FrameMapper.cpp

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// Copyright (c) 2008-2019 OpenShot Studios, LLC
//
// SPDX-License-Identifier: LGPL-3.0-or-later
 
#include <cmath>
#include <iostream>
#include <iomanip>
 
#include "FrameMapper.h"
#include "Exceptions.h"
#include "Clip.h"
#include "ZmqLogger.h"
 
using namespace std;
using namespace openshot;
 
FrameMapper::FrameMapper(ReaderBase *reader, Fraction target, PulldownType target_pulldown, int target_sample_rate, int target_channels, ChannelLayout target_channel_layout) :
        reader(reader), target(target), pulldown(target_pulldown), is_dirty(true), avr(NULL), parent_position(0.0), parent_start(0.0), previous_frame(0)
{
    // Set the original frame rate from the reader
    original = Fraction(reader->info.fps.num, reader->info.fps.den);
 
    // Set all info struct members equal to the internal reader
    info = reader->info;
    info.fps.num = target.num;
    info.fps.den = target.den;
    info.video_timebase.num = target.den;
    info.video_timebase.den = target.num;
    info.video_length = round(info.duration * info.fps.ToDouble());
    info.sample_rate = target_sample_rate;
    info.channels = target_channels;
    info.channel_layout = target_channel_layout;
    info.width = reader->info.width;
    info.height = reader->info.height;
 
    // Enable/Disable audio (based on settings)
    info.has_audio = info.sample_rate > 0 && info.channels > 0;
 
    // Used to toggle odd / even fields
    field_toggle = true;
 
    // Adjust cache size based on size of frame and audio
    final_cache.SetMaxBytesFromInfo(OPEN_MP_NUM_PROCESSORS, info.width, info.height, info.sample_rate, info.channels);
}
 
// Destructor
FrameMapper::~FrameMapper() {
 
    // Auto Close if not already
    Close();
 
    reader = NULL;
}
 
ReaderBase* FrameMapper::Reader()
{
    if (reader)
        return reader;
    else
        // Throw error if reader not initialized
        throw ReaderClosed("No Reader has been initialized for FrameMapper.  Call Reader(*reader) before calling this method.");
}
 
void FrameMapper::AddField(int64_t frame)
{
    // Add a field, and toggle the odd / even field
    AddField(Field(frame, field_toggle));
}
 
void FrameMapper::AddField(Field field)
{
    // Add a field to the end of the field list
    fields.push_back(field);
 
    // toggle the odd / even flag
    field_toggle = (field_toggle ? false : true);
}
 
// Clear both the fields & frames lists
void FrameMapper::Clear() {
    // Prevent async calls to the following code
    const std::lock_guard<std::recursive_mutex> lock(getFrameMutex);
 
    // Clear the fields & frames lists
    fields.clear();
    fields.shrink_to_fit();
    frames.clear();
    frames.shrink_to_fit();
}
 
// Use the original and target frame rates and a pull-down technique to create
// a mapping between the original fields and frames or a video to a new frame rate.
// This might repeat or skip fields and frames of the original video, depending on
// whether the frame rate is increasing or decreasing.
void FrameMapper::Init()
{
    ZmqLogger::Instance()->AppendDebugMethod("FrameMapper::Init (Calculate frame mappings)");
 
    // Do not initialize anything if just a picture with no audio
    if (info.has_video and !info.has_audio and info.has_single_image)
        // Skip initialization
        return;
 
    // Prevent async calls to the following code
    const std::lock_guard<std::recursive_mutex> lock(getFrameMutex);
 
    // Clear the fields & frames lists
    Clear();
 
    // Find parent position (if any)
    Clip *parent = static_cast<Clip *>(ParentClip());
    if (parent) {
        parent_position = parent->Position();
        parent_start = parent->Start();
    } else {
        parent_position = 0.0;
        parent_start = 0.0;
    }
 
    // Mark as not dirty
    is_dirty = false;
 
    // Clear cache
    final_cache.Clear();
 
    // Some framerates are handled special, and some use a generic Keyframe curve to
    // map the framerates. These are the special framerates:
    if ((fabs(original.ToFloat() - 24.0) < 1e-7 || fabs(original.ToFloat() - 25.0) < 1e-7 || fabs(original.ToFloat() - 30.0) < 1e-7) &&
        (fabs(target.ToFloat() - 24.0) < 1e-7 || fabs(target.ToFloat() - 25.0) < 1e-7 || fabs(target.ToFloat() - 30.0) < 1e-7)) {
 
        // Get the difference (in frames) between the original and target frame rates
        float difference = target.ToInt() - original.ToInt();
 
