Timeline.cpp

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// Copyright (c) 2008-2019 OpenShot Studios, LLC
//
// SPDX-License-Identifier: LGPL-3.0-or-later
 
#include "Timeline.h"
 
#include "CacheBase.h"
#include "CacheDisk.h"
#include "CacheMemory.h"
#include "CrashHandler.h"
#include "FrameMapper.h"
#include "Exceptions.h"
#include "effects/Mask.h"
 
#include <algorithm>
#include <QDir>
#include <QFileInfo>
#include <QRegularExpression>
#include <unordered_map>
#include <cmath>
#include <cstdint>
 
using namespace openshot;
 
// Default Constructor for the timeline (which sets the canvas width and height)
Timeline::Timeline(int width, int height, Fraction fps, int sample_rate, int channels, ChannelLayout channel_layout) :
        is_open(false), auto_map_clips(true), managed_cache(true), path(""), max_time(0.0), cache_epoch(0)
{
    // Create CrashHandler and Attach (incase of errors)
    CrashHandler::Instance();
 
    // Init viewport size (curve based, because it can be animated)
    viewport_scale = Keyframe(100.0);
    viewport_x = Keyframe(0.0);
    viewport_y = Keyframe(0.0);
 
    // Init background color
    color.red = Keyframe(0.0);
    color.green = Keyframe(0.0);
    color.blue = Keyframe(0.0);
 
    // Init FileInfo struct (clear all values)
    info.width = width;
    info.height = height;
    preview_width = info.width;
    preview_height = info.height;
    info.fps = fps;
    info.sample_rate = sample_rate;
    info.channels = channels;
    info.channel_layout = channel_layout;
    info.video_timebase = fps.Reciprocal();
    info.duration = 60 * 30; // 30 minute default duration
    info.has_audio = true;
    info.has_video = true;
    info.video_length = info.fps.ToFloat() * info.duration;
    info.display_ratio = openshot::Fraction(width, height);
    info.display_ratio.Reduce();
    info.pixel_ratio = openshot::Fraction(1, 1);
    info.acodec = "openshot::timeline";
    info.vcodec = "openshot::timeline";
 
    // Init max image size
    SetMaxSize(info.width, info.height);
 
    // Init cache
    final_cache = new CacheMemory();
    const int cache_frames = std::max(Settings::Instance()->CACHE_MIN_FRAMES, OPEN_MP_NUM_PROCESSORS * 4);
    final_cache->SetMaxBytesFromInfo(cache_frames, info.width, info.height, info.sample_rate, info.channels);
}
 
// Delegating constructor that copies parameters from a provided ReaderInfo
Timeline::Timeline(const ReaderInfo info) : Timeline::Timeline(
    info.width, info.height, info.fps, info.sample_rate,
    info.channels, info.channel_layout) {}
 
// Constructor for the timeline (which loads a JSON structure from a file path, and initializes a timeline)
Timeline::Timeline(const std::string& projectPath, bool convert_absolute_paths) :
        is_open(false), auto_map_clips(true), managed_cache(true), path(projectPath), max_time(0.0), cache_epoch(0) {
 
    // Create CrashHandler and Attach (incase of errors)
    CrashHandler::Instance();
 
    // Init final cache as NULL (will be created after loading json)
    final_cache = NULL;
 
    // Init viewport size (curve based, because it can be animated)
    viewport_scale = Keyframe(100.0);
    viewport_x = Keyframe(0.0);
    viewport_y = Keyframe(0.0);
 
    // Init background color
    color.red = Keyframe(0.0);
    color.green = Keyframe(0.0);
    color.blue = Keyframe(0.0);
 
    // Check if path exists
    QFileInfo filePath(QString::fromStdString(path));
    if (!filePath.exists()) {
        throw InvalidFile("Timeline project file could not be opened.", path);
    }
 
    // Check OpenShot Install Path exists
    Settings *s = Settings::Instance();
    QDir openshotPath(QString::fromStdString(s->PATH_OPENSHOT_INSTALL));
    if (!openshotPath.exists()) {
        throw InvalidFile("PATH_OPENSHOT_INSTALL could not be found.", s->PATH_OPENSHOT_INSTALL);
    }
    QDir openshotTransPath(openshotPath.filePath("transitions"));
    if (!openshotTransPath.exists()) {
        throw InvalidFile("PATH_OPENSHOT_INSTALL/transitions could not be found.", openshotTransPath.path().toStdString());
    }
 
    // Determine asset path
    QString asset_name = filePath.baseName().left(30) + "_assets";
    QDir asset_folder(filePath.dir().filePath(asset_name));
    if (!asset_folder.exists()) {
        // Create directory if needed
        asset_folder.mkpath(".");
    }
 
    // Load UTF-8 project file into QString
    QFile projectFile(QString::fromStdString(path));
    projectFile.open(QFile::ReadOnly);
    QString projectContents = QString::fromUtf8(projectFile.readAll());
 
    // Convert all relative paths into absolute paths (if requested)
    if (convert_absolute_paths) {
 
        // Find all "image" or "path" references in JSON (using regex). Must loop through match results
        // due to our path matching needs, which are not possible with the QString::replace() function.
        QRegularExpression allPathsRegex(QStringLiteral("\"(image|path)\":.*?\"(.*?)\""));
        std::vector<QRegularExpressionMatch> matchedPositions;
        QRegularExpressionMatchIterator i = allPathsRegex.globalMatch(projectContents);
        while (i.hasNext()) {
            QRegularExpressionMatch match = i.next();
            if (match.hasMatch()) {
                // Push all match objects into a vector (so we can reverse them later)
                matchedPositions.push_back(match);
            }
        }
 
        // Reverse the matches (bottom of file to top, so our replacements don't break our match positions)
        std::vector<QRegularExpressionMatch>::reverse_iterator itr;
        for (itr = matchedPositions.rbegin(); itr != matchedPositions.rend(); itr++) {
            QRegularExpressionMatch match = *itr;
            QString relativeKey = match.captured(1); // image or path
            QString relativePath = match.captured(2); // relative file path
            QString absolutePath = "";
 
            // Find absolute path of all path, image (including special replacements of @assets and @transitions)
            if (relativePath.startsWith("@assets")) {
                absolutePath = QFileInfo(asset_folder.absoluteFilePath(relativePath.replace("@assets", "."))).canonicalFilePath();
            } else if (relativePath.startsWith("@transitions")) {
                absolutePath = QFileInfo(openshotTransPath.absoluteFilePath(relativePath.replace("@transitions", "."))).canonicalFilePath();
            } else {
                absolutePath = QFileInfo(filePath.absoluteDir().absoluteFilePath(relativePath)).canonicalFilePath();
            }
 
            // Replace path in JSON content, if an absolute path was successfully found
            if (!absolutePath.isEmpty()) {
                projectContents.replace(match.capturedStart(0), match.capturedLength(0), "\"" + relativeKey + "\": \"" + absolutePath + "\"");
            }
        }
        // Clear matches
        matchedPositions.clear();
    }
 
    // Set JSON of project
    SetJson(projectContents.toStdString());
 
    // Calculate valid duration and set has_audio and has_video
    // based on content inside this Timeline's clips.
    float calculated_duration = 0.0;
    for (auto clip : clips)
    {
        float clip_last_frame = clip->Position() + clip->Duration();
        if (clip_last_frame > calculated_duration)
            calculated_duration = clip_last_frame;
        if (clip->Reader() && clip->Reader()->info.has_audio)
            info.has_audio = true;
        if (clip->Reader() && clip->Reader()->info.has_video)
            info.has_video = true;
 
    }
    info.video_length = calculated_duration * info.fps.ToFloat();
    info.duration = calculated_duration;
 
    // Init FileInfo settings
    info.acodec = "openshot::timeline";
    info.vcodec = "openshot::timeline";
    info.video_timebase = info.fps.Reciprocal();
    info.has_video = true;
    info.has_audio = true;
 
    // Init max image size
    SetMaxSize(info.width, info.height);
 
    // Init cache
    final_cache = new CacheMemory();
    const int cache_frames = std::max(Settings::Instance()->CACHE_MIN_FRAMES, OPEN_MP_NUM_PROCESSORS * 4);
    final_cache->SetMaxBytesFromInfo(cache_frames, info.width, info.height, info.sample_rate, info.channels);
}
 
Timeline::~Timeline() {
    if (is_open) {
        // Auto Close if not already
        Close();
    }
 
    // Remove all clips, effects, and frame mappers
    Clear();
 
    // Destroy previous cache (if managed by timeline)
    if (managed_cache && final_cache) {
        delete final_cache;
        final_cache = NULL;
    }
}
 
