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* @brief Header file for CacheDisk class
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* @author Jonathan Thomas <jonathan@openshot.org>
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* Copyright (c) 2008-2014 OpenShot Studios, LLC
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* <http://www.openshotstudios.com/>. This file is part of
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* OpenShot Library (libopenshot), an open-source project dedicated to
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* delivering high quality video editing and animation solutions to the
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* world. For more information visit <http://www.openshot.org/>.
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* OpenShot Library (libopenshot) is free software: you can redistribute it
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* and/or modify it under the terms of the GNU Lesser General Public License
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* as published by the Free Software Foundation, either version 3 of the
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* License, or (at your option) any later version.
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* OpenShot Library (libopenshot) is distributed in the hope that it will be
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* useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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* You should have received a copy of the GNU Lesser General Public License
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* along with OpenShot Library. If not, see <http://www.gnu.org/licenses/>.
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#ifndef OPENSHOT_CACHE_DISK_H
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#define OPENSHOT_CACHE_DISK_H
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#include "CacheBase.h"
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#include "Exceptions.h"
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#include <QTextStream>
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* @brief This class is a disk-based cache manager for Frame objects.
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* It is used by the Timeline class, if enabled, to cache video and audio frames to disk, to cut down on CPU
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* and memory utilization. This will thrash a user's disk, but save their memory and CPU. It's a trade off that
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* sometimes makes perfect sense. You can also set the max number of bytes to cache.
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class CacheDisk : public CacheBase {
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QDir path; ///< This is the folder path of the cache directory
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map<long int, long int> frames; ///< This map holds the frame number and Frame objects
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deque<long int> frame_numbers; ///< This queue holds a sequential list of cached Frame numbers
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long long int frame_size_bytes; ///< The size of the cached frame in bytes
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bool needs_range_processing; ///< Something has changed, and the range data needs to be re-calculated
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Json::Value ranges; ///< JSON ranges of frame numbers
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vector<long int> ordered_frame_numbers; ///< Ordered list of frame numbers used by cache
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map<long int, long int> frame_ranges; ///< This map holds the ranges of frames, useful for quickly displaying the contents of the cache
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long int range_version; ///< The version of the JSON range data (incremented with each change)
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/// Clean up cached frames that exceed the max number of bytes
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/// Init path directory
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void InitPath(string cache_path);
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/// Calculate ranges of frames
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void CalculateRanges();
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/// @brief Default constructor, no max bytes
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/// @param cache_path The folder path of the cache directory (empty string = /tmp/preview-cache/)
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/// @param format The image format for disk caching (ppm, jpg, png)
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/// @param quality The quality of the image (1.0=highest quality/slowest speed, 0.0=worst quality/fastest speed)
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/// @param scale The scale factor for the preview images (1.0 = original size, 0.5=half size, 0.25=quarter size, etc...)
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CacheDisk(string cache_path, string format, float quality, float scale);
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/// @brief Constructor that sets the max bytes to cache
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/// @param cache_path The folder path of the cache directory (empty string = /tmp/preview-cache/)
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/// @param format The image format for disk caching (ppm, jpg, png)
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/// @param quality The quality of the image (1.0=highest quality/slowest speed, 0.0=worst quality/fastest speed)
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/// @param scale The scale factor for the preview images (1.0 = original size, 0.5=half size, 0.25=quarter size, etc...)
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/// @param max_bytes The maximum bytes to allow in the cache. Once exceeded, the cache will purge the oldest frames.
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CacheDisk(string cache_path, string format, float quality, float scale, long long int max_bytes);
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/// @brief Add a Frame to the cache
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/// @param frame The openshot::Frame object needing to be cached.
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void Add(tr1::shared_ptr<Frame> frame);
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/// Clear the cache of all frames
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/// Count the frames in the queue
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/// @brief Get a frame from the cache
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/// @param frame_number The frame number of the cached frame
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tr1::shared_ptr<Frame> GetFrame(long int frame_number);
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/// Gets the maximum bytes value
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long long int GetBytes();
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/// Get the smallest frame number
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tr1::shared_ptr<Frame> GetSmallestFrame();
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/// @brief Move frame to front of queue (so it lasts longer)
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/// @param frame_number The frame number of the cached frame
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void MoveToFront(long int frame_number);
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/// @brief Remove a specific frame
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/// @param frame_number The frame number of the cached frame
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void Remove(long int frame_number);
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/// @brief Remove a range of frames
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/// @param start_frame_number The starting frame number of the cached frame
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/// @param end_frame_number The ending frame number of the cached frame
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void Remove(long int start_frame_number, long int end_frame_number);
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/// Get and Set JSON methods
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string Json(); ///< Generate JSON string of this object
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void SetJson(string value) throw(InvalidJSON); ///< Load JSON string into this object
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Json::Value JsonValue(); ///< Generate Json::JsonValue for this object
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void SetJsonValue(Json::Value root) throw(InvalidFile, ReaderClosed); ///< Load Json::JsonValue into this object