/**
 * @file
 * @brief Source file for FFmpegWriter class
 * @author Jonathan Thomas <jonathan@openshot.org>, Fabrice Bellard
 *
 * @ref License
 */

/* LICENSE
 *
 * Copyright (c) 2008-2019 OpenShot Studios, LLC, Fabrice Bellard
 * (http://www.openshotstudios.com). This file is part of
 * OpenShot Library (http://www.openshot.org), an open-source project
 * dedicated to delivering high quality video editing and animation solutions
 * to the world.
 *
 * This file is originally based on the Libavformat API example, and then modified
 * by the libopenshot project.
 *
 * 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/>.
 */

#include "FFmpegWriter.h"
#include "Exceptions.h"

#include <iostream>

using namespace openshot;

// Multiplexer parameters temporary storage
AVDictionary *mux_dict = NULL;

#if USE_HW_ACCEL
int hw_en_on = 1;					// Is set in UI
int hw_en_supported = 0;	// Is set by FFmpegWriter
AVPixelFormat hw_en_av_pix_fmt = AV_PIX_FMT_NONE;
AVHWDeviceType hw_en_av_device_type = AV_HWDEVICE_TYPE_VAAPI;
static AVBufferRef *hw_device_ctx = NULL;
AVFrame *hw_frame = NULL;

static int set_hwframe_ctx(AVCodecContext *ctx, AVBufferRef *hw_device_ctx, int64_t width, int64_t height)
{
	AVBufferRef *hw_frames_ref;
	AVHWFramesContext *frames_ctx = NULL;
	int err = 0;

	if (!(hw_frames_ref = av_hwframe_ctx_alloc(hw_device_ctx))) {
		std::clog << "Failed to create HW frame context.\n";
		return -1;
	}
	frames_ctx = (AVHWFramesContext *)(hw_frames_ref->data);
	frames_ctx->format    = hw_en_av_pix_fmt;
	frames_ctx->sw_format = AV_PIX_FMT_NV12;
	frames_ctx->width     = width;
	frames_ctx->height    = height;
	frames_ctx->initial_pool_size = 20;
	if ((err = av_hwframe_ctx_init(hw_frames_ref)) < 0) {
		std::clog << "Failed to initialize HW frame context. " <<
			"Error code: " << av_err2string(err) << "\n";
		av_buffer_unref(&hw_frames_ref);
		return err;
	}
	ctx->hw_frames_ctx = av_buffer_ref(hw_frames_ref);
	if (!ctx->hw_frames_ctx)
		err = AVERROR(ENOMEM);

	av_buffer_unref(&hw_frames_ref);
	return err;
}
#endif // USE_HW_ACCEL

FFmpegWriter::FFmpegWriter(const std::string& path) :
		path(path), fmt(NULL), oc(NULL), audio_st(NULL), video_st(NULL), samples(NULL),
		audio_outbuf(NULL), audio_outbuf_size(0), audio_input_frame_size(0), audio_input_position(0),
		initial_audio_input_frame_size(0), img_convert_ctx(NULL), cache_size(8), num_of_rescalers(32),
		rescaler_position(0), video_codec_ctx(NULL), audio_codec_ctx(NULL), is_writing(false), video_timestamp(0), audio_timestamp(0),
		original_sample_rate(0), original_channels(0), avr(NULL), avr_planar(NULL), is_open(false), prepare_streams(false),
		write_header(false), write_trailer(false), audio_encoder_buffer_size(0), audio_encoder_buffer(NULL) {

	// Disable audio & video (so they can be independently enabled)
	info.has_audio = false;
	info.has_video = false;

	// Initialize FFMpeg, and register all formats and codecs
	AV_REGISTER_ALL

	// auto detect format
	auto_detect_format();
}

// Open the writer
void FFmpegWriter::Open() {
	if (!is_open) {
		// Open the writer
		is_open = true;

		// Prepare streams (if needed)
		if (!prepare_streams)
			PrepareStreams();

		// Now that all the parameters are set, we can open the audio and video codecs and allocate the necessary encode buffers
		if (info.has_video && video_st)
			open_video(oc, video_st);
		if (info.has_audio && audio_st)
			open_audio(oc, audio_st);

		// Write header (if needed)
		if (!write_header)
			WriteHeader();
	}
}

// auto detect format (from path)
void FFmpegWriter::auto_detect_format() {
	// Auto detect the output format from the name. default is mpeg.
	fmt = av_guess_format(NULL, path.c_str(), NULL);
	if (!fmt)
		throw InvalidFormat("Could not deduce output format from file extension.", path);