// Add to the tracked_objects map a pointer to a tracked object (TrackedObjectBBox)
void Timeline::AddTrackedObject(std::shared_ptr<openshot::TrackedObjectBase> trackedObject){
 
    // Search for the tracked object on the map
    auto iterator = tracked_objects.find(trackedObject->Id());
 
    if (iterator != tracked_objects.end()){
        // Tracked object's id already present on the map, overwrite it
        iterator->second = trackedObject;
    }
    else{
        // Tracked object's id not present -> insert it on the map
        tracked_objects[trackedObject->Id()] = trackedObject;
    }
 
    return;
}
 
// Return tracked object pointer by it's id
std::shared_ptr<openshot::TrackedObjectBase> Timeline::GetTrackedObject(std::string id) const{
 
    // Search for the tracked object on the map
    auto iterator = tracked_objects.find(id);
 
    if (iterator != tracked_objects.end()){
        // Id found, return the pointer to the tracked object
        std::shared_ptr<openshot::TrackedObjectBase> trackedObject = iterator->second;
        return trackedObject;
    }
    else {
        // Id not found, return a null pointer
        return nullptr;
    }
}
 
// Return the ID's of the tracked objects as a list of strings
std::list<std::string> Timeline::GetTrackedObjectsIds() const{
 
    // Create a list of strings
    std::list<std::string> trackedObjects_ids;
 
    // Iterate through the tracked_objects map
    for (auto const& it: tracked_objects){
        // Add the IDs to the list
        trackedObjects_ids.push_back(it.first);
    }
 
    return trackedObjects_ids;
}
 
#ifdef USE_OPENCV
// Return the trackedObject's properties as a JSON string
std::string Timeline::GetTrackedObjectValues(std::string id, int64_t frame_number) const {
 
    // Initialize the JSON object
    Json::Value trackedObjectJson;
 
    // Search for the tracked object on the map
    auto iterator = tracked_objects.find(id);
 
    if (iterator != tracked_objects.end())
    {
        // Id found, Get the object pointer and cast it as a TrackedObjectBBox
        std::shared_ptr<TrackedObjectBBox> trackedObject = std::static_pointer_cast<TrackedObjectBBox>(iterator->second);
 
        // Get the trackedObject values for it's first frame
        if (trackedObject->ExactlyContains(frame_number)){
            BBox box = trackedObject->GetBox(frame_number);
            float x1 = box.cx - (box.width/2);
            float y1 = box.cy - (box.height/2);
            float x2 = box.cx + (box.width/2);
            float y2 = box.cy + (box.height/2);
            float rotation = box.angle;
 
            trackedObjectJson["x1"] = x1;
            trackedObjectJson["y1"] = y1;
            trackedObjectJson["x2"] = x2;
            trackedObjectJson["y2"] = y2;
            trackedObjectJson["rotation"] = rotation;
 
        } else {
            BBox box = trackedObject->BoxVec.begin()->second;
            float x1 = box.cx - (box.width/2);
            float y1 = box.cy - (box.height/2);
            float x2 = box.cx + (box.width/2);
            float y2 = box.cy + (box.height/2);
            float rotation = box.angle;
 
            trackedObjectJson["x1"] = x1;
            trackedObjectJson["y1"] = y1;
            trackedObjectJson["x2"] = x2;
            trackedObjectJson["y2"] = y2;
            trackedObjectJson["rotation"] = rotation;
        }
 
    }
    else {
        // Id not found, return all 0 values
        trackedObjectJson["x1"] = 0;
        trackedObjectJson["y1"] = 0;
        trackedObjectJson["x2"] = 0;
        trackedObjectJson["y2"] = 0;
        trackedObjectJson["rotation"] = 0;
    }
 
    return trackedObjectJson.toStyledString();
}
#endif
 
// Add an openshot::Clip to the timeline
void Timeline::AddClip(Clip* clip)
{
    // Get lock (prevent getting frames while this happens)
    const std::lock_guard<std::recursive_mutex> guard(getFrameMutex);
 
    // Assign timeline to clip
    clip->ParentTimeline(this);
 
    // Clear cache of clip and nested reader (if any)
    if (clip->Reader() && clip->Reader()->GetCache())
        clip->Reader()->GetCache()->Clear();
 
    // All clips should be converted to the frame rate of this timeline
    if (auto_map_clips) {
        // Apply framemapper (or update existing framemapper)
        apply_mapper_to_clip(clip);
    }
 
    InvalidateCacheForClip(clip);
 
    // Add clip to list
    clips.push_back(clip);
 
    // Sort clips
    sort_clips();
}
 
// Add an effect to the timeline
void Timeline::AddEffect(EffectBase* effect)
{
    // Get lock (prevent getting frames while this happens)
    const std::lock_guard<std::recursive_mutex> guard(getFrameMutex);
 
    // Assign timeline to effect
    effect->ParentTimeline(this);
 
    // Add effect to list
    effects.push_back(effect);
 
    // Sort effects
    sort_effects();
}
 
// Remove an effect from the timeline
void Timeline::RemoveEffect(EffectBase* effect)
{
    // Get lock (prevent getting frames while this happens)
    const std::lock_guard<std::recursive_mutex> guard(getFrameMutex);
 
    effects.remove(effect);
 
    // Delete effect object (if timeline allocated it)
    if (allocated_effects.count(effect)) {
        allocated_effects.erase(effect); // erase before nulling the pointer
        delete effect;
        effect = NULL;
    }
 
    // Sort effects
    sort_effects();
}
 
// Remove an openshot::Clip to the timeline
void Timeline::RemoveClip(Clip* clip)
{
    // Get lock (prevent getting frames while this happens)
    const std::lock_guard<std::recursive_mutex> guard(getFrameMutex);
 
    clips.remove(clip);
    
    // Delete clip object (if timeline allocated it)
    if (allocated_clips.count(clip)) {
        allocated_clips.erase(clip);         // erase before nulling the pointer
        delete clip;
        clip = NULL;
    }
 
    // Sort clips
    sort_clips();
}
 
// Look up a clip
openshot::Clip* Timeline::GetClip(const std::string& id)
{
    // Find the matching clip (if any)
    for (const auto& clip : clips) {
        if (clip->Id() == id) {
            return clip;
        }
    }
    return nullptr;
}
 
// Look up a timeline effect
openshot::EffectBase* Timeline::GetEffect(const std::string& id)
{
    // Find the matching effect (if any)
    for (const auto& effect : effects) {
        if (effect->Id() == id) {
            return effect;
        }
    }
    return nullptr;
}
 
openshot::EffectBase* Timeline::GetClipEffect(const std::string& id)
{
    // Search all clips for matching effect ID
    for (const auto& clip : clips) {
        const auto e = clip->GetEffect(id);
        if (e != nullptr) {
            return e;
        }
    }
    return nullptr;
}
 
// Return the list of effects on all clips
std::list<openshot::EffectBase*> Timeline::ClipEffects() const {
 
    // Initialize the list
    std::list<EffectBase*> timelineEffectsList;
 
    // Loop through all clips
    for (const auto& clip : clips) {
 
        // Get the clip's list of effects
        std::list<EffectBase*> clipEffectsList = clip->Effects();
 
        // Append the clip's effects to the list
        timelineEffectsList.insert(timelineEffectsList.end(), clipEffectsList.begin(), clipEffectsList.end());
    }
 
    return timelineEffectsList;
}
 
// Compute the end time of the latest timeline element
double Timeline::GetMaxTime() {
    // Return cached max_time variable (threadsafe)
    return max_time;
}
 
// Compute the highest frame# based on the latest time and FPS
int64_t Timeline::GetMaxFrame() {
    const double fps = info.fps.ToDouble();
    const double t = GetMaxTime();
    const double frames = t * fps;
    constexpr double frame_boundary_epsilon = 1e-4;
 
    // End is exclusive; ignore tiny float overshoots at frame boundaries.
    if (frames > 0.0 && frames < frame_boundary_epsilon)
        return 1;
    return static_cast<int64_t>(std::ceil(frames - frame_boundary_epsilon));
}
 
// Compute the first frame# based on the first clip position
int64_t Timeline::GetMinFrame() {
    const double fps = info.fps.ToDouble();
    const double t = GetMinTime();
    // Inclusive start -> floor at the start boundary, then 1-index
    return static_cast<int64_t>(std::floor(t * fps)) + 1;
}
 
// Compute the start time of the first timeline clip
double Timeline::GetMinTime() {
    // Return cached min_time variable (threadsafe)
    return min_time;
}
 
// Apply a FrameMapper to a clip which matches the settings of this timeline
void Timeline::apply_mapper_to_clip(Clip* clip)
{
    // Serialize mapper replacement/reconfiguration with active frame generation.
    const std::lock_guard<std::recursive_mutex> guard(getFrameMutex);
 