        // Find the number (i.e. interval) of fields that need to be skipped or repeated
        int field_interval = 0;
        int frame_interval = 0;
 
        if (difference != 0)
        {
            field_interval = round(fabs(original.ToInt() / difference));
 
            // Get frame interval (2 fields per frame)
            frame_interval = field_interval * 2.0f;
        }
 
 
        // Calculate # of fields to map
        int64_t frame = 1;
        int64_t number_of_fields = reader->info.video_length * 2;
 
        // Loop through all fields in the original video file
        for (int64_t field = 1; field <= number_of_fields; field++)
        {
 
            if (difference == 0) // Same frame rate, NO pull-down or special techniques required
            {
                // Add fields
                AddField(frame);
            }
            else if (difference > 0) // Need to ADD fake fields & frames, because original video has too few frames
            {
                // Add current field
                AddField(frame);
 
                if (pulldown == PULLDOWN_CLASSIC && field % field_interval == 0)
                {
                    // Add extra field for each 'field interval
                    AddField(frame);
                }
                else if (pulldown == PULLDOWN_ADVANCED && field % field_interval == 0 && field % frame_interval != 0)
                {
                    // Add both extra fields in the middle 'together' (i.e. 2:3:3:2 technique)
                    AddField(frame); // add field for current frame
 
                    if (frame + 1 <= info.video_length)
                        // add field for next frame (if the next frame exists)
                        AddField(Field(frame + 1, field_toggle));
                }
                else if (pulldown == PULLDOWN_NONE && field % frame_interval == 0)
                {
                    // No pull-down technique needed, just repeat this frame
                    AddField(frame);
                    AddField(frame);
                }
            }
            else if (difference < 0) // Need to SKIP fake fields & frames, because we want to return to the original film frame rate
            {
 
                if (pulldown == PULLDOWN_CLASSIC && field % field_interval == 0)
                {
                    // skip current field and toggle the odd/even flag
                    field_toggle = (field_toggle ? false : true);
                }
                else if (pulldown == PULLDOWN_ADVANCED && field % field_interval == 0 && field % frame_interval != 0)
                {
                    // skip this field, plus the next field
                    field++;
                }
                else if (pulldown == PULLDOWN_NONE && frame % field_interval == 0)
                {
                    // skip this field, plus the next one
                    field++;
                }
                else
                {
                    // No skipping needed, so add the field
                    AddField(frame);
                }
            }
 
            // increment frame number (if field is divisible by 2)
            if (field % 2 == 0 && field > 0)
                frame++;
        }
 
    } else {
        // Map the remaining framerates using a linear algorithm
        double rate_diff = target.ToDouble() / original.ToDouble();
        int64_t new_length = reader->info.video_length * rate_diff;
 
        // Calculate the value difference
        double value_increment = reader->info.video_length / (double) (new_length);
 
        // Loop through curve, and build list of frames
        double original_frame_num = 1.0f;
        for (int64_t frame_num = 1; frame_num <= new_length; frame_num++)
        {
            // Add 2 fields per frame
            AddField(round(original_frame_num));
            AddField(round(original_frame_num));
 
            // Increment original frame number
            original_frame_num += value_increment;
        }
    }
 
    // Loop through the target frames again (combining fields into frames)
    Field Odd(0, true);     // temp field used to track the ODD field
    Field Even(0, true);    // temp field used to track the EVEN field
 
    // Variables used to remap audio samples
    int64_t start_samples_frame = 1;
    int start_samples_position = 0;
 
    for (std::vector<Field>::size_type field = 1; field <= fields.size(); field++)
    {
        // Get the current field
        Field f = fields[field - 1];
 
        // Is field divisible by 2?
        if (field % 2 == 0 && field > 0)
        {
            // New frame number
            int64_t frame_number = field / 2;
 
            // Set the bottom frame
            if (f.isOdd)
                Odd = f;
            else
                Even = f;
 
            // Determine the range of samples (from the original rate). Resampling happens in real-time when
            // calling the GetFrame() method. So this method only needs to redistribute the original samples with
            // the original sample rate.
            int64_t end_samples_frame = start_samples_frame;
            int end_samples_position = start_samples_position;
            int remaining_samples = Frame::GetSamplesPerFrame(AdjustFrameNumber(frame_number), target, reader->info.sample_rate, reader->info.channels);
 
            while (remaining_samples > 0)
            {
                // Get original samples (with NO framerate adjustments)
                // This is the original reader's frame numbers
                int original_samples = Frame::GetSamplesPerFrame(end_samples_frame, original, reader->info.sample_rate, reader->info.channels) - end_samples_position;
 