	// Allocate the output media context
	AV_OUTPUT_CONTEXT(&oc, path.c_str());
	if (!oc)
		throw OutOfMemory("Could not allocate memory for AVFormatContext.", path);

	// Set the AVOutputFormat for the current AVFormatContext
	oc->oformat = fmt;

	// Update codec names
	if (fmt->video_codec != AV_CODEC_ID_NONE && info.has_video)
		// Update video codec name
		info.vcodec = avcodec_find_encoder(fmt->video_codec)->name;

	if (fmt->audio_codec != AV_CODEC_ID_NONE && info.has_audio)
		// Update audio codec name
		info.acodec = avcodec_find_encoder(fmt->audio_codec)->name;
}

// initialize streams
void FFmpegWriter::initialize_streams() {
	ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::initialize_streams", "fmt->video_codec", fmt->video_codec, "fmt->audio_codec", fmt->audio_codec, "AV_CODEC_ID_NONE", AV_CODEC_ID_NONE);

	// Add the audio and video streams using the default format codecs and initialize the codecs
	video_st = NULL;
	audio_st = NULL;
	if (fmt->video_codec != AV_CODEC_ID_NONE && info.has_video)
		// Add video stream
		video_st = add_video_stream();

	if (fmt->audio_codec != AV_CODEC_ID_NONE && info.has_audio)
		// Add audio stream
		audio_st = add_audio_stream();
}

// Set video export options
void FFmpegWriter::SetVideoOptions(bool has_video, std::string codec, Fraction fps, int width, int height, Fraction pixel_ratio, bool interlaced, bool top_field_first, int bit_rate) {
	// Set the video options
	if (codec.length() > 0) {
		AVCodec *new_codec;
		// Check if the codec selected is a hardware accelerated codec
#if USE_HW_ACCEL
#if defined(__linux__)
		if (strstr(codec.c_str(), "_vaapi") != NULL) {
			new_codec = avcodec_find_encoder_by_name(codec.c_str());
			hw_en_on = 1;
			hw_en_supported = 1;
			hw_en_av_pix_fmt = AV_PIX_FMT_VAAPI;
			hw_en_av_device_type = AV_HWDEVICE_TYPE_VAAPI;
		} else if (strstr(codec.c_str(), "_nvenc") != NULL) {
			new_codec = avcodec_find_encoder_by_name(codec.c_str());
			hw_en_on = 1;
			hw_en_supported = 1;
			hw_en_av_pix_fmt = AV_PIX_FMT_CUDA;
			hw_en_av_device_type = AV_HWDEVICE_TYPE_CUDA;
		} else {
			new_codec = avcodec_find_encoder_by_name(codec.c_str());
			hw_en_on = 0;
			hw_en_supported = 0;
		}
#elif defined(_WIN32)
		if (strstr(codec.c_str(), "_dxva2") != NULL) {
			new_codec = avcodec_find_encoder_by_name(codec.c_str());
			hw_en_on = 1;
			hw_en_supported = 1;
			hw_en_av_pix_fmt = AV_PIX_FMT_DXVA2_VLD;
			hw_en_av_device_type = AV_HWDEVICE_TYPE_DXVA2;
		} else if (strstr(codec.c_str(), "_nvenc") != NULL) {
			new_codec = avcodec_find_encoder_by_name(codec.c_str());
			hw_en_on = 1;
			hw_en_supported = 1;
			hw_en_av_pix_fmt = AV_PIX_FMT_CUDA;
			hw_en_av_device_type = AV_HWDEVICE_TYPE_CUDA;
		} else {
			new_codec = avcodec_find_encoder_by_name(codec.c_str());
			hw_en_on = 0;
			hw_en_supported = 0;
		}
#elif defined(__APPLE__)
		if (strstr(codec.c_str(), "_videotoolbox") != NULL) {
			new_codec = avcodec_find_encoder_by_name(codec.c_str());
			hw_en_on = 1;
			hw_en_supported = 1;
			hw_en_av_pix_fmt = AV_PIX_FMT_VIDEOTOOLBOX;
			hw_en_av_device_type = AV_HWDEVICE_TYPE_VIDEOTOOLBOX;
		} else {
			new_codec = avcodec_find_encoder_by_name(codec.c_str());
			hw_en_on = 0;
			hw_en_supported = 0;
		}
#else  // unknown OS
		new_codec = avcodec_find_encoder_by_name(codec.c_str());
#endif //__linux__/_WIN32/__APPLE__
#else // USE_HW_ACCEL
		new_codec = avcodec_find_encoder_by_name(codec.c_str());
#endif // USE_HW_ACCEL
		if (new_codec == NULL)
			throw InvalidCodec("A valid video codec could not be found for this file.", path);
		else {
			// Set video codec
			info.vcodec = new_codec->name;