    // Determine type of reader
    ReaderBase* clip_reader = NULL;
    if (clip->Reader()->Name() == "FrameMapper")
    {
        // Get the existing reader
        clip_reader = (ReaderBase*) clip->Reader();
 
        // Update the mapping
        FrameMapper* clip_mapped_reader = (FrameMapper*) clip_reader;
        clip_mapped_reader->ChangeMapping(info.fps, PULLDOWN_NONE, info.sample_rate, info.channels, info.channel_layout);
 
    } else {
 
        // Create a new FrameMapper to wrap the current reader
        FrameMapper* mapper = new FrameMapper(clip->Reader(), info.fps, PULLDOWN_NONE, info.sample_rate, info.channels, info.channel_layout);
        allocated_frame_mappers.insert(mapper);
        clip_reader = (ReaderBase*) mapper;
    }
 
    // Update clip reader
    clip->Reader(clip_reader);
}
 
// Apply the timeline's framerate and samplerate to all clips
void Timeline::ApplyMapperToClips()
{
    // Clear all cached frames
    ClearAllCache();
 
    // Loop through all clips
    for (auto clip : clips)
    {
        // Apply framemapper (or update existing framemapper)
        apply_mapper_to_clip(clip);
    }
}
 
// Calculate time of a frame number, based on a framerate
double Timeline::calculate_time(int64_t number, Fraction rate)
{
    // Get float version of fps fraction
    double raw_fps = rate.ToFloat();
 
    // Return the time (in seconds) of this frame
    return double(number - 1) / raw_fps;
}
 
// Apply effects to the source frame (if any)
std::shared_ptr<Frame> Timeline::apply_effects(std::shared_ptr<Frame> frame, int64_t timeline_frame_number, int layer, TimelineInfoStruct* options)
{
    // Debug output
    ZmqLogger::Instance()->AppendDebugMethod(
        "Timeline::apply_effects",
        "frame->number", frame->number,
        "timeline_frame_number", timeline_frame_number,
        "layer", layer);
 
    // Find Effects at this position and layer
    for (auto effect : effects)
    {
        // Does clip intersect the current requested time
        const double fpsD = info.fps.ToDouble();
        int64_t effect_start_position = static_cast<int64_t>(std::llround(effect->Position() * fpsD)) + 1;
        int64_t effect_end_position   = static_cast<int64_t>(std::llround((effect->Position() + effect->Duration()) * fpsD));
 
        bool does_effect_intersect = (effect_start_position <= timeline_frame_number && effect_end_position >= timeline_frame_number && effect->Layer() == layer);
 
        // Clip is visible
        if (does_effect_intersect)
        {
            // Determine the frame needed for this clip (based on the position on the timeline)
            int64_t effect_start_frame  = static_cast<int64_t>(std::llround(effect->Start() * fpsD)) + 1;
            int64_t effect_frame_number = timeline_frame_number - effect_start_position + effect_start_frame;
 
            if (!options->is_top_clip)
                continue; // skip effect, if overlapped/covered by another clip on same layer
 
            if (options->is_before_clip_keyframes != effect->info.apply_before_clip)
                continue; // skip effect, if this filter does not match
 
            // Debug output
            ZmqLogger::Instance()->AppendDebugMethod(
                "Timeline::apply_effects (Process Effect)",
                "effect_frame_number", effect_frame_number,
                "does_effect_intersect", does_effect_intersect);
 
            // Apply the effect to this frame
            frame = effect->ProcessFrame(frame, effect_frame_number);
        }
 
    } // end effect loop
 
    // Return modified frame
    return frame;
}
 
// Get or generate a blank frame
std::shared_ptr<Frame> Timeline::GetOrCreateFrame(std::shared_ptr<Frame> background_frame, Clip* clip, int64_t number, openshot::TimelineInfoStruct* options)
{
    std::shared_ptr<Frame> new_frame;
 
    // Init some basic properties about this frame
    int samples_in_frame = Frame::GetSamplesPerFrame(number, info.fps, info.sample_rate, info.channels);
 
    try {
        // Debug output
        ZmqLogger::Instance()->AppendDebugMethod(
            "Timeline::GetOrCreateFrame (from reader)",
            "number", number,
            "samples_in_frame", samples_in_frame);
 
        // Attempt to get a frame (but this could fail if a reader has just been closed)
        new_frame = std::shared_ptr<Frame>(clip->GetFrame(background_frame, number, options));
 
        // Return real frame
        return new_frame;
 
    } catch (const ReaderClosed & e) {
        // ...
    } catch (const OutOfBoundsFrame & e) {
        // ...
    }
 
    // Debug output
    ZmqLogger::Instance()->AppendDebugMethod(
        "Timeline::GetOrCreateFrame (create blank)",
        "number", number,
        "samples_in_frame", samples_in_frame);
 
    // Create blank frame
    return new_frame;
}
 
// Process a new layer of video or audio
void Timeline::add_layer(std::shared_ptr<Frame> new_frame, Clip* source_clip, int64_t clip_frame_number, bool is_top_clip, float max_volume)
{
    // Create timeline options (with details about this current frame request)
    TimelineInfoStruct options{};
    options.is_top_clip = is_top_clip;
    options.is_before_clip_keyframes = true;
 
    // Get the clip's frame, composited on top of the current timeline frame
    std::shared_ptr<Frame> source_frame;
    source_frame = GetOrCreateFrame(new_frame, source_clip, clip_frame_number, &options);
 
    // No frame found... so bail
    if (!source_frame)
        return;
 
    // Debug output
    ZmqLogger::Instance()->AppendDebugMethod(
        "Timeline::add_layer",
        "new_frame->number", new_frame->number,
        "clip_frame_number", clip_frame_number);
 
    /* COPY AUDIO - with correct volume */
    if (source_clip->Reader()->info.has_audio) {
        // Debug output
        ZmqLogger::Instance()->AppendDebugMethod(
            "Timeline::add_layer (Copy Audio)",
            "source_clip->Reader()->info.has_audio", source_clip->Reader()->info.has_audio,
            "source_frame->GetAudioChannelsCount()", source_frame->GetAudioChannelsCount(),
            "info.channels", info.channels,
            "clip_frame_number", clip_frame_number);
 
        if (source_frame->GetAudioChannelsCount() == info.channels && source_clip->has_audio.GetInt(clip_frame_number) != 0)
        {
            // Ensure timeline frame matches the source samples once per frame
            if (new_frame->GetAudioSamplesCount() != source_frame->GetAudioSamplesCount()){
                new_frame->ResizeAudio(info.channels, source_frame->GetAudioSamplesCount(), info.sample_rate, info.channel_layout);
            }
 
            // Apply transition-driven equal-power audio fades for clips covered by a Mask transition.
            const auto transition_audio_gains = ResolveTransitionAudioGains(source_clip, new_frame->number, is_top_clip);
 
            for (int channel = 0; channel < source_frame->GetAudioChannelsCount(); channel++)
            {
                // Get volume from previous frame and this frame
                float previous_volume = source_clip->volume.GetValue(clip_frame_number - 1);
                float volume = source_clip->volume.GetValue(clip_frame_number);
                previous_volume *= transition_audio_gains.first;
                volume *= transition_audio_gains.second;
                int channel_filter = source_clip->channel_filter.GetInt(clip_frame_number); // optional channel to filter (if not -1)
                int channel_mapping = source_clip->channel_mapping.GetInt(clip_frame_number); // optional channel to map this channel to (if not -1)
 
                // Apply volume mixing strategy
                if (source_clip->mixing == VOLUME_MIX_AVERAGE && max_volume > 1.0) {
                    // Don't allow this clip to exceed 100% (divide volume equally between all overlapping clips with volume
                    previous_volume = previous_volume / max_volume;
                    volume = volume / max_volume;
                }
                else if (source_clip->mixing == VOLUME_MIX_REDUCE && max_volume > 1.0) {
                    // Reduce clip volume by a bit, hoping it will prevent exceeding 100% (but it is very possible it will)
                    previous_volume = previous_volume * 0.77;
                    volume = volume * 0.77;
                }
 
                // If channel filter enabled, check for correct channel (and skip non-matching channels)
                if (channel_filter != -1 && channel_filter != channel)
                    continue; // skip to next channel
 
                // If no volume on this frame or previous frame, do nothing
                if (previous_volume == 0.0 && volume == 0.0)
                    continue; // skip to next channel
 
                // If channel mapping disabled, just use the current channel
                if (channel_mapping == -1)
                    channel_mapping = channel;
 