                // Enough samples
                if (original_samples >= remaining_samples)
                {
                    // Take all that we need, and break loop
                    end_samples_position += remaining_samples - 1;
                    remaining_samples = 0;
                } else
                {
                    // Not enough samples (take them all, and keep looping)
                    end_samples_frame += 1; // next frame
                    end_samples_position = 0; // next frame, starting on 1st sample
                    remaining_samples -= original_samples; // reduce the remaining amount
                }
            }
 
 
 
            // Create the sample mapping struct
            SampleRange Samples = {start_samples_frame, start_samples_position, end_samples_frame, end_samples_position, Frame::GetSamplesPerFrame(AdjustFrameNumber(frame_number), target, reader->info.sample_rate, reader->info.channels)};
 
            // Reset the audio variables
            start_samples_frame = end_samples_frame;
            start_samples_position = end_samples_position + 1;
            if (start_samples_position >= Frame::GetSamplesPerFrame(AdjustFrameNumber(start_samples_frame), original, reader->info.sample_rate, reader->info.channels))
            {
                start_samples_frame += 1; // increment the frame (since we need to wrap onto the next one)
                start_samples_position = 0; // reset to 0, since we wrapped
            }
 
            // Create a frame and ADD it to the frames collection
            MappedFrame frame = {Odd, Even, Samples};
            frames.push_back(frame);
        }
        else
        {
            // Set the top field
            if (f.isOdd)
                Odd = f;
            else
                Even = f;
        }
    }
 
    // Clear the internal fields list (no longer needed)
    fields.clear();
    fields.shrink_to_fit();
 
    if (avr) {
        // Delete resampler (if exists)
        SWR_CLOSE(avr);
        SWR_FREE(&avr);
        avr = NULL;
    }
}
 
MappedFrame FrameMapper::GetMappedFrame(int64_t TargetFrameNumber)
{
    // Check if mappings are dirty (and need to be recalculated)
    if (is_dirty)
        // Recalculate mappings
        Init();
 
    // Ignore mapping on single image readers
    if (info.has_video and !info.has_audio and info.has_single_image) {
        // Return the same number
        MappedFrame frame;
        frame.Even.Frame = TargetFrameNumber;
        frame.Odd.Frame = TargetFrameNumber;
        frame.Samples.frame_start = 0;
        frame.Samples.frame_end = 0;
        frame.Samples.sample_start = 0;
        frame.Samples.sample_end = 0;
        frame.Samples.total = 0;
        return frame;
    }
 
    // Check if frame number is valid
    if(TargetFrameNumber < 1 || frames.size() == 0)
        // frame too small, return error
        throw OutOfBoundsFrame("An invalid frame was requested.", TargetFrameNumber, frames.size());
 
    else if (TargetFrameNumber > (int64_t)frames.size())
        // frame too large, set to end frame
        TargetFrameNumber = frames.size();
 
    // Debug output
    ZmqLogger::Instance()->AppendDebugMethod(
        "FrameMapper::GetMappedFrame",
        "TargetFrameNumber", TargetFrameNumber,
        "frames.size()", frames.size(),
        "frames[...].Odd", frames[TargetFrameNumber - 1].Odd.Frame,
        "frames[...].Even", frames[TargetFrameNumber - 1].Even.Frame);
 
    // Return frame
    return frames[TargetFrameNumber - 1];
}
 
// Get or generate a blank frame
std::shared_ptr<Frame> FrameMapper::GetOrCreateFrame(int64_t number)
{
    std::shared_ptr<Frame> new_frame;
 
    // Init some basic properties about this frame (keep sample rate and # channels the same as the original reader for now)
    int samples_in_frame = Frame::GetSamplesPerFrame(AdjustFrameNumber(number), target, reader->info.sample_rate, reader->info.channels);
 
    try {
        // Debug output
        ZmqLogger::Instance()->AppendDebugMethod(
            "FrameMapper::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 = reader->GetFrame(number);
 
        // Return real frame
        return new_frame;
 
    } catch (const ReaderClosed & e) {
        // ...
    } catch (const OutOfBoundsFrame & e) {
        // ...
    }
 
    // Debug output
    ZmqLogger::Instance()->AppendDebugMethod(
        "FrameMapper::GetOrCreateFrame (create blank)",
        "number", number,
        "samples_in_frame", samples_in_frame);
 
    // Create blank frame
    new_frame = std::make_shared<Frame>(number, info.width, info.height, "#000000", samples_in_frame, reader->info.channels);
    new_frame->SampleRate(reader->info.sample_rate);
    new_frame->ChannelsLayout(info.channel_layout);
    new_frame->AddAudioSilence(samples_in_frame);
    return new_frame;
}
 
