BeatSync.h

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// Copyright (c) 2008-2026 OpenShot Studios, LLC
//
// SPDX-License-Identifier: LGPL-3.0-or-later
 
#ifndef OPENSHOT_BEAT_SYNC_EFFECT_H
#define OPENSHOT_BEAT_SYNC_EFFECT_H
 
#include "../AnimatedCurve.h"
#include "../Color.h"
#include "../EffectBase.h"
#include "../Frame.h"
#include "../Json.h"
#include "../KeyFrame.h"
 
#include <memory>
#include <string>
 
namespace openshot
{
    class BeatSync : public EffectBase
    {
    private:
        void init_effect_details();
        float envelope_;         // persistent IIR envelope state
        int64_t last_frame_;     // detects seeks so we can reset envelope
 
    public:
        Color low_color;         // generated color at minimum response
        Color high_color;        // generated color at maximum response
        Keyframe intensity;      // audio gain multiplier (0.0–10.0)
        Keyframe threshold;      // energy floor below which nothing happens (0.0–1.0)
        Keyframe attack_ms;      // envelope rise time in milliseconds
        Keyframe decay_ms;       // envelope fall time in milliseconds
        Keyframe frequency_low;  // normalized frequency floor (0=20Hz, 1=20kHz)
        Keyframe frequency_high; // normalized frequency ceiling (0=20Hz, 1=20kHz)
        bool invert;             // flip: silence = max effect, loud = no effect
        AnimatedCurve response_curve; // maps normalized audio response to color blend
 
        BeatSync();
        BeatSync(Color color, Keyframe intensity);
 
        std::shared_ptr<openshot::Frame> GetFrame(int64_t frame_number) override { return GetFrame(std::make_shared<openshot::Frame>(), frame_number); }
        std::shared_ptr<openshot::Frame> GetFrame(std::shared_ptr<openshot::Frame> frame, int64_t frame_number) override;
 
        std::string Json() const override;
        void SetJson(const std::string value) override;
        Json::Value JsonValue() const override;
        void SetJsonValue(const Json::Value root) override;
        std::string PropertiesJSON(int64_t requested_frame) const override;
    };
}
 
#endif