                // Apply ramp to source frame (if needed)
                if (!isEqual(previous_volume, 1.0) || !isEqual(volume, 1.0))
                    source_frame->ApplyGainRamp(channel_mapping, 0, source_frame->GetAudioSamplesCount(), previous_volume, volume);
 
                // Copy audio samples (and set initial volume).  Mix samples with existing audio samples.  The gains are added together, to
                // be sure to set the gain's correctly, so the sum does not exceed 1.0 (of audio distortion will happen).
                new_frame->AddAudio(false, channel_mapping, 0, source_frame->GetAudioSamples(channel), source_frame->GetAudioSamplesCount(), 1.0);
            }
        }
        else
            // Debug output
            ZmqLogger::Instance()->AppendDebugMethod(
                "Timeline::add_layer (No Audio Copied - Wrong # of Channels)",
                "source_clip->Reader()->info.has_audio",
                    source_clip->Reader()->info.has_audio,
                "source_frame->GetAudioChannelsCount()",
                    source_frame->GetAudioChannelsCount(),
                "info.channels", info.channels,
                "clip_frame_number", clip_frame_number);
    }
 
    // Debug output
    ZmqLogger::Instance()->AppendDebugMethod(
        "Timeline::add_layer (Transform: Composite Image Layer: Completed)",
        "source_frame->number", source_frame->number,
        "new_frame->GetImage()->width()", new_frame->GetWidth(),
        "new_frame->GetImage()->height()", new_frame->GetHeight());
}
 
// Update the list of 'opened' clips
void Timeline::update_open_clips(Clip *clip, bool does_clip_intersect)
{
    // Get lock (prevent getting frames while this happens)
    const std::lock_guard<std::recursive_mutex> guard(getFrameMutex);
 
    ZmqLogger::Instance()->AppendDebugMethod(
        "Timeline::update_open_clips (before)",
        "does_clip_intersect", does_clip_intersect,
        "closing_clips.size()", closing_clips.size(),
        "open_clips.size()", open_clips.size());
 
    // is clip already in list?
    bool clip_found = open_clips.count(clip);
 
    // The registry, Clip, and nested Reader can become inconsistent after a
    // transient reader close. Trust the actual objects over open_clips and run
    // them through a clean Close/Open cycle while this clip still intersects.
    // Otherwise FrameMapper converts ReaderClosed into a black frame which can
    // be repeatedly cached on every still-intersecting timing update.
    if (clip_found && does_clip_intersect)
    {
        bool clip_reader_open = false;
        try {
            clip_reader_open = clip->Reader() && clip->Reader()->IsOpen();
        } catch (const ReaderClosed & e) {
            // A missing/replaced reader is equivalent to a closed reader here.
            clip_reader_open = false;
        }
        if (!clip->IsOpen() || !clip_reader_open)
        {
            open_clips.erase(clip);
            clip->Close();
            clip_found = false;
        }
    }
 
    if (clip_found && !does_clip_intersect)
    {
        // Remove clip from 'opened' list, because it's closed now
        open_clips.erase(clip);
 
        // Close clip
        clip->Close();
    }
    else if (!clip_found && does_clip_intersect)
    {
        try {
            // Open the clip
            clip->Open();
            // Add clip to 'opened' list only after a successful open.
            open_clips[clip] = clip;
 
        } catch (const InvalidFile & e) {
            // ...
        }
    }
 
    // Debug output
    ZmqLogger::Instance()->AppendDebugMethod(
        "Timeline::update_open_clips (after)",
        "does_clip_intersect", does_clip_intersect,
        "clip_found", clip_found,
        "closing_clips.size()", closing_clips.size(),
        "open_clips.size()", open_clips.size());
}
 
// Calculate the max and min duration (in seconds) of the timeline, based on all the clips, and cache the value
void Timeline::calculate_max_duration() {
    double last_clip = 0.0;
    double last_effect = 0.0;
    double first_clip = std::numeric_limits<double>::max();
    double first_effect = std::numeric_limits<double>::max();
 
    // Find the last and first clip
    if (!clips.empty()) {
        // Find the clip with the maximum end frame
        const auto max_clip = std::max_element(
            clips.begin(), clips.end(), CompareClipEndFrames());
        last_clip = (*max_clip)->Position() + (*max_clip)->Duration();
 
        // Find the clip with the minimum start position (ignoring layer)
        const auto min_clip = std::min_element(
            clips.begin(), clips.end(), [](const openshot::Clip* lhs, const openshot::Clip* rhs) {
                return lhs->Position() < rhs->Position();
            });
        first_clip = (*min_clip)->Position();
    }
 
    // Find the last and first effect
    if (!effects.empty()) {
        // Find the effect with the maximum end frame
        const auto max_effect = std::max_element(
            effects.begin(), effects.end(), CompareEffectEndFrames());
        last_effect = (*max_effect)->Position() + (*max_effect)->Duration();
 
        // Find the effect with the minimum start position
        const auto min_effect = std::min_element(
            effects.begin(), effects.end(), [](const openshot::EffectBase* lhs, const openshot::EffectBase* rhs) {
                return lhs->Position() < rhs->Position();
            });
        first_effect = (*min_effect)->Position();
    }
 
    // Calculate the max and min time
    max_time = std::max(last_clip, last_effect);
    min_time = std::min(first_clip, first_effect);
 
    // If no clips or effects exist, set min_time to 0
    if (clips.empty() && effects.empty()) {
        min_time = 0.0;
        max_time = 0.0;
    }
}
 
// Sort clips by position on the timeline
void Timeline::sort_clips()
{
    // Get lock (prevent getting frames while this happens)
    const std::lock_guard<std::recursive_mutex> guard(getFrameMutex);
 
    // Debug output
    ZmqLogger::Instance()->AppendDebugMethod(
        "Timeline::SortClips",
        "clips.size()", clips.size());
 
    // sort clips
    clips.sort(CompareClips());
 
    // calculate max timeline duration
    calculate_max_duration();
}
 
// Sort effects by position on the timeline
void Timeline::sort_effects()
{
    // Get lock (prevent getting frames while this happens)
    const std::lock_guard<std::recursive_mutex> guard(getFrameMutex);
 
    // sort clips
    effects.sort(CompareEffects());
 
    // calculate max timeline duration
    calculate_max_duration();
}
 
// Clear all clips from timeline
void Timeline::Clear()
{
    ZmqLogger::Instance()->AppendDebugMethod("Timeline::Clear");
 
    // Get lock (prevent getting frames while this happens)
    const std::lock_guard<std::recursive_mutex> guard(getFrameMutex);
 
    // Close all open clips
    for (auto clip : clips)
    {
        update_open_clips(clip, false);
 
        // Delete clip object (if timeline allocated it)
        bool allocated = allocated_clips.count(clip);
        if (allocated) {
            delete clip;
        }
    }
    // Clear all clips
    clips.clear();
    allocated_clips.clear();
 
    // Close all effects
    for (auto effect : effects)
    {
        // Delete effect object (if timeline allocated it)
        bool allocated = allocated_effects.count(effect);
        if (allocated) {
            delete effect;
        }
    }
    // Clear all effects
    effects.clear();
    allocated_effects.clear();
 
    // Delete all FrameMappers
    for (auto mapper : allocated_frame_mappers)
    {
        mapper->Reader(NULL);
        mapper->Close();
        delete mapper;
    }
    allocated_frame_mappers.clear();
}
 
// Close the reader (and any resources it was consuming)
void Timeline::Close()
{
    ZmqLogger::Instance()->AppendDebugMethod("Timeline::Close");
 
    // Get lock (prevent getting frames while this happens)
    const std::lock_guard<std::recursive_mutex> guard(getFrameMutex);
 
    // Close all open clips
    for (auto clip : clips)
    {
        // Open or Close this clip, based on if it's intersecting or not
        update_open_clips(clip, false);
    }
 
    // Mark timeline as closed
    is_open = false;
 
    // Clear all cache (deep clear, including nested Readers)
    ClearAllCache(true);
}
 
// Open the reader (and start consuming resources)
void Timeline::Open()
{
    is_open = true;
}
 
// Compare 2 floating point numbers for equality
bool Timeline::isEqual(double a, double b)
{
    return fabs(a - b) < 0.000001;
}
 
// Get an openshot::Frame object for a specific frame number of this reader.
std::shared_ptr<Frame> Timeline::GetFrame(int64_t requested_frame)
{
    // Adjust out of bounds frame number
    if (requested_frame < 1)
        requested_frame = 1;
    const int64_t max_frame = GetMaxFrame();
    const bool past_timeline_end = (max_frame > 0 && requested_frame > max_frame);
 
