DummyReader.cpp

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// Copyright (c) 2008-2019 OpenShot Studios, LLC
//
// SPDX-License-Identifier: LGPL-3.0-or-later
 
#include "DummyReader.h"
#include "Exceptions.h"
#include "Frame.h"
 
using namespace openshot;
 
// Initialize variables used by constructor
void DummyReader::init(Fraction fps, int width, int height, int sample_rate, int channels, float duration) {
    // Set key info settings
    info.has_audio = false;
    info.has_video = true;
    info.file_size = static_cast<size_t>(width) * height * sizeof(int);
    info.vcodec = "raw";
    info.fps = fps;
    info.width = width;
    info.height = height;
    info.sample_rate = sample_rate;
    info.channels = channels;
    info.duration = duration;
    info.video_length = duration * fps.ToFloat();
    info.pixel_ratio.num = 1;
    info.pixel_ratio.den = 1;
    info.video_timebase = fps.Reciprocal();
    info.acodec = "raw";
 
    // Calculate the DAR (display aspect ratio)
    Fraction size(info.width * info.pixel_ratio.num, info.height * info.pixel_ratio.den);
 
    // Reduce size fraction
    size.Reduce();
 
    // Set the ratio based on the reduced fraction
    info.display_ratio.num = size.num;
    info.display_ratio.den = size.den;
}
 
// Blank constructor for DummyReader, with default settings.
DummyReader::DummyReader() : dummy_cache(NULL), last_cached_frame(NULL), image_frame(NULL), is_open(false) {
 
    // Initialize important variables
    init(Fraction(24,1), 1280, 768, 44100, 2, 30.0);
}
 
// Constructor for DummyReader.  Pass a framerate and samplerate.
DummyReader::DummyReader(Fraction fps, int width, int height, int sample_rate, int channels, float duration) :
    dummy_cache(NULL), last_cached_frame(NULL), image_frame(NULL), is_open(false) {
 
    // Initialize important variables
    init(fps, width, height, sample_rate, channels, duration);
}
 
// Constructor which also takes a cache object
DummyReader::DummyReader(Fraction fps, int width, int height, int sample_rate, int channels, float duration,
                         CacheBase* cache) :  last_cached_frame(NULL), image_frame(NULL), is_open(false) {
 
    // Initialize important variables
    init(fps, width, height, sample_rate, channels, duration);
 
    // Set cache object
    dummy_cache = (CacheBase*) cache;
}
 
DummyReader::~DummyReader() {
}
 
// Open image file
void DummyReader::Open()
{
    // Open reader if not already open
    if (!is_open)
    {
        // Create or get frame object
        image_frame = std::make_shared<Frame>(1, info.width, info.height, "#000000", info.sample_rate, info.channels);
 
        // Mark as "open"
        is_open = true;
    }
}
 
// Close image file
void DummyReader::Close()
{
    // Close all objects, if reader is 'open'
    if (is_open)
    {
        // Mark as "closed"
        is_open = false;
    }
}
 
// Get an openshot::Frame object for a specific frame number of this reader. It is either a blank frame
// or a custom frame added with passing a Cache object to the constructor.
std::shared_ptr<Frame> DummyReader::GetFrame(int64_t requested_frame)
{
    // Check for open reader (or throw exception)
    if (!is_open)
        throw ReaderClosed("The ImageReader is closed.  Call Open() before calling this method.", "dummy");
 
    int dummy_cache_count = 0;
    if (dummy_cache) {
        dummy_cache_count = dummy_cache->Count();
    }
 
    if (dummy_cache_count == 0 && image_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);
 
        // Always return same frame (regardless of which frame number was requested)
        image_frame->number = requested_frame;
        last_cached_frame = image_frame;
        return image_frame;
 
    } else if (dummy_cache_count > 0) {
        // 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);
 
        // Get a frame from the dummy cache
        std::shared_ptr<openshot::Frame> f = dummy_cache->GetFrame(requested_frame);
        if (f) {
            // return frame from cache (if found)
            last_cached_frame = f;
            return f;
        } else if (last_cached_frame) {
            // If available, return last cached frame
            return last_cached_frame;
        } else {
            // No cached frame found
            throw InvalidFile("Requested frame not found. You can only access Frame numbers that exist in the Cache object.", "dummy");
        }
    }
    else
        // no frame loaded
        throw InvalidFile("No frame could be created from this type of file.", "dummy");
}
 
// Generate JSON string of this object
std::string DummyReader::Json() const {
 
    // Return formatted string
    return JsonValue().toStyledString();
}
 
// Generate Json::Value for this object
Json::Value DummyReader::JsonValue() const {
 
    // Create root json object
    Json::Value root = ReaderBase::JsonValue(); // get parent properties
    root["type"] = "DummyReader";
 
    // return JsonValue
    return root;
}
 
// Load JSON string into this object
void DummyReader::SetJson(const std::string value) {
 
    // Parse JSON string into JSON objects
    try
    {
        const Json::Value root = openshot::stringToJson(value);
        // Set all values that match
        SetJsonValue(root);
    }
    catch (const std::exception& e)
    {
        // Error parsing JSON (or missing keys)
        throw InvalidJSON("JSON is invalid (missing keys or invalid data types)");
    }
}
 
// Load Json::Value into this object
void DummyReader::SetJsonValue(const Json::Value root) {
 
    // Set parent data
    ReaderBase::SetJsonValue(root);
 
}