Distortion.cpp

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// Copyright (c) 2008-2019 OpenShot Studios, LLC
//
// SPDX-License-Identifier: LGPL-3.0-or-later
 
#include "Distortion.h"
#include "Exceptions.h"
 
using namespace openshot;
 
Distortion::Distortion(): Distortion::Distortion(HARD_CLIPPING, 10, -10, 5) { }
 
Distortion::Distortion(openshot::DistortionType distortion_type,
                       Keyframe input_gain, Keyframe output_gain,
                       Keyframe tone):
    distortion_type(distortion_type), input_gain(input_gain),
    output_gain(output_gain), tone(tone)
{
    // Init effect properties
    init_effect_details();
}
 
// Init effect settings
void Distortion::init_effect_details()
{
    InitEffectInfo();
 
    info.class_name = "Distortion";
    info.name = "Distortion";
    info.description = "Alter the audio by clipping the signal.";
    info.has_audio = true;
    info.has_video = false;
}
 
 
// This method is required for all derived classes of EffectBase, and returns a
// modified openshot::Frame object
std::shared_ptr<openshot::Frame> Distortion::GetFrame(std::shared_ptr<openshot::Frame> frame, int64_t frame_number)
{
    filters.clear();
 
    for (int i = 0; i < frame->audio->getNumChannels(); ++i) {
        Filter* filter;
        filters.add (filter = new Filter());
    }
 
    updateFilters(frame_number);
 
    // Add distortion
    for (int channel = 0; channel < frame->audio->getNumChannels(); channel++)
    {
        auto *channel_data = frame->audio->getWritePointer(channel);
        float out;
 
        for (auto sample = 0; sample < frame->audio->getNumSamples(); ++sample)
        {
 
            const int input_gain_value = (int)input_gain.GetValue(frame_number);
            const int output_gain_value = (int)output_gain.GetValue(frame_number);
            const float in = channel_data[sample]*powf(10.0f, input_gain_value * 0.05f);
 
            // Use the current distortion type
            switch (distortion_type) {
 
                case HARD_CLIPPING: {
                    float threshold = 0.5f;
                    if (in > threshold)
                        out = threshold;
                    else if (in < -threshold)
                        out = -threshold;
                    else
                        out = in;
                    break;
                }
 
                case SOFT_CLIPPING: {
                    float threshold1 = 1.0f / 3.0f;
                    float threshold2 = 2.0f / 3.0f;
                    if (in > threshold2)
                        out = 1.0f;
                    else if (in > threshold1)
                        out = 1.0f - powf (2.0f - 3.0f * in, 2.0f) / 3.0f;
                    else if (in < -threshold2)
                        out = -1.0f;
                    else if (in < -threshold1)
                        out = -1.0f + powf (2.0f + 3.0f * in, 2.0f) / 3.0f;
                    else
                        out = 2.0f * in;
                    out *= 0.5f;
                    break;
                }
 
                case EXPONENTIAL: {
                    if (in > 0.0f)
                        out = 1.0f - expf (-in);
                    else
                        out = -1.0f + expf (in);
                    break;
                }
 
                case FULL_WAVE_RECTIFIER: {
                    out = fabsf (in);
                    break;
                }
 
                case HALF_WAVE_RECTIFIER: {
                    if (in > 0.0f)
                        out = in;
                    else
                        out = 0.0f;
                    break;
                }
            }
 
            float filtered = filters[channel]->processSingleSampleRaw(out);
            channel_data[sample] = filtered*powf(10.0f, output_gain_value * 0.05f);
        }
    }
 
    // return the modified frame
    return frame;
}
 
void Distortion::updateFilters(int64_t frame_number)
{
    double discrete_frequency = M_PI * 0.01;
    double gain = pow(10.0, (float)tone.GetValue(frame_number) * 0.05);
 
    for (int i = 0; i < filters.size(); ++i)
        filters[i]->updateCoefficients(discrete_frequency, gain);
}
 