    // Check cache
    std::shared_ptr<Frame> frame;
    if (!past_timeline_end)
        frame = final_cache->GetFrame(requested_frame);
    if (frame) {
        // Debug output
        ZmqLogger::Instance()->AppendDebugMethod(
            "Timeline::GetFrame (Cached frame found)",
            "requested_frame", requested_frame);
 
        // Return cached frame
        return frame;
    }
    else
    {
        // Prevent async calls to the following code
        const std::lock_guard<std::recursive_mutex> lock(getFrameMutex);
 
        // Check cache 2nd time
        std::shared_ptr<Frame> frame;
        if (!past_timeline_end)
            frame = final_cache->GetFrame(requested_frame);
        if (frame) {
            // Debug output
            ZmqLogger::Instance()->AppendDebugMethod(
                    "Timeline::GetFrame (Cached frame found on 2nd check)",
                    "requested_frame", requested_frame);
 
            // Return cached frame
            return frame;
        } else {
            // Get a list of clips that intersect with the requested section of timeline
            // This also opens the readers for intersecting clips, and marks non-intersecting clips as 'needs closing'
            std::vector<Clip *> nearby_clips;
            nearby_clips = find_intersecting_clips(requested_frame, 1, true);
 
            // Debug output
            ZmqLogger::Instance()->AppendDebugMethod(
                    "Timeline::GetFrame (processing frame)",
                    "requested_frame", requested_frame,
                    "omp_get_thread_num()", omp_get_thread_num());
 
            // Init some basic properties about this frame
            int samples_in_frame = Frame::GetSamplesPerFrame(requested_frame, info.fps, info.sample_rate, info.channels);
 
            // Create blank frame (which will become the requested frame)
            std::shared_ptr<Frame> new_frame(std::make_shared<Frame>(requested_frame, preview_width, preview_height, "#000000", samples_in_frame, info.channels));
            new_frame->AddAudioSilence(samples_in_frame);
            new_frame->SampleRate(info.sample_rate);
            new_frame->ChannelsLayout(info.channel_layout);
 
            // Debug output
            ZmqLogger::Instance()->AppendDebugMethod(
                    "Timeline::GetFrame (Adding solid color)",
                    "requested_frame", requested_frame,
                    "info.width", info.width,
                    "info.height", info.height);
 
            // Add Background Color to 1st layer (if animated or not black)
            if ((color.red.GetCount() > 1 || color.green.GetCount() > 1 || color.blue.GetCount() > 1) ||
                (color.red.GetValue(requested_frame) != 0.0 || color.green.GetValue(requested_frame) != 0.0 ||
                 color.blue.GetValue(requested_frame) != 0.0))
                new_frame->AddColor(preview_width, preview_height, color.GetColorHex(requested_frame));
 
            // Debug output
            ZmqLogger::Instance()->AppendDebugMethod(
                    "Timeline::GetFrame (Loop through clips)",
                    "requested_frame", requested_frame,
                    "clips.size()", clips.size(),
                    "nearby_clips.size()", nearby_clips.size());
 
            // Precompute per-clip timing for this requested frame
            struct ClipInfo {
                Clip* clip;
                int64_t start_pos;
                int64_t end_pos;
                int64_t start_frame;
                int64_t frame_number;
                bool intersects;
            };
            std::vector<ClipInfo> clip_infos;
            clip_infos.reserve(nearby_clips.size());
            const double fpsD = info.fps.ToDouble();
 
            for (auto clip : nearby_clips) {
                int64_t start_pos  = static_cast<int64_t>(std::llround(clip->Position() * fpsD)) + 1;
                int64_t end_pos    = static_cast<int64_t>(std::llround((clip->Position() + clip->Duration()) * fpsD));
                bool intersects    = (start_pos <= requested_frame && end_pos >= requested_frame);
                int64_t start_frame = static_cast<int64_t>(std::llround(clip->Start() * fpsD)) + 1;
                int64_t frame_number = requested_frame - start_pos + start_frame;
                clip_infos.push_back({clip, start_pos, end_pos, start_frame, frame_number, intersects});
            }
 
            // Determine top clip per layer (linear, no nested loop)
            std::unordered_map<int, int64_t> top_start_for_layer;
            std::unordered_map<int, Clip*> top_clip_for_layer;
            for (const auto& ci : clip_infos) {
                if (!ci.intersects) continue;
                const int layer = ci.clip->Layer();
                auto it = top_start_for_layer.find(layer);
                if (it == top_start_for_layer.end() || ci.start_pos > it->second) {
                    top_start_for_layer[layer] = ci.start_pos;   // strictly greater to match prior logic
                    top_clip_for_layer[layer]  = ci.clip;
                }
            }
 
            // Compute max_volume across all overlapping clips once
            float max_volume_sum = 0.0f;
            for (const auto& ci : clip_infos) {
                if (!ci.intersects) continue;
                if (ci.clip->Reader() && ci.clip->Reader()->info.has_audio &&
                    ci.clip->has_audio.GetInt(ci.frame_number) != 0) {
                    max_volume_sum += static_cast<float>(ci.clip->volume.GetValue(ci.frame_number));
                }
            }
 
            // Compose intersecting clips in a single pass
            for (const auto& ci : clip_infos) {
                // Debug output
                ZmqLogger::Instance()->AppendDebugMethod(
                        "Timeline::GetFrame (Does clip intersect)",
                        "requested_frame", requested_frame,
                        "clip->Position()", ci.clip->Position(),
                        "clip->Duration()", ci.clip->Duration(),
                        "does_clip_intersect", ci.intersects);
 
                // Clip is visible
                if (ci.intersects) {
                    // Is this the top clip on its layer?
                    bool is_top_clip = false;
                    const int layer = ci.clip->Layer();
                    auto top_it = top_clip_for_layer.find(layer);
                    if (top_it != top_clip_for_layer.end())
                        is_top_clip = (top_it->second == ci.clip);
 
                    // Determine the frame needed for this clip (based on the position on the timeline)
                    int64_t clip_frame_number = ci.frame_number;
 
                    // Debug output
                    ZmqLogger::Instance()->AppendDebugMethod(
                            "Timeline::GetFrame (Calculate clip's frame #)",
                            "clip->Position()", ci.clip->Position(),
                            "clip->Start()", ci.clip->Start(),
                            "info.fps.ToFloat()", info.fps.ToFloat(),
                            "clip_frame_number", clip_frame_number);
 
                    // Add clip's frame as layer
                    add_layer(new_frame, ci.clip, clip_frame_number, is_top_clip, max_volume_sum);
 
                } else {
                    // Debug output
                    ZmqLogger::Instance()->AppendDebugMethod(
                            "Timeline::GetFrame (clip does not intersect)",
                            "requested_frame", requested_frame,
                            "does_clip_intersect", ci.intersects);
                }
 
            } // end clip loop
 
            // Debug output
            ZmqLogger::Instance()->AppendDebugMethod(
                    "Timeline::GetFrame (Add frame to cache)",
                    "requested_frame", requested_frame,
                    "info.width", info.width,
                    "info.height", info.height);
 
            // Set frame # on mapped frame
            new_frame->SetFrameNumber(requested_frame);
 
                // Add final frame to cache (only for valid timeline range)
                if (!past_timeline_end)
                    final_cache->Add(new_frame);
            // Return frame (or blank frame)
            return new_frame;
        }
    }
}
 
 
// Find intersecting clips (or non intersecting clips)
std::vector<Clip*> Timeline::find_intersecting_clips(int64_t requested_frame, int number_of_frames, bool include)
{
    // Find matching clips
    std::vector<Clip*> matching_clips;
 
    // Calculate time of frame
    const int64_t min_requested_frame = requested_frame;
    const int64_t max_requested_frame = requested_frame + (number_of_frames - 1);
 
    // Find Clips at this time
    matching_clips.reserve(clips.size());
    const double fpsD = info.fps.ToDouble();
    for (auto clip : clips)
    {
        // Does clip intersect the current requested time
        int64_t clip_start_position = static_cast<int64_t>(std::llround(clip->Position() * fpsD)) + 1;
        int64_t clip_end_position   = static_cast<int64_t>(std::llround((clip->Position() + clip->Duration()) * fpsD)) + 1;
 
        bool does_clip_intersect =
                (clip_start_position <= min_requested_frame || clip_start_position <= max_requested_frame) &&
                (clip_end_position >= min_requested_frame || clip_end_position >= max_requested_frame);
 
        // Debug output
        ZmqLogger::Instance()->AppendDebugMethod(
            "Timeline::find_intersecting_clips (Is clip near or intersecting)",
            "requested_frame", requested_frame,
            "min_requested_frame", min_requested_frame,
            "max_requested_frame", max_requested_frame,
            "clip->Position()", clip->Position(),
            "does_clip_intersect", does_clip_intersect);
 