// Get an openshot::Frame object for a specific frame number of this reader.
std::shared_ptr<Frame> FrameMapper::GetFrame(int64_t requested_frame)
{
    // Check final cache, and just return the frame (if it's available)
    std::shared_ptr<Frame> final_frame = final_cache.GetFrame(requested_frame);
    if (final_frame) return final_frame;
 
    // Create a scoped lock, allowing only a single thread to run the following code at one time
    const std::lock_guard<std::recursive_mutex> lock(getFrameMutex);
 
    // Find parent properties (if any)
    Clip *parent = static_cast<Clip *>(ParentClip());
    bool is_increasing = true;
    if (parent) {
        float position = parent->Position();
        float start = parent->Start();
        if (parent_position != position || parent_start != start) {
            // Force dirty if parent clip has moved or been trimmed
            // since this heavily affects frame #s and audio mappings
            is_dirty = true;
        }
 
        // Determine direction of parent clip at this frame (forward or reverse direction)
        // This is important for reversing audio in our resampler, for smooth reversed audio.
        is_increasing = parent->time.IsIncreasing(requested_frame);
    }
 
    // Check if mappings are dirty (and need to be recalculated)
    if (is_dirty)
        Init();
 
    // Check final cache a 2nd time (due to potential lock already generating this frame)
    final_frame = final_cache.GetFrame(requested_frame);
    if (final_frame) return final_frame;
 
    // Minimum number of frames to process (for performance reasons)
    // Dialing this down to 1 for now, as it seems to improve performance, and reduce export crashes
    int minimum_frames = 1;
 
    // Debug output
    ZmqLogger::Instance()->AppendDebugMethod(
        "FrameMapper::GetFrame (Loop through frames)",
        "requested_frame", requested_frame,
        "minimum_frames", minimum_frames);
 
    // Loop through all requested frames
    for (int64_t frame_number = requested_frame; frame_number < requested_frame + minimum_frames; frame_number++)
    {
        // Debug output
        ZmqLogger::Instance()->AppendDebugMethod(
            "FrameMapper::GetFrame (inside omp for loop)",
            "frame_number", frame_number,
            "minimum_frames", minimum_frames,
            "requested_frame", requested_frame);
 
        // Get the mapped frame
        MappedFrame mapped = GetMappedFrame(frame_number);
        std::shared_ptr<Frame> mapped_frame = GetOrCreateFrame(mapped.Odd.Frame);
 
        // Get # of channels in the actual frame
        int channels_in_frame = mapped_frame->GetAudioChannelsCount();
        int samples_in_frame = Frame::GetSamplesPerFrame(AdjustFrameNumber(frame_number), target, mapped_frame->SampleRate(), channels_in_frame);
 
        // Determine if mapped frame is identical to source frame
        // including audio sample distribution according to mapped.Samples,
        // and frame_number. In some cases such as end of stream, the reader
        // will return a frame with a different frame number. In these cases,
        // we cannot use the frame as is, nor can we modify the frame number,
        // otherwise the reader's cache object internals become invalid.
        if (info.sample_rate == mapped_frame->SampleRate() &&
            info.channels == mapped_frame->GetAudioChannelsCount() &&
            info.channel_layout == mapped_frame->ChannelsLayout() &&
            mapped.Samples.total == mapped_frame->GetAudioSamplesCount() &&
            mapped.Samples.total == samples_in_frame && is_increasing &&
            mapped.Samples.frame_start == mapped.Odd.Frame &&
            mapped.Samples.sample_start == 0 &&
            mapped_frame->number == frame_number &&// in some conditions (e.g. end of stream)
            info.fps.num == reader->info.fps.num &&
            info.fps.den == reader->info.fps.den) {
                // Add original frame to cache, and skip the rest (for performance reasons)
                final_cache.Add(mapped_frame);
                continue;
        }
 
        // Create a new frame
        auto frame = std::make_shared<Frame>(
            frame_number, 1, 1, "#000000", samples_in_frame, channels_in_frame);
        frame->SampleRate(mapped_frame->SampleRate());
        frame->ChannelsLayout(mapped_frame->ChannelsLayout());
 
 
        // Copy the image from the odd field
        std::shared_ptr<Frame> odd_frame = mapped_frame;
 
        if (odd_frame && odd_frame->has_image_data)
            frame->AddImage(std::make_shared<QImage>(*odd_frame->GetImage()), true);
        if (mapped.Odd.Frame != mapped.Even.Frame) {
            // Add even lines (if different than the previous image)
            std::shared_ptr<Frame> even_frame;
            even_frame = GetOrCreateFrame(mapped.Even.Frame);
            if (even_frame && even_frame->has_image_data)
                frame->AddImage(std::make_shared<QImage>(*even_frame->GetImage()), false);
        }
 
