libopenshot/include/WriterBase.h

/**
 * @file
 * @brief Header file for WriterBase class
 * @author Jonathan Thomas <jonathan@openshot.org>
 *
 * @section LICENSE
 *
 * Copyright (c) 2008-2014 OpenShot Studios, LLC
 * <http://www.openshotstudios.com/>. This file is part of
 * OpenShot Library (libopenshot), an open-source project dedicated to
 * delivering high quality video editing and animation solutions to the
 * world. For more information visit <http://www.openshot.org/>.
 *
 * OpenShot Library (libopenshot) is free software: you can redistribute it
 * and/or modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * OpenShot Library (libopenshot) is distributed in the hope that it will be
 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with OpenShot Library. If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef OPENSHOT_WRITER_BASE_H
#define OPENSHOT_WRITER_BASE_H

#include <iostream>
#include <iomanip>
#include "ChannelLayouts.h"
#include "Fraction.h"
#include "Frame.h"
#include "ReaderBase.h"

using namespace std;

namespace openshot
{
	/**
	 * @brief This struct contains info about encoding a media file, such as height, width, frames per second, etc...
	 *
	 * Each derived class of WriterBase is responsible for updating this struct to reflect accurate information
	 * about the streams.
	 */
	struct WriterInfo
	{
		bool has_video;				///< Determines if this file has a video stream
		bool has_audio;				///< Determines if this file has an audio stream
		bool has_single_image;		///< Determines if this file only contains a single image
		float duration;				///< Length of time (in seconds)
		int file_size;				///< Size of file (in bytes)
		int height;					///< The height of the video (in pixels)
		int width;					///< The width of the video (in pixels)
		int pixel_format;			///< The pixel format (i.e. YUV420P, RGB24, etc...)
		Fraction fps;				///< Frames per second, as a fraction (i.e. 24/1 = 24 fps)
		int video_bit_rate;			///< The bit rate of the video stream (in bytes)
		Fraction pixel_ratio;		///< The pixel ratio of the video stream as a fraction (i.e. some pixels are not square)
		Fraction display_ratio;		///< The ratio of width to height of the video stream (i.e. 640x480 has a ratio of 4/3)
		string vcodec;				///< The name of the video codec used to encode / decode the video stream
		long int video_length;		///< The number of frames in the video stream
		int video_stream_index;		///< The index of the video stream
		Fraction video_timebase;	///< The video timebase determines how long each frame stays on the screen
		bool interlaced_frame;		///< Are the contents of this frame interlaced
		bool top_field_first;		///< Which interlaced field should be displayed first
		string acodec;				///< The name of the audio codec used to encode / decode the video stream
		int audio_bit_rate;			///< The bit rate of the audio stream (in bytes)
		int sample_rate;			///< The number of audio samples per second (44100 is a common sample rate)
		int channels;				///< The number of audio channels used in the audio stream
		ChannelLayout channel_layout;	///< The channel layout (mono, stereo, 5 point surround, etc...)
		int audio_stream_index;		///< The index of the audio stream
		Fraction audio_timebase;	///< The audio timebase determines how long each audio packet should be played
	};

	/**
	 * @brief This abstract class is the base class, used by writers.  Writers are types of classes that encode
	 * video, audio, and image files.
	 *
	 * The only requirements for a 'writer', are to derive from this base class, and implement the
	 * WriteFrame method.
	 */
	class WriterBase
	{
	protected:

	    /// Debug JSON root
	    Json::Value debug_root;

		/// Append debug information as JSON
		void AppendDebugItem(Json::Value debug_item);

		/// Append debug information as JSON
		void AppendDebugMethod(string method_name, string arg1_name, float arg1_value,
												   string arg2_name, float arg2_value,
												   string arg3_name, float arg3_value,
												   string arg4_name, float arg4_value,
												   string arg5_name, float arg5_value,
												   string arg6_name, float arg6_value);

	public:
		/// Constructor for WriterBase class, many things are initialized here
		WriterBase();

		/// Enable or disable debug output. Output will display on the standard output, and you can
		/// optionally invoke the OutputDebugJSON() method, which will format the debug output as JSON.
		bool debug;

		/// Information about the current media file
		WriterInfo info;

		/// @brief This method copy's the info struct of a reader, and sets the writer with the same info
		/// @param reader The source reader to copy
		void CopyReaderInfo(ReaderBase* reader);

		/// Determine if writer is open or closed
		virtual bool IsOpen() = 0;

		/// This method is required for all derived classes of WriterBase.  Write a Frame to the video file.
		virtual void WriteFrame(tr1::shared_ptr<Frame> frame) throw(ErrorEncodingVideo, WriterClosed) = 0;

		/// This method is required for all derived classes of WriterBase.  Write a block of frames from a reader.
		virtual void WriteFrame(ReaderBase* reader, long int start, long int length) throw(ErrorEncodingVideo, WriterClosed) = 0;

		/// Get and Set JSON methods
		string Json(); ///< Generate JSON string of this object
		Json::Value JsonValue(); ///< Generate Json::JsonValue for this object
		void SetJson(string value) throw(InvalidJSON); ///< Load JSON string into this object
		void SetJsonValue(Json::Value root); ///< Load Json::JsonValue into this object

		/// Display file information in the standard output stream (stdout)
		void DisplayInfo();

		/// Open the writer (and start initializing streams)
		virtual void Open() = 0;

		/// Output debug information as JSON
		string OutputDebugJSON();
	};

}

#endif