        // Open (or schedule for closing) this clip, based on if it's intersecting or not
        update_open_clips(clip, does_clip_intersect);
 
        // Clip is visible
        if (does_clip_intersect && include)
            // Add the intersecting clip
            matching_clips.push_back(clip);
 
        else if (!does_clip_intersect && !include)
            // Add the non-intersecting clip
            matching_clips.push_back(clip);
 
    } // end clip loop
 
    // return list
    return matching_clips;
}
 
// Set the cache object used by this reader
void Timeline::SetCache(CacheBase* new_cache) {
    // Get lock (prevent getting frames while this happens)
    const std::lock_guard<std::recursive_mutex> lock(getFrameMutex);
 
    // Destroy previous cache (if managed by timeline)
    if (managed_cache && final_cache) {
        delete final_cache;
        final_cache = NULL;
        managed_cache = false;
    }
 
    // Set new cache
    final_cache = new_cache;
}
 
// Generate JSON string of this object
std::string Timeline::Json() const {
 
    // Return formatted string
    return JsonValue().toStyledString();
}
 
// Generate Json::Value for this object
Json::Value Timeline::JsonValue() const {
 
    // Create root json object
    Json::Value root = ReaderBase::JsonValue(); // get parent properties
    root["type"] = "Timeline";
    root["viewport_scale"] = viewport_scale.JsonValue();
    root["viewport_x"] = viewport_x.JsonValue();
    root["viewport_y"] = viewport_y.JsonValue();
    root["color"] = color.JsonValue();
    root["path"] = path;
 
    // Add array of clips
    root["clips"] = Json::Value(Json::arrayValue);
 
    // Find Clips at this time
    for (const auto existing_clip : clips)
    {
        root["clips"].append(existing_clip->JsonValue());
    }
 
    // Add array of effects
    root["effects"] = Json::Value(Json::arrayValue);
 
    // loop through effects
    for (const auto existing_effect: effects)
    {
        root["effects"].append(existing_effect->JsonValue());
    }
 
    // return JsonValue
    return root;
}
 
// Load JSON string into this object
void Timeline::SetJson(const std::string value) {
 
    // Get lock (prevent getting frames while this happens)
    const std::lock_guard<std::recursive_mutex> lock(getFrameMutex);
 
    // 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 Timeline::SetJsonValue(const Json::Value root) {
 
    // Get lock (prevent getting frames while this happens)
    const std::lock_guard<std::recursive_mutex> lock(getFrameMutex);
 
    // Close timeline before we do anything (this closes all clips)
    bool was_open = is_open;
    Close();
 
    // Set parent data
    ReaderBase::SetJsonValue(root);
 
    // Set data from Json (if key is found)
    if (!root["path"].isNull())
        path = root["path"].asString();
 
    if (!root["clips"].isNull()) {
        // Clear existing clips
        clips.clear();
 
        // loop through clips
        for (const Json::Value existing_clip : root["clips"]) {
            // Skip NULL nodes
            if (existing_clip.isNull()) {
                continue;
            }
 
            // Create Clip
            Clip *c = new Clip();
 
            // Keep track of allocated clip objects
            allocated_clips.insert(c);
 
            // When a clip is attached to an object, it searches for the object
            // on it's parent timeline. Setting the parent timeline of the clip here
            // allows attaching it to an object when exporting the project (because)
            // the exporter script initializes the clip and it's effects
            // before setting its parent timeline.
            c->ParentTimeline(this);
 
            // Load Json into Clip
            c->SetJsonValue(existing_clip);
 
            // Add Clip to Timeline
            AddClip(c);
        }
    }
 
    if (!root["effects"].isNull()) {
        // Clear existing effects
        effects.clear();
 
        // loop through effects
        for (const Json::Value existing_effect :root["effects"]) {
            // Skip NULL nodes
            if (existing_effect.isNull()) {
                continue;
            }
 
            // Create Effect
            EffectBase *e = NULL;
 
            if (!existing_effect["type"].isNull()) {
                // Create instance of effect
                if ( (e = EffectInfo().CreateEffect(existing_effect["type"].asString())) ) {
 
                    // Keep track of allocated effect objects
                    allocated_effects.insert(e);
 
                    // Load Json into Effect
                    e->SetJsonValue(existing_effect);
 
                    // Add Effect to Timeline
                    AddEffect(e);
                }
            }
        }
    }
 
    if (!root["duration"].isNull()) {
        // Update duration of timeline
        info.duration = root["duration"].asDouble();
        info.video_length = info.fps.ToFloat() * info.duration;
    }
 
    // Update preview settings
    preview_width = info.width;
    preview_height = info.height;
 
    // Resort (and recalculate min/max duration)
    sort_clips();
    sort_effects();
 
    // Re-open if needed
    if (was_open)
        Open();
 
    // Timeline content changed: notify cache clients to rescan active window.
    BumpCacheEpoch();
}
 
// Apply a special formatted JSON object, which represents a change to the timeline (insert, update, delete)
void Timeline::ApplyJsonDiff(std::string value) {
 
    // Get lock (prevent getting frames while this happens)
    const std::lock_guard<std::recursive_mutex> lock(getFrameMutex);
 
    // Parse JSON string into JSON objects
    try
    {
        const Json::Value root = openshot::stringToJson(value);
        const uint64_t initial_cache_epoch = CacheEpoch();
        // Process the JSON change array, loop through each item
        for (const Json::Value change : root) {
            std::string change_key = change["key"][(uint)0].asString();
 
            // Process each type of change
            if (change_key == "clips")
                // Apply to CLIPS
                apply_json_to_clips(change);
 
            else if (change_key == "effects")
                // Apply to EFFECTS
                apply_json_to_effects(change);
 
            else
                // Apply to TIMELINE
                apply_json_to_timeline(change);
 
        }
 
        // Timeline content changed: notify cache clients to rescan active window.
        if (!root.empty() && CacheEpoch() == initial_cache_epoch) {
            BumpCacheEpoch();
        }
    }
    catch (const std::exception& e)
    {
        // Error parsing JSON (or missing keys)
        throw InvalidJSON("JSON is invalid (missing keys or invalid data types)");
    }
}
 
void Timeline::BumpCacheEpoch() {
    cache_epoch.fetch_add(1, std::memory_order_relaxed);
}
 
void Timeline::InvalidateCacheForClip(const Clip* clip) {
    if (!clip || !final_cache) {
        return;
    }
 
    const double fpsD = info.fps.ToDouble();
    const int64_t starting_frame = static_cast<int64_t>(std::llround(clip->Position() * fpsD)) + 1;
    const int64_t ending_frame = static_cast<int64_t>(std::llround((clip->Position() + clip->Duration()) * fpsD)) + 1;
    final_cache->Remove(starting_frame - 8, ending_frame + 8);
    BumpCacheEpoch();
}
 
// Apply JSON diff to clips
void Timeline::apply_json_to_clips(Json::Value change) {
 
    // Get key and type of change
    std::string change_type = change["type"].asString();
    std::string clip_id = "";
    Clip *existing_clip = NULL;
 
    // Find id of clip (if any)
    for (auto key_part : change["key"]) {
        // Get each change
        if (key_part.isObject()) {
            // Check for id
            if (!key_part["id"].isNull()) {
                // Set the id
                clip_id = key_part["id"].asString();
 
                // Find matching clip in timeline (if any)
                for (auto c : clips)
                {
                    if (c->Id() == clip_id) {
                        existing_clip = c;
                        break; // clip found, exit loop
                    }
                }
                break; // id found, exit loop
            }
        }
    }
 
    // Check for a more specific key (targetting this clip's effects)
    // For example: ["clips", {"id:123}, "effects", {"id":432}]
    if (existing_clip && change["key"].size() == 4 && change["key"][2] == "effects")
    {
        // This change is actually targetting a specific effect under a clip (and not the clip)
        Json::Value key_part = change["key"][3];
 
        if (key_part.isObject()) {
            // Check for id
            if (!key_part["id"].isNull())
            {
                // Set the id
                std::string effect_id = key_part["id"].asString();
 
                // Find matching effect in timeline (if any)
                std::list<EffectBase*> effect_list = existing_clip->Effects();
                for (auto e : effect_list)
                {
                    if (e->Id() == effect_id) {
                        // Apply the change to the effect directly
                        apply_json_to_effects(change, e);
 
                        // Effect-only diffs must clear the owning clip cache.
                        if (existing_clip->GetCache()) {
                            existing_clip->GetCache()->Clear();
                        }
 