			// Update video codec in fmt
			fmt->video_codec = new_codec->id;
		}
	}
	if (fps.num > 0) {
		// Set frames per second (if provided)
		info.fps.num = fps.num;
		info.fps.den = fps.den;

		// Set the timebase (inverse of fps)
		info.video_timebase.num = info.fps.den;
		info.video_timebase.den = info.fps.num;
	}
	if (width >= 1)
		info.width = width;
	if (height >= 1)
		info.height = height;
	if (pixel_ratio.num > 0) {
		info.pixel_ratio.num = pixel_ratio.num;
		info.pixel_ratio.den = pixel_ratio.den;
	}
	if (bit_rate >= 1000)                      // bit_rate is the bitrate in b/s
		info.video_bit_rate = bit_rate;
	if ((bit_rate >= 0) && (bit_rate < 256))   // bit_rate is the bitrate in crf
		info.video_bit_rate = bit_rate;

	info.interlaced_frame = interlaced;
	info.top_field_first = top_field_first;

	// 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;

	ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::SetVideoOptions (" + codec + ")", "width", width, "height", height, "size.num", size.num, "size.den", size.den, "fps.num", fps.num, "fps.den", fps.den);

	// Enable / Disable video
	info.has_video = has_video;
}

// Set video export options (overloaded function)
void FFmpegWriter::SetVideoOptions(std::string codec, int width, int height,  Fraction fps, int bit_rate) {
	// Call full signature with some default parameters
	FFmpegWriter::SetVideoOptions(
		true, codec, fps, width, height,
		openshot::Fraction(1, 1), false, true, bit_rate
	);
}


// Set audio export options
void FFmpegWriter::SetAudioOptions(bool has_audio, std::string codec, int sample_rate, int channels, ChannelLayout channel_layout, int bit_rate) {
	// Set audio options
	if (codec.length() > 0) {
		AVCodec *new_codec = avcodec_find_encoder_by_name(codec.c_str());
		if (new_codec == NULL)
			throw InvalidCodec("A valid audio codec could not be found for this file.", path);
		else {
			// Set audio codec
			info.acodec = new_codec->name;

			// Update audio codec in fmt
			fmt->audio_codec = new_codec->id;
		}
	}
	if (sample_rate > 7999)
		info.sample_rate = sample_rate;
	if (channels > 0)
		info.channels = channels;
	if (bit_rate > 999)
		info.audio_bit_rate = bit_rate;
	info.channel_layout = channel_layout;

	// init resample options (if zero)
	if (original_sample_rate == 0)
		original_sample_rate = info.sample_rate;
	if (original_channels == 0)
		original_channels = info.channels;

	ZmqLogger::Instance()->AppendDebugMethod(
		"FFmpegWriter::SetAudioOptions (" + codec + ")",
		"sample_rate", sample_rate,
		"channels", channels,
		"bit_rate", bit_rate);

	// Enable / Disable audio
	info.has_audio = has_audio;
}


// Set audio export options (overloaded function)
void FFmpegWriter::SetAudioOptions(std::string codec, int sample_rate, int bit_rate) {
	// Call full signature with some default parameters
	FFmpegWriter::SetAudioOptions(
		true, codec, sample_rate, 2,
		openshot::LAYOUT_STEREO, bit_rate
	);
}


// Set custom options (some codecs accept additional params)
void FFmpegWriter::SetOption(StreamType stream, std::string name, std::string value) {
	// Declare codec context
	AVCodecContext *c = NULL;
	AVStream *st = NULL;
	std::stringstream convert(value);

	if (info.has_video && stream == VIDEO_STREAM && video_st) {
		st = video_st;
		// Get codec context
		c = AV_GET_CODEC_PAR_CONTEXT(st, video_codec_ctx);
		// Was a codec / stream found?
		if (c) {
			if (info.interlaced_frame) {
				c->field_order = info.top_field_first ? AV_FIELD_TT : AV_FIELD_BB;
				// We only use these two version and ignore AV_FIELD_TB and AV_FIELD_BT
				// Otherwise we would need to change the whole export window
			}
		}
	} else if (info.has_audio && stream == AUDIO_STREAM && audio_st) {
		st = audio_st;
		// Get codec context
		c = AV_GET_CODEC_PAR_CONTEXT(st, audio_codec_ctx);
	} else
		throw NoStreamsFound("The stream was not found. Be sure to call PrepareStreams() first.", path);

