AnalogTape.cpp

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// Copyright (c) 2008-2025 OpenShot Studios, LLC
//
// SPDX-License-Identifier: LGPL-3.0-or-later
 
#include "AnalogTape.h"
#include "Clip.h"
#include "Exceptions.h"
#include "ReaderBase.h"
#include "Timeline.h"
 
#include <algorithm>
#include <cmath>
 
using namespace openshot;
 
AnalogTape::AnalogTape()
        : tracking(0.55), bleed(0.65), softness(0.40), noise(0.50), stripe(0.25f),
            staticBands(0.20f), seed_offset(0) {
    init_effect_details();
}
 
AnalogTape::AnalogTape(Keyframe t, Keyframe b, Keyframe s, Keyframe n,
                                             Keyframe st, Keyframe sb, int seed)
        : tracking(t), bleed(b), softness(s), noise(n), stripe(st),
            staticBands(sb), seed_offset(seed) {
    init_effect_details();
}
 
void AnalogTape::init_effect_details() {
    InitEffectInfo();
    info.class_name = "AnalogTape";
    info.name = "Analog Tape";
    info.description = "Vintage home video wobble, bleed, and grain.";
    info.has_video = true;
    info.has_audio = false;
}
 
static inline float lerp(float a, float b, float t) { return a + (b - a) * t; }
 
std::shared_ptr<Frame> AnalogTape::GetFrame(std::shared_ptr<Frame> frame,
                                                                                        int64_t frame_number) {
    std::shared_ptr<QImage> img = frame->GetImage();
    int w = img->width();
    int h = img->height();
    int Uw = (w + 1) / 2;
    int stride = img->bytesPerLine() / 4;
    uint32_t *base = reinterpret_cast<uint32_t *>(img->bits());
 
    if (w != last_w || h != last_h) {
        last_w = w;
        last_h = h;
        Y.resize(w * h);
        U.resize(Uw * h);
        V.resize(Uw * h);
        tmpY.resize(w * h);
        tmpU.resize(Uw * h);
        tmpV.resize(Uw * h);
        dx.resize(h);
    }
 
 
#ifdef _OPENMP
#pragma omp parallel for
#endif
    for (int y = 0; y < h; ++y) {
        uint32_t *row = base + y * stride;
        float *yrow = &Y[y * w];
        float *urow = &U[y * Uw];
        float *vrow = &V[y * Uw];
        for (int x2 = 0; x2 < Uw; ++x2) {
            int x0 = x2 * 2;
            uint32_t p0 = row[x0];
            float r0 = ((p0 >> 16) & 0xFF) / 255.0f;
            float g0 = ((p0 >> 8) & 0xFF) / 255.0f;
            float b0 = (p0 & 0xFF) / 255.0f;
            float y0 = 0.299f * r0 + 0.587f * g0 + 0.114f * b0;
            float u0 = -0.14713f * r0 - 0.28886f * g0 + 0.436f * b0;
            float v0 = 0.615f * r0 - 0.51499f * g0 - 0.10001f * b0;
            yrow[x0] = y0;
 
            float u, v;
            if (x0 + 1 < w) {
                uint32_t p1 = row[x0 + 1];
                float r1 = ((p1 >> 16) & 0xFF) / 255.0f;
                float g1 = ((p1 >> 8) & 0xFF) / 255.0f;
                float b1 = (p1 & 0xFF) / 255.0f;
                float y1 = 0.299f * r1 + 0.587f * g1 + 0.114f * b1;
                float u1 = -0.14713f * r1 - 0.28886f * g1 + 0.436f * b1;
                float v1 = 0.615f * r1 - 0.51499f * g1 - 0.10001f * b1;
                yrow[x0 + 1] = y1;
                u = (u0 + u1) * 0.5f;
                v = (v0 + v1) * 0.5f;
            } else {
                u = u0;
                v = v0;
            }
            urow[x2] = u;
            vrow[x2] = v;
        }
    }
 
    Fraction fps(1, 1);
    Clip *clip = (Clip *)ParentClip();
    Timeline *timeline = nullptr;
    if (clip && clip->ParentTimeline())
        timeline = (Timeline *)clip->ParentTimeline();
    else if (ParentTimeline())
        timeline = (Timeline *)ParentTimeline();
    if (timeline)
        fps = timeline->info.fps;
    else if (clip && clip->Reader())
        fps = clip->Reader()->info.fps;
    double fps_d = fps.ToDouble();
    double t = fps_d > 0 ? frame_number / fps_d : frame_number;
 
    const float k_track = tracking.GetValue(frame_number);
    const float k_bleed = bleed.GetValue(frame_number);
    const float k_soft = softness.GetValue(frame_number);
    const float k_noise = noise.GetValue(frame_number);
    const float k_stripe = stripe.GetValue(frame_number);
    const float k_bands = staticBands.GetValue(frame_number);
 