                        // Calculate start and end frames that this impacts, and remove those frames from the cache
                        int64_t new_starting_frame = (existing_clip->Position() * info.fps.ToDouble()) + 1;
                        int64_t new_ending_frame = ((existing_clip->Position() + existing_clip->Duration()) * info.fps.ToDouble()) + 1;
                        final_cache->Remove(new_starting_frame - 8, new_ending_frame + 8);
 
                        return; // effect found, don't update clip
                    }
                }
            }
        }
    }
 
    // Determine type of change operation
    if (change_type == "insert") {
 
        // Create clip
        Clip *clip = new Clip();
 
        // Keep track of allocated clip objects
        allocated_clips.insert(clip);
 
        // Match full timeline JSON loading: parent timeline must be available
        // before clip JSON can inflate nested readers/effects.
        clip->ParentTimeline(this);
 
        // Set properties of clip from JSON
        clip->SetJsonValue(change["value"]);
 
        // Add clip to timeline
        AddClip(clip);
 
    } else if (change_type == "update") {
 
        // Update existing clip
        if (existing_clip) {
            // Calculate start and end frames prior to the update
            int64_t old_starting_frame = (existing_clip->Position() * info.fps.ToDouble()) + 1;
            int64_t old_ending_frame = ((existing_clip->Position() + existing_clip->Duration()) * info.fps.ToDouble()) + 1;
 
            // Update clip properties from JSON
            existing_clip->SetJsonValue(change["value"]);
 
            // Calculate new start and end frames after the update
            int64_t new_starting_frame = (existing_clip->Position() * info.fps.ToDouble()) + 1;
            int64_t new_ending_frame = ((existing_clip->Position() + existing_clip->Duration()) * info.fps.ToDouble()) + 1;
 
            // Remove both the old and new ranges from the timeline cache
            final_cache->Remove(old_starting_frame - 8, old_ending_frame + 8);
            final_cache->Remove(new_starting_frame - 8, new_ending_frame + 8);
 
            // Apply framemapper (or update existing framemapper)
            if (auto_map_clips) {
                apply_mapper_to_clip(existing_clip);
            }
        }
 
    } else if (change_type == "delete") {
 
        // Remove existing clip
        if (existing_clip) {
            // Remove clip from timeline
            RemoveClip(existing_clip);
 
            // Calculate start and end frames that this impacts, and remove those frames from the cache
            int64_t old_starting_frame = (existing_clip->Position() * info.fps.ToDouble()) + 1;
            int64_t old_ending_frame = ((existing_clip->Position() + existing_clip->Duration()) * info.fps.ToDouble()) + 1;
            final_cache->Remove(old_starting_frame - 8, old_ending_frame + 8);
        }
 
    }
 
    // Re-Sort Clips (since they likely changed)
    sort_clips();
}
 
// Apply JSON diff to effects
void Timeline::apply_json_to_effects(Json::Value change) {
 
    // Get key and type of change
    std::string change_type = change["type"].asString();
    EffectBase *existing_effect = NULL;
 
    // Find id of an effect (if any)
    for (auto key_part : change["key"]) {
 
        if (key_part.isObject()) {
            // Check for id
            if (!key_part["id"].isNull())
            {
                // Set the id
                std::string effect_id = key_part["id"].asString();
 
                // Find matching effect in timeline (if any)
                for (auto e : effects)
                {
                    if (e->Id() == effect_id) {
                        existing_effect = e;
                        break; // effect found, exit loop
                    }
                }
                break; // id found, exit loop
            }
        }
    }
 
    // Now that we found the effect, apply the change to it
    if (existing_effect || change_type == "insert") {
        // Apply change to effect
        apply_json_to_effects(change, existing_effect);
    }
}
 
// Apply JSON diff to effects (if you already know which effect needs to be updated)
void Timeline::apply_json_to_effects(Json::Value change, EffectBase* existing_effect) {
 
    // Get key and type of change
    std::string change_type = change["type"].asString();
 
    // Calculate start and end frames that this impacts, and remove those frames from the cache
    if (!change["value"].isArray() && !change["value"]["position"].isNull()) {
        int64_t new_starting_frame = (change["value"]["position"].asDouble() * info.fps.ToDouble()) + 1;
        int64_t new_ending_frame = ((change["value"]["position"].asDouble() + change["value"]["end"].asDouble() - change["value"]["start"].asDouble()) * info.fps.ToDouble()) + 1;
        final_cache->Remove(new_starting_frame - 8, new_ending_frame + 8);
    }
 
    // Determine type of change operation
    if (change_type == "insert") {
 
        // Determine type of effect
        std::string effect_type = change["value"]["type"].asString();
 
        // Create Effect
        EffectBase *e = NULL;
 
        // Init the matching effect object
        if ( (e = EffectInfo().CreateEffect(effect_type)) ) {
 
            // Keep track of allocated effect objects
            allocated_effects.insert(e);
 
            // Load Json into Effect
            e->SetJsonValue(change["value"]);
 
            // Add Effect to Timeline
            AddEffect(e);
        }
 
    } else if (change_type == "update") {
 
        // Update existing effect
        if (existing_effect) {
 
            // Calculate start and end frames that this impacts, and remove those frames from the cache
            int64_t old_starting_frame = (existing_effect->Position() * info.fps.ToDouble()) + 1;
            int64_t old_ending_frame = ((existing_effect->Position() + existing_effect->Duration()) * info.fps.ToDouble()) + 1;
            final_cache->Remove(old_starting_frame - 8, old_ending_frame + 8);
 
            // Update effect properties from JSON
            existing_effect->SetJsonValue(change["value"]);
        }
 
    } else if (change_type == "delete") {
 
        // Remove existing effect
        if (existing_effect) {
 
            // Calculate start and end frames that this impacts, and remove those frames from the cache
            int64_t old_starting_frame = (existing_effect->Position() * info.fps.ToDouble()) + 1;
            int64_t old_ending_frame = ((existing_effect->Position() + existing_effect->Duration()) * info.fps.ToDouble()) + 1;
            final_cache->Remove(old_starting_frame - 8, old_ending_frame + 8);
 
            // Remove effect from timeline
            RemoveEffect(existing_effect);
        }
 
    }
 
    // Re-Sort Effects (since they likely changed)
    sort_effects();
}
 
// Apply JSON diff to timeline properties
void Timeline::apply_json_to_timeline(Json::Value change) {
    bool cache_dirty = true;
 
    // Get key and type of change
    std::string change_type = change["type"].asString();
    std::string root_key = change["key"][(uint)0].asString();
    std::string sub_key = "";
    if (change["key"].size() >= 2)
        sub_key = change["key"][(uint)1].asString();
 
    // Determine type of change operation
    if (change_type == "insert" || change_type == "update") {
 
        // INSERT / UPDATE
        // Check for valid property
        if (root_key == "color")
            // Set color
            color.SetJsonValue(change["value"]);
        else if (root_key == "viewport_scale")
            // Set viewport scale
            viewport_scale.SetJsonValue(change["value"]);
        else if (root_key == "viewport_x")
            // Set viewport x offset
            viewport_x.SetJsonValue(change["value"]);
        else if (root_key == "viewport_y")
            // Set viewport y offset
            viewport_y.SetJsonValue(change["value"]);
        else if (root_key == "duration") {
            // Update duration of timeline
            info.duration = change["value"].asDouble();
            info.video_length = info.fps.ToFloat() * info.duration;
 
            // We don't want to clear cache for duration adjustments
            cache_dirty = false;
        }
        else if (root_key == "width") {
            // Set width
            info.width = change["value"].asInt();
            preview_width = info.width;
        }
        else if (root_key == "height") {
            // Set height
            info.height = change["value"].asInt();
            preview_height = info.height;
        }
        else if (root_key == "fps" && sub_key == "" && change["value"].isObject()) {
            // Set fps fraction
            if (!change["value"]["num"].isNull())
                info.fps.num = change["value"]["num"].asInt();
            if (!change["value"]["den"].isNull())
                info.fps.den = change["value"]["den"].asInt();
        }
        else if (root_key == "fps" && sub_key == "num")
            // Set fps.num
            info.fps.num = change["value"].asInt();
        else if (root_key == "fps" && sub_key == "den")
            // Set fps.den
            info.fps.den = change["value"].asInt();
        else if (root_key == "display_ratio" && sub_key == "" && change["value"].isObject()) {
            // Set display_ratio fraction
            if (!change["value"]["num"].isNull())
                info.display_ratio.num = change["value"]["num"].asInt();
            if (!change["value"]["den"].isNull())
                info.display_ratio.den = change["value"]["den"].asInt();
        }
        else if (root_key == "display_ratio" && sub_key == "num")
            // Set display_ratio.num
            info.display_ratio.num = change["value"].asInt();
        else if (root_key == "display_ratio" && sub_key == "den")
            // Set display_ratio.den
            info.display_ratio.den = change["value"].asInt();
        else if (root_key == "pixel_ratio" && sub_key == "" && change["value"].isObject()) {
            // Set pixel_ratio fraction
            if (!change["value"]["num"].isNull())
                info.pixel_ratio.num = change["value"]["num"].asInt();
            if (!change["value"]["den"].isNull())
                info.pixel_ratio.den = change["value"]["den"].asInt();
        }
        else if (root_key == "pixel_ratio" && sub_key == "num")
            // Set pixel_ratio.num
            info.pixel_ratio.num = change["value"].asInt();
        else if (root_key == "pixel_ratio" && sub_key == "den")
            // Set pixel_ratio.den
            info.pixel_ratio.den = change["value"].asInt();
 
        else if (root_key == "sample_rate")
            // Set sample rate
            info.sample_rate = change["value"].asInt();
        else if (root_key == "channels")
            // Set channels
            info.channels = change["value"].asInt();
        else if (root_key == "channel_layout")
            // Set channel layout
            info.channel_layout = (ChannelLayout) change["value"].asInt();
        else
            // Error parsing JSON (or missing keys)
            throw InvalidJSONKey("JSON change key is invalid", change.toStyledString());
 