	// Init AVOption
	const AVOption *option = NULL;

	// Was a codec / stream found?
	if (c)
		// Find AVOption (if it exists)
		option = AV_OPTION_FIND(c->priv_data, name.c_str());

	// Was option found?
	if (option || (name == "g" || name == "qmin" || name == "qmax" || name == "max_b_frames" || name == "mb_decision" ||
				   name == "level" || name == "profile" || name == "slices" || name == "rc_min_rate" || name == "rc_max_rate" ||
				   name == "rc_buffer_size" || name == "crf" || name == "cqp" || name == "qp")) {
		// Check for specific named options
		if (name == "g")
			// Set gop_size
			convert >> c->gop_size;

		else if (name == "qmin")
			// Minimum quantizer
			convert >> c->qmin;

		else if (name == "qmax")
			// Maximum quantizer
			convert >> c->qmax;

		else if (name == "max_b_frames")
			// Maximum number of B-frames between non-B-frames
			convert >> c->max_b_frames;

		else if (name == "mb_decision")
			// Macroblock decision mode
			convert >> c->mb_decision;

		else if (name == "level")
			// Set codec level
			convert >> c->level;

		else if (name == "profile")
			// Set codec profile
			convert >> c->profile;

		else if (name == "slices")
			// Indicates number of picture subdivisions
			convert >> c->slices;

		else if (name == "rc_min_rate")
			// Minimum bitrate
			convert >> c->rc_min_rate;

		else if (name == "rc_max_rate")
			// Maximum bitrate
			convert >> c->rc_max_rate;

		else if (name == "rc_buffer_size")
			// Buffer size
			convert >> c->rc_buffer_size;