    int r_y = std::round(lerp(0.0f, 2.0f, k_soft));
    if (k_noise > 0.6f)
        r_y = std::min(r_y, 1);
    if (r_y > 0) {
#ifdef _OPENMP
#pragma omp parallel for
#endif
        for (int y = 0; y < h; ++y)
            box_blur_row(&Y[y * w], &tmpY[y * w], w, r_y);
        Y.swap(tmpY);
    }
 
    float shift = lerp(0.0f, 2.5f, k_bleed);
    int r_c = std::round(lerp(0.0f, 3.0f, k_bleed));
    float sat = 1.0f - 0.30f * k_bleed;
    float shift_h = shift * 0.5f;
#ifdef _OPENMP
#pragma omp parallel for
#endif
    for (int y = 0; y < h; ++y) {
        const float *srcU = &U[y * Uw];
        const float *srcV = &V[y * Uw];
        float *dstU = &tmpU[y * Uw];
        float *dstV = &tmpV[y * Uw];
        for (int x = 0; x < Uw; ++x) {
            float xs = std::clamp(x - shift_h, 0.0f, float(Uw - 1));
            int x0 = int(xs);
            int x1 = std::min(x0 + 1, Uw - 1);
            float t = xs - x0;
            dstU[x] = srcU[x0] * (1 - t) + srcU[x1] * t;
            dstV[x] = srcV[x0] * (1 - t) + srcV[x1] * t;
        }
    }
    U.swap(tmpU);
    V.swap(tmpV);
 
    if (r_c > 0) {
#ifdef _OPENMP
#pragma omp parallel for
#endif
        for (int y = 0; y < h; ++y)
            box_blur_row(&U[y * Uw], &tmpU[y * Uw], Uw, r_c);
        U.swap(tmpU);
#ifdef _OPENMP
#pragma omp parallel for
#endif
        for (int y = 0; y < h; ++y)
            box_blur_row(&V[y * Uw], &tmpV[y * Uw], Uw, r_c);
        V.swap(tmpV);
    }
 
    uint32_t SEED = fnv1a_32(Id()) ^ (uint32_t)seed_offset;
        uint32_t schedSalt = (uint32_t)(k_bands * 64.0f) ^
                                                 ((uint32_t)(k_stripe * 64.0f) << 8) ^
                                                 ((uint32_t)(k_noise * 64.0f) << 16);
    uint32_t SCHED_SEED = SEED ^ fnv1a_32(schedSalt, 0x9e3779b9u);
    const float PI = 3.14159265358979323846f;
 
    float sigmaY = lerp(0.0f, 0.08f, k_noise);
    const float decay = 0.88f + 0.08f * k_noise;
    const float amp = 0.18f * k_noise;
    const float baseP = 0.0025f + 0.02f * k_noise;
 
    float Hfixed = lerp(0.0f, 0.12f * h, k_stripe);
    float Gfixed = 0.10f * k_stripe;
    float Nfixed = 1.0f + 1.5f * k_stripe;
 
    float rate = 0.4f * k_bands;
    int dur_frames = std::round(lerp(1.0f, 6.0f, k_bands));
    float Hburst = lerp(0.06f * h, 0.25f * h, k_bands);
    float Gburst = lerp(0.10f, 0.25f, k_bands);
    float sat_band = lerp(0.8f, 0.5f, k_bands);
    float Nburst = 1.0f + 2.0f * k_bands;
 
    struct Band { float center; double t0; };
    std::vector<Band> bands;
    if (k_bands > 0.0f && rate > 0.0f) {
        const double win_len = 0.25;
        int win_idx = int(t / win_len);
        double lambda = rate * win_len *
                                        (0.25 + 1.5f * row_density(SCHED_SEED, frame_number, 0));
        double prob_ge1 = 1.0 - std::exp(-lambda);
        double prob_ge2 = 1.0 - std::exp(-lambda) - lambda * std::exp(-lambda);
 
        auto spawn_band = [&](int kseed) {
            float r1 = hash01(SCHED_SEED, uint32_t(win_idx), 11 + kseed, 0);
            float start = r1 * win_len;
            float center =
                    hash01(SCHED_SEED, uint32_t(win_idx), 12 + kseed, 0) * (h - Hburst) +
                    0.5f * Hburst;
            double t0 = win_idx * win_len + start;
            double t1 = t0 + dur_frames / (fps_d > 0 ? fps_d : 1.0);
            if (t >= t0 && t < t1)
                bands.push_back({center, t0});
        };
 
        float r = hash01(SCHED_SEED, uint32_t(win_idx), 9, 0);
        if (r < prob_ge1)
            spawn_band(0);
        if (r < prob_ge2)
            spawn_band(1);
    }
 
    float ft = 2.0f;
    int kf = int(std::floor(t * ft));
    float a = float(t * ft - kf);
 