        // Determine if reader contains audio samples
        bool reader_has_audio = frame->SampleRate() > 0 && frame->GetAudioChannelsCount() > 0;
 
        // Resample audio on frame (if needed)
        bool need_resampling = false;
        if ((info.has_audio && reader_has_audio) &&
            (info.sample_rate != frame->SampleRate() ||
             info.channels != frame->GetAudioChannelsCount() ||
             info.channel_layout != frame->ChannelsLayout()))
            // Resample audio and correct # of channels if needed
            need_resampling = true;
 
        // create a copy of mapped.Samples that will be used by copy loop
        SampleRange copy_samples = mapped.Samples;
 
        if (need_resampling)
        {
            // Check for non-adjacent frame requests - so the resampler can be reset
            if (abs(frame->number - previous_frame) > 1) {
                if (avr) {
                    // Delete resampler (if exists)
                    SWR_CLOSE(avr);
                    SWR_FREE(&avr);
                    avr = NULL;
                }
            }
 
            // Resampling needed, modify copy of SampleRange object that includes some additional input samples on
            // first iteration, and continues the offset to ensure that the resampler is not input limited.
            const int EXTRA_INPUT_SAMPLES = 64;
 
            if (!avr) {
                // This is the first iteration, and we need to extend # of samples for this frame
                // Extend sample count range by an additional EXTRA_INPUT_SAMPLES
                copy_samples.Extend(EXTRA_INPUT_SAMPLES, original, reader->info.sample_rate, reader->info.channels, is_increasing);
            } else {
                // Sample rate conversion has already been allocated on this clip, so
                // this is not the first iteration. Shift position by EXTRA_INPUT_SAMPLES to correctly align samples
                copy_samples.Shift(EXTRA_INPUT_SAMPLES, original, reader->info.sample_rate, reader->info.channels, is_increasing);
            }
        }
 
        // Copy the samples
        int samples_copied = 0;
        int64_t starting_frame = copy_samples.frame_start;
        while (info.has_audio && samples_copied < copy_samples.total)
        {
            // Init number of samples to copy this iteration
            int remaining_samples = copy_samples.total - samples_copied;
            int number_to_copy = 0;
 
            // number of original samples on this frame
            std::shared_ptr<Frame> original_frame = mapped_frame;
            if (starting_frame != original_frame->number) {
                original_frame = GetOrCreateFrame(starting_frame);
            }
 
            int original_samples = original_frame->GetAudioSamplesCount();
 
            // Loop through each channel
            for (int channel = 0; channel < channels_in_frame; channel++)
            {
                if (starting_frame == copy_samples.frame_start)
                {
                    // Starting frame (take the ending samples)
                    number_to_copy = original_samples - copy_samples.sample_start;
                    if (number_to_copy > remaining_samples)
                        number_to_copy = remaining_samples;
 
                    // Add samples to new frame
                    frame->AddAudio(true, channel, samples_copied, original_frame->GetAudioSamples(channel) + copy_samples.sample_start, number_to_copy, 1.0);
                }
                else if (starting_frame > copy_samples.frame_start && starting_frame < copy_samples.frame_end)
                {
                    // Middle frame (take all samples)
                    number_to_copy = original_samples;
                    if (number_to_copy > remaining_samples)
                        number_to_copy = remaining_samples;
 
                    // Add samples to new frame
                    frame->AddAudio(true, channel, samples_copied, original_frame->GetAudioSamples(channel), number_to_copy, 1.0);
                }
                else
                {
                    // Ending frame (take the beginning samples)
                    number_to_copy = copy_samples.sample_end + 1;
                    if (number_to_copy > remaining_samples)
                        number_to_copy = remaining_samples;
 
                    // Add samples to new frame
                    frame->AddAudio(false, channel, samples_copied, original_frame->GetAudioSamples(channel), number_to_copy, 1.0);
                }
            }
 
            // increment frame
            samples_copied += number_to_copy;
            starting_frame++;
        }
 
        // Reverse audio (if needed)
        if (!is_increasing)
            frame->ReverseAudio();
 
        // Resample audio on frame (if needed)
        if (need_resampling)
            // Resample audio and correct # of channels if needed
            ResampleMappedAudio(frame, mapped.Odd.Frame);
 
        // Add frame to final cache
        final_cache.Add(frame);
 