// Generate JSON string of this object
std::string Distortion::Json() const {
 
    // Return formatted string
    return JsonValue().toStyledString();
}
 
void Distortion::Filter::updateCoefficients(const double discrete_frequency, const double gain)
{
    double tan_half_wc = tan(discrete_frequency / 2.0);
    double sqrt_gain = sqrt(gain);
 
    coefficients = juce::IIRCoefficients(/* b0 */ sqrt_gain * tan_half_wc + gain,
                                         /* b1 */ sqrt_gain * tan_half_wc - gain,
                                         /* b2 */ 0.0,
                                         /* a0 */ sqrt_gain * tan_half_wc + 1.0,
                                         /* a1 */ sqrt_gain * tan_half_wc - 1.0,
                                         /* a2 */ 0.0);
    setCoefficients(coefficients);
}
 
// Generate Json::Value for this object
Json::Value Distortion::JsonValue() const {
 
    // Create root json object
    Json::Value root = EffectBase::JsonValue(); // get parent properties
    root["type"] = info.class_name;
    root["distortion_type"] = distortion_type;
    root["input_gain"] = input_gain.JsonValue();
    root["output_gain"] = output_gain.JsonValue();
    root["tone"] = tone.JsonValue();
 
    // return JsonValue
    return root;
}
 
// Load JSON string into this object
void Distortion::SetJson(const std::string value) {
 
    // Parse JSON string into JSON objects
    try
    {
        const Json::Value root = openshot::stringToJson(value);
        // Set all values that match
        SetJsonValue(root);
    }
    catch (const std::exception& e)
    {
        // Error parsing JSON (or missing keys)
        throw InvalidJSON("JSON is invalid (missing keys or invalid data types)");
    }
}
 
// Load Json::Value into this object
void Distortion::SetJsonValue(const Json::Value root) {
 
    // Set parent data
    EffectBase::SetJsonValue(root);
 
    // Set data from Json (if key is found)
    if (!root["distortion_type"].isNull())
        distortion_type = (DistortionType)root["distortion_type"].asInt();
 
    if (!root["input_gain"].isNull())
        input_gain.SetJsonValue(root["input_gain"]);
 
    if (!root["output_gain"].isNull())
        output_gain.SetJsonValue(root["output_gain"]);
 
    if (!root["tone"].isNull())
        tone.SetJsonValue(root["tone"]);
}
 
// Get all properties for a specific frame
std::string Distortion::PropertiesJSON(int64_t requested_frame) const {
 
    // Generate JSON properties list
    Json::Value root = BasePropertiesJSON(requested_frame);
 
    // Keyframes
    root["distortion_type"] = add_property_json("Distortion Type", distortion_type, "int", "", NULL, 0, 3, false, requested_frame);
    root["input_gain"] = add_property_json("Input Gain (dB)", input_gain.GetValue(requested_frame), "int", "", &input_gain, -24, 24, false, requested_frame);
    root["output_gain"] = add_property_json("Output Gain (dB)", output_gain.GetValue(requested_frame), "int", "", &output_gain, -24, 24, false, requested_frame);
    root["tone"] = add_property_json("Tone (dB)", tone.GetValue(requested_frame), "int", "", &tone, -24, 24, false, requested_frame);
 
    // Add distortion_type choices (dropdown style)
    root["distortion_type"]["choices"].append(add_property_choice_json("Hard Clipping", HARD_CLIPPING, distortion_type));
    root["distortion_type"]["choices"].append(add_property_choice_json("Soft Clipping", SOFT_CLIPPING, distortion_type));
    root["distortion_type"]["choices"].append(add_property_choice_json("Exponential", EXPONENTIAL, distortion_type));
    root["distortion_type"]["choices"].append(add_property_choice_json("Full Wave Rectifier", FULL_WAVE_RECTIFIER, distortion_type));
    root["distortion_type"]["choices"].append(add_property_choice_json("Half Wave Rectifier", HALF_WAVE_RECTIFIER, distortion_type));
 
    // Return formatted string
    return root.toStyledString();
}