#ifdef _OPENMP
#pragma omp parallel for
#endif
    for (int y = 0; y < h; ++y) {
        float bandF = 0.0f;
        if (Hfixed > 0.0f && y >= h - Hfixed)
            bandF = (y - (h - Hfixed)) / std::max(1.0f, Hfixed);
        float burstF = 0.0f;
        for (const auto &b : bands) {
            float halfH = Hburst * 0.5f;
            float dist = std::abs(y - b.center);
            float profile = std::max(0.0f, 1.0f - dist / halfH);
            float life = float((t - b.t0) * fps_d);
            float env = (life < 1.0f)
                                            ? life
                                            : (life < dur_frames - 1 ? 1.0f
                                                                                            : std::max(0.0f, dur_frames - life));
            burstF = std::max(burstF, profile * env);
        }
 
        float sat_row = 1.0f - (1.0f - sat_band) * burstF;
        if (burstF > 0.0f && sat_row != 1.0f) {
            float *urow = &U[y * Uw];
            float *vrow = &V[y * Uw];
            for (int xh = 0; xh < Uw; ++xh) {
                urow[xh] *= sat_row;
                vrow[xh] *= sat_row;
            }
        }
 
        float rowBias = row_density(SEED, frame_number, y);
        float p = baseP * (0.25f + 1.5f * rowBias);
        p *= (1.0f + 1.5f * bandF + 2.0f * burstF);
 
        float hum = 0.008f * k_noise *
                                std::sin(2 * PI * (y * (6.0f / h) + 0.08f * t));
        uint32_t s0 = SEED ^ 0x9e37u * kf ^ 0x85ebu * y;
        uint32_t s1 = SEED ^ 0x9e37u * (kf + 1) ^ 0x85ebu * y ^ 0x1234567u;
        auto step = [](uint32_t &s) {
            s ^= s << 13;
            s ^= s >> 17;
            s ^= s << 5;
            return s;
        };
        float lift = Gfixed * bandF + Gburst * burstF;
        float rowSigma = sigmaY * (1 + (Nfixed - 1) * bandF +
                                                            (Nburst - 1) * burstF);
        float k = 0.15f + 0.35f * hash01(SEED, uint32_t(frame_number), y, 777);
        float sL = 0.0f, sR = 0.0f;
        for (int x = 0; x < w; ++x) {
            if (hash01(SEED, uint32_t(frame_number), y, x) < p)
                sL = 1.0f;
            if (hash01(SEED, uint32_t(frame_number), y, w - 1 - x) < p * 0.7f)
                sR = 1.0f;
            float n = ((step(s0) & 0xFFFFFF) / 16777215.0f) * (1 - a) +
                                ((step(s1) & 0xFFFFFF) / 16777215.0f) * a;
            int idx = y * w + x;
            float mt = std::clamp((Y[idx] - 0.2f) / (0.8f - 0.2f), 0.0f, 1.0f);
            float val = Y[idx] + lift + rowSigma * (2 * n - 1) *
                                                             (0.6f + 0.4f * mt) + hum;
            float streak = amp * (sL + sR);
            float newY = val + streak * (k + (1.0f - val));
            Y[idx] = std::clamp(newY, 0.0f, 1.0f);
            sL *= decay;
            sR *= decay;
        }
    }
 
    float A = lerp(0.0f, 3.0f, k_track); // pixels
    float f = lerp(0.25f, 1.2f, k_track); // Hz
    float Hsk = lerp(0.0f, 0.10f * h, k_track); // pixels
    float S = lerp(0.0f, 5.0f, k_track); // pixels
    float phase = 2 * PI * (f * t) + 0.7f * (SEED * 0.001f);
    for (int y = 0; y < h; ++y) {
        float base = A * std::sin(2 * PI * 0.0035f * y + phase);
        float skew = (y >= h - Hsk)
                                         ? S * ((y - (h - Hsk)) / std::max(1.0f, Hsk))
                                         : 0.0f;
        dx[y] = base + skew;
    }
 
    auto remap_line = [&](const float *src, float *dst, int width, float scale) {
#ifdef _OPENMP
#pragma omp parallel for
#endif
        for (int y = 0; y < h; ++y) {
            float off = dx[y] * scale;
            const float *s = src + y * width;
            float *d = dst + y * width;
            int start = std::max(0, int(std::ceil(-off)));
            int end = std::min(width, int(std::floor(width - off)));
            float xs = start + off;
            int x0 = int(xs);
            float t = xs - x0;
            for (int x = start; x < end; ++x) {
                int x1 = x0 + 1;
                d[x] = s[x0] * (1 - t) + s[x1] * t;
                xs += 1.0f;
                x0 = int(xs);
                t = xs - x0;
            }
            for (int x = 0; x < start; ++x)
                d[x] = s[0];
            for (int x = end; x < width; ++x)
                d[x] = s[width - 1];
        }
    };
 
    remap_line(Y.data(), tmpY.data(), w, 1.0f);
    Y.swap(tmpY);
    remap_line(U.data(), tmpU.data(), Uw, 0.5f);
    U.swap(tmpU);
    remap_line(V.data(), tmpV.data(), Uw, 0.5f);
    V.swap(tmpV);
 