    } // for loop
 
    // Return processed openshot::Frame
    return final_cache.GetFrame(requested_frame);
}
 
void FrameMapper::PrintMapping(std::ostream* out)
{
    // Check if mappings are dirty (and need to be recalculated)
    if (is_dirty)
        // Recalculate mappings
        Init();
 
    // Loop through frame mappings
    for (float map = 1; map <= frames.size(); map++)
    {
        MappedFrame frame = frames[map - 1];
        *out << "Target frame #: " << map
             << " mapped to original frame #:\t("
             << frame.Odd.Frame << " odd, "
             << frame.Even.Frame << " even)" << std::endl;
 
        *out << "  - Audio samples mapped to frame "
             << frame.Samples.frame_start << ":"
             << frame.Samples.sample_start << " to frame "
             << frame.Samples.frame_end << ":"
             << frame.Samples.sample_end << endl;
    }
 
}
 
// Determine if reader is open or closed
bool FrameMapper::IsOpen() {
    if (reader)
        return reader->IsOpen();
    else
        return false;
}
 
// Open the internal reader
void FrameMapper::Open()
{
    if (reader)
    {
        ZmqLogger::Instance()->AppendDebugMethod("FrameMapper::Open");
 
        // Open the reader
        reader->Open();
    }
}
 
// Close the internal reader
void FrameMapper::Close()
{
    if (reader)
    {
        // Create a scoped lock, allowing only a single thread to run the following code at one time
        const std::lock_guard<std::recursive_mutex> lock(getFrameMutex);
 
        ZmqLogger::Instance()->AppendDebugMethod("FrameMapper::Close");
 
        // Close internal reader
        reader->Close();
    }
 
    // Clear the fields & frames lists
    Clear();
 
    // Mark as dirty
    is_dirty = true;
 
    // Clear cache
    final_cache.Clear();
 
    // Deallocate resample buffer
    if (avr) {
        SWR_CLOSE(avr);
        SWR_FREE(&avr);
        avr = NULL;
    }
}
 
 
// Generate JSON string of this object
std::string FrameMapper::Json() const {
 
    // Return formatted string
    return JsonValue().toStyledString();
}
 
// Generate Json::Value for this object
Json::Value FrameMapper::JsonValue() const {
 
    // Create root json object
    Json::Value root = ReaderBase::JsonValue(); // get parent properties
    root["type"] = "FrameMapper";
    if (reader) {
        root["reader"] = reader->JsonValue();
    }
 
    // return JsonValue
    return root;
}
 
// Load JSON string into this object
void FrameMapper::SetJson(const std::string value) {
 
    // Parse JSON string into JSON objects
    try
    {
        const Json::Value root = openshot::stringToJson(value);
        // Set all values that match
        SetJsonValue(root);
 
        if (!root["reader"].isNull()) // does Json contain a reader?
        {
            // Placeholder to load reader
            // TODO: need a createReader method for this and Clip JSON methods
        }
    }
    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 FrameMapper::SetJsonValue(const Json::Value root) {
 
    // Set parent data
    ReaderBase::SetJsonValue(root);
 
    // Re-Open path, and re-init everything (if needed)
    if (reader) {
 
        Close();
        Open();
    }
}
 
// Change frame rate or audio mapping details
void FrameMapper::ChangeMapping(Fraction target_fps, PulldownType target_pulldown,  int target_sample_rate, int target_channels, ChannelLayout target_channel_layout)
{
    ZmqLogger::Instance()->AppendDebugMethod(
        "FrameMapper::ChangeMapping",
        "target_fps.num", target_fps.num,
        "target_fps.den", target_fps.den,
        "target_pulldown", target_pulldown,
        "target_sample_rate", target_sample_rate,
        "target_channels", target_channels,
        "target_channel_layout", target_channel_layout);
 
    // Mark as dirty
    is_dirty = true;
 
    // Update mapping details
    target.num = target_fps.num;
    target.den = target_fps.den;
    info.fps.num = target_fps.num;
    info.fps.den = target_fps.den;
    info.video_timebase.num = target_fps.den;
    info.video_timebase.den = target_fps.num;
    info.video_length = round(info.duration * info.fps.ToDouble());
    pulldown = target_pulldown;
    info.sample_rate = target_sample_rate;
    info.channels = target_channels;
    info.channel_layout = target_channel_layout;
 
    // Enable/Disable audio (based on settings)
    info.has_audio = info.sample_rate > 0 && info.channels > 0;
 
    // Clear cache
    final_cache.Clear();
 
