentSize) != 0) {
        sLog.error ("Failed to peek at stream data...");
        return;
    }

    if (data == nullptr && currentSize == 0) {
        // No data in the buffer, ignore.
        return;
    }

    if (data == nullptr && currentSize > 0) {
        // Hole in the buffer. We must drop it.
        if (pa_stream_drop (stream) != 0) {
            sLog.error ("Failed to drop a hole while capturing!");
            return;
        }
    } else if (currentSize > 0 && data) {
        size_t dataToCopy = std::min (currentSize, WAVE_BUFFER_SIZE - recorder->currentWritePointer);

        memcpy (&recorder->audio_buffer_tmp [recorder->currentWritePointer], data, dataToCopy * sizeof (uint8_t));

        recorder->currentWritePointer += dataToCopy;

        if (recorder->currentWritePointer == WAVE_BUFFER_SIZE) {
            // copy to the final buffer
            memcpy (recorder->audio_buffer, recorder->audio_buffer_tmp, WAVE_BUFFER_SIZE * sizeof (uint8_t));
            // reset the write pointer
            recorder->currentWritePointer = 0;
            recorder->fullframeReady = true;
        }

        // any data read left?
        if (dataToCopy < currentSize) {
            while ((currentSize - dataToCopy) > WAVE_BUFFER_SIZE)
                dataToCopy += WAVE_BUFFER_SIZE; // there's more than one full frame available, skip it entirely

            // data pending, keep it in the buffer
            memcpy (recorder->audio_buffer_tmp, data + dataToCopy, (currentSize - dataToCopy) * sizeof (uint8_t));

            recorder->currentWritePointer = currentSize - dataToCopy;
        }
    }

    if (pa_stream_drop (stream) != 0) {
        sLog.error ("Failed to drop data after peeking");
    }
}

void pa_server_info_cb (pa_context* ctx, const pa_server_info* info, void* userdata) {
    auto* recorder = static_cast<CPulseAudioPlaybackRecorder*> (userdata);

    pa_sample_spec spec;
    spec.format = PA_SAMPLE_U8;
    spec.rate = 44100;
    spec.channels = 1;

    if (recorder->getCaptureStream ()) {
        pa_stream_unref (recorder->getCaptureStream ());
        // get rid of the reference just in case
        recorder->setCaptureStream (nullptr);
    }

    pa_stream* captureStream = pa_stream_new (ctx, "output monitor", &spec, nullptr);

    // store the stream first, if the record start fails there'll still be a reference to it
    // so it can be free'd later
    recorder->setCaptureStream (captureStream),

        pa_stream_set_state_callback (captureStream, &pa_stream_notify_cb, userdata);
    pa_stream_set_read_callback (captureStream, &pa_stream_read_cb, userdata);

    std::string monitor_name (info->default_sink_name);
    monitor_name += ".monitor";
    if (pa_stream_connect_record (captureStream, monitor_name.c_str (), nullptr, PA_STREAM_NOFLAGS) != 0) {
        sLog.error ("Failed to connect to input for recording");
    }
}

void pa_context_subscribe_cb (pa_context* ctx, pa_subscription_event_type_t t, uint32_t idx, void* userdata) {
    // sink changes mean re-take the stream
    pa_context_get_server_info (ctx, &pa_server_info_cb, userdata);
}

void pa_context_notify_cb (pa_context* ctx, void* userdata) {
    switch (pa_context_get_state (ctx)) {
        case PA_CONTEXT_READY: {
            // set callback
            pa_context_set_subscribe_callback (ctx, pa_context_subscribe_cb, userdata);
            // set events mask and enable event callback.
            pa_operation* o = pa_context_subscribe (
                ctx, static_cast<pa_subscription_mask_t> (PA_SUBSCRIPTION_MASK_SINK | PA_SUBSCRIPTION_MASK_SOURCE),
                nullptr, nullptr);

            if (o)
                pa_operation_unref (o);

            // context being ready means to fetch the sink too
            pa_context_get_server_info (ctx, &pa_server_info_cb, userdata);

            break;
        }
        case PA_CONTEXT_FAILED:
            sLog.error ("PulseAudio context initialization failed. Audio processing is disabled");
            break;
    }
}

CPulseAudioPlaybackRecorder::CPulseAudioPlaybackRecorder () : m_captureStream (nullptr) {
    this->m_mainloop = pa_mainloop_new ();
    this->m_mainloopApi = pa_mainloop_get_api (this->m_mainloop);
    this->m_context = pa_context_new (this->m_mainloopApi, "wallpaperengine-audioprocessing");

    pa_context_set_state_callback (this->m_context, &pa_context_notify_cb, this);

    if (pa_context_connect (this->m_context, nullptr, PA_CONTEXT_NOFLAGS, nullptr) < 0) {
        sLog.error ("PulseAudio connection failed! Audio processing is disabled");
        return;
    }

    // wait until the context is ready
    while (pa_context_get_state (this->m_context) != PA_CONTEXT_READY)
        pa_mainloop_iterate (this->m_mainloop, 1, nullptr);
}

CPulseAudioPlaybackRecorder::~CPulseAudioPlaybackRecorder () {
    pa_context_disconnect (this->m_context);
    pa_mainloop_free (this->m_mainloop);
}

pa_stream* CPulseAudioPlaybackRecorder::getCaptureStream () {
    return this->m_captureStream;
}

void CPulseAudioPlaybackRecorder::setCaptureStream (pa_stream* stream) {
    this->m_captureStream = stream;
}

void CPulseAudioPlaybackRecorder::update () {
    pa_mainloop_iterate (this->m_mainloop, 0, nullptr);

    // interpolate current values to the destination
    for (int i = 0; i < 64; i++) {
        this->audio64 [i] = movetowards (this->audio64 [i], fft_destination64 [i], 0.1f);
        if (i >= 32)
            continue;
        this->audio32 [i] = movetowards (this->audio32 [i], fft_destination32 [i], 0.1f);
        if (i >= 16)
            continue;
        this->audio16 [i] = movetowards (this->audio16 [i], fft_destination16 [i], 0.1f);
    }

    if (!this->fullframeReady)
        return;

    this->fullframeReady = false;

    External::Android::doFft (audio_fft, audio_buffer);

    for (int i = 0; i < 64; i++) {
        const int paramInt = (i + 2) * 2;
        float f1 = audio_fft [paramInt];
        float f2 = audio_fft [paramInt + 1];
        f2 = f1 * f1 + f2 * f2;
        f1 = 0.0F;
        if (f2 > 0.0F)
            f1 = 0.35F * static_cast<float> (log10 (f2));

        this->fft_destination64 [i] =
            fmin (1.0F, f1 * static_cast<float> (2.0f - pow (M_E, (1.0F - i / 63.0F) * 1.0f - 0.5f)));
        this->fft_destination32 [i >> 1] =
            fmin (1.0F, f1 * static_cast<float> (2.0f - pow (M_E, (1.0F - i / 31.0F) * 1.0f - 0.5f)));
        this->fft_destination16 [i >> 2] =
            fmin (1.0F, f1 * static_cast<float> (2.0f - pow (M_E, (1.0F - i / 15.0F) * 1.0f - 0.5f)));
    }
}
} // namespace WallpaperEngine::Audio::Drivers::Recorders