#ifdef _OPENMP
#pragma omp parallel for
#endif
    for (int y = 0; y < h; ++y) {
        float *yrow = &Y[y * w];
        float *urow = &U[y * Uw];
        float *vrow = &V[y * Uw];
        uint32_t *row = base + y * stride;
        for (int x = 0; x < w; ++x) {
            float xs = x * 0.5f;
            int x0 = int(xs);
            int x1 = std::min(x0 + 1, Uw - 1);
            float t = xs - x0;
            float u = (urow[x0] * (1 - t) + urow[x1] * t) * sat;
            float v = (vrow[x0] * (1 - t) + vrow[x1] * t) * sat;
            float yv = yrow[x];
            float r = yv + 1.13983f * v;
            float g = yv - 0.39465f * u - 0.58060f * v;
            float b = yv + 2.03211f * u;
            int R = int(std::clamp(r, 0.0f, 1.0f) * 255.0f);
            int G = int(std::clamp(g, 0.0f, 1.0f) * 255.0f);
            int B = int(std::clamp(b, 0.0f, 1.0f) * 255.0f);
            uint32_t A = row[x] & 0xFF000000u;
            row[x] = A | (R << 16) | (G << 8) | B;
        }
    }
 
    return frame;
}
 
// JSON
std::string AnalogTape::Json() const { return JsonValue().toStyledString(); }
 
Json::Value AnalogTape::JsonValue() const {
    Json::Value root = EffectBase::JsonValue();
    root["type"] = info.class_name;
    root["tracking"] = tracking.JsonValue();
    root["bleed"] = bleed.JsonValue();
    root["softness"] = softness.JsonValue();
    root["noise"] = noise.JsonValue();
    root["stripe"] = stripe.JsonValue();
    root["static_bands"] = staticBands.JsonValue();
    root["seed_offset"] = seed_offset;
    return root;
}
 
void AnalogTape::SetJson(const std::string value) {
    try {
        Json::Value root = openshot::stringToJson(value);
        SetJsonValue(root);
    } catch (const std::exception &) {
        throw InvalidJSON("JSON is invalid (missing keys or invalid data types)");
    }
}
 
void AnalogTape::SetJsonValue(const Json::Value root) {
    EffectBase::SetJsonValue(root);
    if (!root["tracking"].isNull())
        tracking.SetJsonValue(root["tracking"]);
    if (!root["bleed"].isNull())
        bleed.SetJsonValue(root["bleed"]);
    if (!root["softness"].isNull())
        softness.SetJsonValue(root["softness"]);
    if (!root["noise"].isNull())
        noise.SetJsonValue(root["noise"]);
    if (!root["stripe"].isNull())
        stripe.SetJsonValue(root["stripe"]);
    if (!root["static_bands"].isNull())
        staticBands.SetJsonValue(root["static_bands"]);
    if (!root["seed_offset"].isNull())
        seed_offset = root["seed_offset"].asInt();
}
 
std::string AnalogTape::PropertiesJSON(int64_t requested_frame) const {
    Json::Value root = BasePropertiesJSON(requested_frame);
    root["tracking"] =
            add_property_json("Tracking", tracking.GetValue(requested_frame), "float",
                                                "", &tracking, 0, 1, false, requested_frame);
    root["bleed"] =
            add_property_json("Bleed", bleed.GetValue(requested_frame), "float", "",
                                                &bleed, 0, 1, false, requested_frame);
    root["softness"] =
            add_property_json("Softness", softness.GetValue(requested_frame), "float",
                                                "", &softness, 0, 1, false, requested_frame);
    root["noise"] =
            add_property_json("Noise", noise.GetValue(requested_frame), "float", "",
                                                &noise, 0, 1, false, requested_frame);
    root["stripe"] =
            add_property_json("Stripe", stripe.GetValue(requested_frame), "float",
                                                "Bottom tracking stripe brightness and noise.",
                                                &stripe, 0, 1, false, requested_frame);
    root["static_bands"] =
            add_property_json("Static Bands", staticBands.GetValue(requested_frame),
                                                "float",
                                                "Short bright static bands and extra dropouts.",
                                                &staticBands, 0, 1, false, requested_frame);
    root["seed_offset"] =
            add_property_json("Seed Offset", seed_offset, "int", "", NULL, 0, 1000,
                                                false, requested_frame);
    return root.toStyledString();
}