    // Adjust cache size based on size of frame and audio
    final_cache.SetMaxBytesFromInfo(OPEN_MP_NUM_PROCESSORS, info.width, info.height, info.sample_rate, info.channels);
 
    // Deallocate resample buffer
    if (avr) {
        SWR_CLOSE(avr);
        SWR_FREE(&avr);
        avr = NULL;
    }
}
 
// Resample audio and map channels (if needed)
void FrameMapper::ResampleMappedAudio(std::shared_ptr<Frame> frame, int64_t original_frame_number)
{
    // Check if mappings are dirty (and need to be recalculated)
    if (is_dirty)
        // Recalculate mappings
        Init();
 
    // Init audio buffers / variables
    int total_frame_samples = 0;
    int channels_in_frame = frame->GetAudioChannelsCount();
    int sample_rate_in_frame = frame->SampleRate();
    int samples_in_frame = frame->GetAudioSamplesCount();
    ChannelLayout channel_layout_in_frame = frame->ChannelsLayout();
 
    ZmqLogger::Instance()->AppendDebugMethod(
        "FrameMapper::ResampleMappedAudio",
        "frame->number", frame->number,
        "original_frame_number", original_frame_number,
        "channels_in_frame", channels_in_frame,
        "samples_in_frame", samples_in_frame,
        "sample_rate_in_frame", sample_rate_in_frame);
 
    // Get audio sample array
    float* frame_samples_float = NULL;
    // Get samples interleaved together (c1 c2 c1 c2 c1 c2)
    frame_samples_float = frame->GetInterleavedAudioSamples(&samples_in_frame);
 
    // Calculate total samples
    total_frame_samples = samples_in_frame * channels_in_frame;
 
    // Create a new array (to hold all S16 audio samples for the current queued frames)
    int16_t* frame_samples = (int16_t*) av_malloc(sizeof(int16_t)*total_frame_samples);
 
    // Translate audio sample values back to 16 bit integers with saturation
    float valF;
    int16_t conv;
    const int16_t max16 = 32767;
    const int16_t min16 = -32768;
    for (int s = 0; s < total_frame_samples; s++) {
        valF = frame_samples_float[s] * (1 << 15);
        if (valF > max16)
            conv = max16;
        else if (valF < min16)
            conv = min16;
        else
            conv = int(valF + 32768.5) - 32768; // +0.5 is for rounding
 
        // Copy into buffer
        frame_samples[s] = conv;
    }
 
    // Deallocate float array
    delete[] frame_samples_float;
    frame_samples_float = NULL;
 
    // Create input frame (and allocate arrays)
    AVFrame *audio_frame = AV_ALLOCATE_FRAME();
    AV_RESET_FRAME(audio_frame);
    audio_frame->nb_samples = total_frame_samples / channels_in_frame;
 
    int buf_size = audio_frame->nb_samples * av_get_bytes_per_sample(AV_SAMPLE_FMT_S16) * channels_in_frame;
    int error_code = avcodec_fill_audio_frame(
        audio_frame, channels_in_frame, AV_SAMPLE_FMT_S16,
        (uint8_t *) frame_samples, buf_size, 1);
 
    if (error_code < 0)
    {
        ZmqLogger::Instance()->AppendDebugMethod(
            "FrameMapper::ResampleMappedAudio ERROR [" + av_err2string(error_code) + "]",
            "error_code", error_code);
        throw ErrorEncodingVideo("Error while resampling audio in frame mapper", frame->number);
    }
 
    // Update total samples & input frame size (due to bigger or smaller data types)
    total_frame_samples = Frame::GetSamplesPerFrame(AdjustFrameNumber(frame->number), target, info.sample_rate, info.channels);
 
    // Create output frame (and allocate arrays)
    AVFrame *audio_converted = AV_ALLOCATE_FRAME();
    AV_RESET_FRAME(audio_converted);
    audio_converted->nb_samples = total_frame_samples;
    av_samples_alloc(audio_converted->data, audio_converted->linesize, info.channels, total_frame_samples, AV_SAMPLE_FMT_S16, 0);
 
    int nb_samples = 0;
 
    // setup resample context
    if (!avr) {
        avr = SWR_ALLOC();
        av_opt_set_int(avr, "in_channel_layout",  channel_layout_in_frame, 0);
        av_opt_set_int(avr, "out_channel_layout", info.channel_layout,   0);
        av_opt_set_int(avr, "in_sample_fmt",      AV_SAMPLE_FMT_S16,       0);
        av_opt_set_int(avr, "out_sample_fmt",    AV_SAMPLE_FMT_S16,    0);
        av_opt_set_int(avr, "in_sample_rate",    sample_rate_in_frame,  0);
        av_opt_set_int(avr, "out_sample_rate",  info.sample_rate,       0);
        av_opt_set_int(avr, "in_channels",      channels_in_frame,     0);
        av_opt_set_int(avr, "out_channels",    info.channels,          0);
        SWR_INIT(avr);
    }
 