 
    } else if (change["type"].asString() == "delete") {
 
        // DELETE / RESET
        // Reset the following properties (since we can't delete them)
        if (root_key == "color") {
            color = Color();
            color.red = Keyframe(0.0);
            color.green = Keyframe(0.0);
            color.blue = Keyframe(0.0);
        }
        else if (root_key == "viewport_scale")
            viewport_scale = Keyframe(1.0);
        else if (root_key == "viewport_x")
            viewport_x = Keyframe(0.0);
        else if (root_key == "viewport_y")
            viewport_y = Keyframe(0.0);
        else
            // Error parsing JSON (or missing keys)
            throw InvalidJSONKey("JSON change key is invalid", change.toStyledString());
 
    }
 
    if (cache_dirty) {
        // Clear entire cache
        ClearAllCache();
    }
}
 
// Clear all caches
void Timeline::ClearAllCache(bool deep) {
    // Get lock (prevent getting frames while this happens)
    const std::lock_guard<std::recursive_mutex> guard(getFrameMutex);
 
    // Clear primary cache
    if (final_cache) {
        final_cache->Clear();
    }
 
    // Loop through all clips
    try {
        for (const auto clip : clips) {
            // Clear cache on clip and reader if present
            if (clip->Reader()) {
                if (auto rc = clip->Reader()->GetCache())
                    rc->Clear();
 
                // Clear nested Reader (if deep clear requested)
                if (deep && clip->Reader()->Name() == "FrameMapper") {
                    FrameMapper *nested_reader = static_cast<FrameMapper *>(clip->Reader());
                    if (nested_reader->Reader()) {
                        if (auto nc = nested_reader->Reader()->GetCache())
                            nc->Clear();
                    }
                }
            }
 
            // Clear clip cache
            if (auto cc = clip->GetCache())
                cc->Clear();
        }
    } catch (const ReaderClosed & e) {
        // ...
    }
 
    // Cache content changed: notify cache clients to rebuild their window baseline.
    BumpCacheEpoch();
}
 
// Set Max Image Size (used for performance optimization). Convenience function for setting
// Settings::Instance()->MAX_WIDTH and Settings::Instance()->MAX_HEIGHT.
void Timeline::SetMaxSize(int width, int height) {
    // Maintain aspect ratio regardless of what size is passed in
    QSize display_ratio_size = QSize(info.width, info.height);
    QSize proposed_size = QSize(std::min(width, info.width), std::min(height, info.height));
 
    // Scale QSize up to proposed size
    display_ratio_size.scale(proposed_size, Qt::KeepAspectRatio);
 
    // Update preview settings
    preview_width = display_ratio_size.width();
    preview_height = display_ratio_size.height();
}
 
// Resolve equal-power audio gains from transition placement relative to the clip edges.
std::pair<float, float> Timeline::ResolveTransitionAudioGains(Clip* source_clip, int64_t timeline_frame_number, bool is_top_clip) const
{
    constexpr double half_pi = 1.57079632679489661923;
 
    if (!source_clip)
        return {1.0f, 1.0f};
 
    const double fpsD = info.fps.ToDouble();
    Mask* active_mask = nullptr;
    int64_t effect_start_position = 0;
    int64_t effect_end_position = 0;
 
    // Find the single active transition on this layer that requested overlapping audio fades.
    for (auto effect : effects) {
        if (effect->Layer() != source_clip->Layer())
            continue;
 
        auto* mask = dynamic_cast<Mask*>(effect);
        if (!mask || !mask->fade_audio_hint)
            continue;
 
        const int64_t start_pos = static_cast<int64_t>(std::llround(effect->Position() * fpsD)) + 1;
        const int64_t end_pos = static_cast<int64_t>(std::llround((effect->Position() + effect->Duration()) * fpsD));
        if (start_pos > timeline_frame_number || end_pos < timeline_frame_number)
            continue;
 
        if (active_mask)
            return {1.0f, 1.0f};
 
        active_mask = mask;
        effect_start_position = start_pos;
        effect_end_position = end_pos;
    }
 
    if (!active_mask)
        return {1.0f, 1.0f};
 
    struct AudibleClipInfo {
        Clip* clip;
        int64_t start_pos;
        int64_t end_pos;
    };
 
    std::vector<AudibleClipInfo> audible_clips;
    audible_clips.reserve(2);
 
    // Collect the audible clips covered by this transition on the current layer.
    for (auto clip : clips) {
        if (clip->Layer() != source_clip->Layer())
            continue;
        if (!clip->Reader() || !clip->Reader()->info.has_audio)
            continue;
 
        const int64_t clip_start_pos = static_cast<int64_t>(std::llround(clip->Position() * fpsD)) + 1;
        const int64_t clip_end_pos = static_cast<int64_t>(std::llround((clip->Position() + clip->Duration()) * fpsD));
        if (clip_start_pos > timeline_frame_number || clip_end_pos < timeline_frame_number)
            continue;
 
        const int64_t clip_start_frame = static_cast<int64_t>(std::llround(clip->Start() * fpsD)) + 1;
        const int64_t clip_frame_number = timeline_frame_number - clip_start_pos + clip_start_frame;
        if (clip->has_audio.GetInt(clip_frame_number) == 0)
            continue;
 
        audible_clips.push_back({clip, clip_start_pos, clip_end_pos});
        if (audible_clips.size() > 2)
            return {1.0f, 1.0f};
    }
 
    if (audible_clips.empty())
        return {1.0f, 1.0f};
 
    // Skip clips that are not actually participating in this transition audio decision.
    const auto source_it = std::find_if(
        audible_clips.begin(),
        audible_clips.end(),
        [source_clip](const AudibleClipInfo& info) {
            return info.clip == source_clip;
        });
    if (source_it == audible_clips.end())
        return {1.0f, 1.0f};
 
    // Keep the current top/non-top clip routing intact when two clips overlap.
    if (audible_clips.size() == 2) {
        auto top_it = std::max_element(
            audible_clips.begin(),
            audible_clips.end(),
            [](const AudibleClipInfo& lhs, const AudibleClipInfo& rhs) {
                if (lhs.start_pos != rhs.start_pos)
                    return lhs.start_pos < rhs.start_pos;
                return std::less<Clip*>()(lhs.clip, rhs.clip);
            });
        if ((is_top_clip && source_clip != top_it->clip) || (!is_top_clip && source_clip == top_it->clip))
            return {1.0f, 1.0f};
    }
 
    // Infer fade direction from which transition edge is closer to this clip.
    const int64_t left_distance = std::llabs(effect_start_position - source_it->start_pos);
    const int64_t right_distance = std::llabs(effect_end_position - source_it->end_pos);
    const bool clip_fades_in = left_distance <= right_distance;
 
    // Evaluate the current frame and previous frame so Timeline can preserve per-frame gain ramps.
    const auto compute_gain = [&](int64_t frame_number) -> float {
        if (effect_end_position <= effect_start_position)
            return 1.0f;
 
        const double span = static_cast<double>(effect_end_position - effect_start_position);
        double t = static_cast<double>(frame_number - effect_start_position) / span;
        if (t < 0.0)
            t = 0.0;
        else if (t > 1.0)
            t = 1.0;
 
        return static_cast<float>(clip_fades_in ? std::sin(t * half_pi) : std::cos(t * half_pi));
    };
 
    return {compute_gain(timeline_frame_number - 1), compute_gain(timeline_frame_number)};
}