    // Convert audio samples
    nb_samples = SWR_CONVERT(avr,     // audio resample context
        audio_converted->data,       // output data pointers
        audio_converted->linesize[0],  // output plane size, in bytes. (0 if unknown)
        audio_converted->nb_samples,   // maximum number of samples that the output buffer can hold
        audio_frame->data,           // input data pointers
        audio_frame->linesize[0],     // input plane size, in bytes (0 if unknown)
        audio_frame->nb_samples);     // number of input samples to convert
 
    // Create a new array (to hold all resampled S16 audio samples)
    int16_t* resampled_samples = new int16_t[(nb_samples * info.channels)];
 
    // Copy audio samples over original samples
    memcpy(resampled_samples, audio_converted->data[0], (nb_samples * av_get_bytes_per_sample(AV_SAMPLE_FMT_S16) * info.channels));
 
    // Free frames
    av_freep(&audio_frame->data[0]);
    AV_FREE_FRAME(&audio_frame);
    av_freep(&audio_converted->data[0]);
    AV_FREE_FRAME(&audio_converted);
    frame_samples = NULL;
 
    // Resize the frame to hold the right # of channels and samples
    int channel_buffer_size = nb_samples;
    frame->ResizeAudio(info.channels, channel_buffer_size, info.sample_rate, info.channel_layout);
 
    ZmqLogger::Instance()->AppendDebugMethod(
        "FrameMapper::ResampleMappedAudio (Audio successfully resampled)",
        "nb_samples", nb_samples,
        "total_frame_samples", total_frame_samples,
        "info.sample_rate", info.sample_rate,
        "channels_in_frame", channels_in_frame,
        "info.channels", info.channels,
        "info.channel_layout", info.channel_layout);
 
    // Array of floats (to hold samples for each channel)
    float *channel_buffer = new float[channel_buffer_size];
 
    // Divide audio into channels. Loop through each channel
    for (int channel_filter = 0; channel_filter < info.channels; channel_filter++)
    {
        // Init array
        for (int z = 0; z < channel_buffer_size; z++)
            channel_buffer[z] = 0.0f;
 
        // Loop through all samples and add them to our Frame based on channel.
        // Toggle through each channel number, since channel data is stored like (left right left right)
        int channel = 0;
        int position = 0;
        for (int sample = 0; sample < (nb_samples * info.channels); sample++)
        {
            // Only add samples for current channel
            if (channel_filter == channel)
            {
                // Add sample (convert from (-32768 to 32768)  to (-1.0 to 1.0))
                channel_buffer[position] = resampled_samples[sample] * (1.0f / (1 << 15));
 
                // Increment audio position
                position++;
            }
 
            // increment channel (if needed)
            if ((channel + 1) < info.channels)
                // move to next channel
                channel ++;
            else
                // reset channel
                channel = 0;
        }
 
        // Add samples to frame for this channel
        frame->AddAudio(true, channel_filter, 0, channel_buffer, position, 1.0f);
    }
 
    // Update frame's audio meta data
    frame->SampleRate(info.sample_rate);
    frame->ChannelsLayout(info.channel_layout);
 
    // clear channel buffer
    delete[] channel_buffer;
    channel_buffer = NULL;
 
    // Delete arrays
    delete[] resampled_samples;
    resampled_samples = NULL;
 
    // Keep track of last resampled frame
    previous_frame = frame->number;
}
 
// Adjust frame number for Clip position and start (which can result in a different number)
int64_t FrameMapper::AdjustFrameNumber(int64_t clip_frame_number) {
 
    // Get clip position from parent clip (if any)
    float position = 0.0;
    float start = 0.0;
    Clip *parent = static_cast<Clip *>(ParentClip());
    if (parent) {
        position = parent->Position();
        start = parent->Start();
    }
 
    // Adjust start frame and position based on parent clip.
    // This ensures the same frame # is used by mapped readers and clips,
    // when calculating samples per frame.
    // Thus, this prevents gaps and mismatches in # of samples.
    int64_t clip_start_frame = (start * info.fps.ToDouble()) + 1;
    int64_t clip_start_position = round(position * info.fps.ToDouble()) + 1;
    int64_t frame_number = clip_frame_number + clip_start_position - clip_start_frame;
 
    return frame_number;
}