		else if (name == "cqp") {
			// encode quality and special settings like lossless
			// This might be better in an extra methods as more options
			// and way to set quality are possible
#if USE_HW_ACCEL
			if (hw_en_on) {
				av_opt_set_int(c->priv_data, "qp", std::min(std::stoi(value),63), 0); // 0-63
			} else
#endif // USE_HW_ACCEL
			{
				switch (c->codec_id) {
#if (LIBAVCODEC_VERSION_MAJOR >= 58)
				// FFmpeg 4.0+
				case AV_CODEC_ID_AV1 :
					c->bit_rate = 0;
					av_opt_set_int(c->priv_data, "qp", std::min(std::stoi(value),63), 0); // 0-63
					break;
#endif
				case AV_CODEC_ID_VP8 :
					c->bit_rate = 10000000;
					av_opt_set_int(c->priv_data, "qp", std::max(std::min(std::stoi(value), 63), 4), 0); // 4-63
					break;
				case AV_CODEC_ID_VP9 :
					c->bit_rate = 0;        // Must be zero!
					av_opt_set_int(c->priv_data, "qp", std::min(std::stoi(value), 63), 0); // 0-63
					if (std::stoi(value) == 0) {
						av_opt_set(c->priv_data, "preset", "veryslow", 0);
						av_opt_set_int(c->priv_data, "lossless", 1, 0);
					}
					break;
				case AV_CODEC_ID_H264 :
					av_opt_set_int(c->priv_data, "qp", std::min(std::stoi(value), 51), 0); // 0-51
					if (std::stoi(value) == 0) {
						av_opt_set(c->priv_data, "preset", "veryslow", 0);
							c->pix_fmt = PIX_FMT_YUV444P; // no chroma subsampling
					}
					break;
				case AV_CODEC_ID_HEVC :
					av_opt_set_int(c->priv_data, "qp", std::min(std::stoi(value), 51), 0); // 0-51
					if (std::stoi(value) == 0) {
						av_opt_set(c->priv_data, "preset", "veryslow", 0);
						av_opt_set_int(c->priv_data, "lossless", 1, 0);
					}
					break;
				default:
					// For all other codecs assume a range of 0-63
					av_opt_set_int(c->priv_data, "qp", std::min(std::stoi(value), 63), 0); // 0-63
					c->bit_rate = 0;
				}
			}
		} else if (name == "crf") {
			// encode quality and special settings like lossless
			// This might be better in an extra methods as more options
			// and way to set quality are possible
#if USE_HW_ACCEL
			if (hw_en_on) {
				double mbs = 15000000.0;
				if (info.video_bit_rate > 0) {
					if (info.video_bit_rate > 42) {
						mbs = 380000.0;
					}
					else {
						mbs *= std::pow(0.912,info.video_bit_rate);
					}
				}
				c->bit_rate = (int)(mbs);
			} else
#endif // USE_HW_ACCEL
			{
				switch (c->codec_id) {
#if (LIBAVCODEC_VERSION_MAJOR >= 58)
  				// FFmpeg 4.0+
					case AV_CODEC_ID_AV1 :
						c->bit_rate = 0;
						// AV1 only supports "crf" quality values
						av_opt_set_int(c->priv_data, "crf", std::min(std::stoi(value),63), 0);
						break;
#endif
					case AV_CODEC_ID_VP8 :
						c->bit_rate = 10000000;
						av_opt_set_int(c->priv_data, "crf", std::max(std::min(std::stoi(value), 63), 4), 0); // 4-63
						break;
					case AV_CODEC_ID_VP9 :
						c->bit_rate = 0;        // Must be zero!
						av_opt_set_int(c->priv_data, "crf", std::min(std::stoi(value), 63), 0); // 0-63
						if (std::stoi(value) == 0) {
							av_opt_set(c->priv_data, "preset", "veryslow", 0);
							av_opt_set_int(c->priv_data, "lossless", 1, 0);
						}
						break;
					case AV_CODEC_ID_H264 :
						av_opt_set_int(c->priv_data, "crf", std::min(std::stoi(value), 51), 0); // 0-51
						if (std::stoi(value) == 0) {
							av_opt_set(c->priv_data, "preset", "veryslow", 0);
							c->pix_fmt = PIX_FMT_YUV444P; // no chroma subsampling
						}
						break;
					case AV_CODEC_ID_HEVC :
						if (strstr(info.vcodec.c_str(), "svt_hevc") != NULL) {
							av_opt_set_int(c->priv_data, "preset", 7, 0);
							av_opt_set_int(c->priv_data, "forced-idr",1,0);
							av_opt_set_int(c->priv_data, "qp",std::min(std::stoi(value), 51),0);
						}
						else {
							av_opt_set_int(c->priv_data, "crf", std::min(std::stoi(value), 51), 0); // 0-51
						}
						if (std::stoi(value) == 0) {
							av_opt_set(c->priv_data, "preset", "veryslow", 0);
							av_opt_set_int(c->priv_data, "lossless", 1, 0);
						}
						break;
					default:
						// If this codec doesn't support crf calculate a bitrate
						// TODO: find better formula
						double mbs = 15000000.0;
						if (info.video_bit_rate > 0) {
							if (info.video_bit_rate > 42) {
								mbs = 380000.0;
							} else {
								mbs *= std::pow(0.912, info.video_bit_rate);
							}
						}
						c->bit_rate = (int) (mbs);
				}
			}
		} else if (name == "qp") {
			// encode quality and special settings like lossless
			// This might be better in an extra methods as more options
			// and way to set quality are possible
#if (LIBAVCODEC_VERSION_MAJOR >= 58)
    // FFmpeg 4.0+
				switch (c->codec_id) {
					case AV_CODEC_ID_AV1 :
						c->bit_rate = 0;
						if (strstr(info.vcodec.c_str(), "svtav1") != NULL) {
							av_opt_set_int(c->priv_data, "qp", std::min(std::stoi(value),63), 0);
						}
						else if (strstr(info.vcodec.c_str(), "rav1e") != NULL) {
							// Set number of tiles to a fixed value
							// TODO Let user choose number of tiles
							av_opt_set_int(c->priv_data, "qp", std::min(std::stoi(value),255), 0);
						}
						else if (strstr(info.vcodec.c_str(), "aom") != NULL) {
							// Set number of tiles to a fixed value
							// TODO Let user choose number of tiles
							// libaom doesn't have qp only crf
							av_opt_set_int(c->priv_data, "crf", std::min(std::stoi(value),63), 0);
						}
						else {
							av_opt_set_int(c->priv_data, "crf", std::min(std::stoi(value),63), 0);
						}
					case AV_CODEC_ID_HEVC :
						c->bit_rate = 0;
						if (strstr(info.vcodec.c_str(), "svt_hevc") != NULL) {
							av_opt_set_int(c->priv_data, "qp", std::min(std::stoi(value),51), 0);
							av_opt_set_int(c->priv_data, "preset", 7, 0);
							av_opt_set_int(c->priv_data, "forced-idr",1,0);
						}
						break;
				}
#endif  // FFmpeg 4.0+
		} else {
			// Set AVOption
			AV_OPTION_SET(st, c->priv_data, name.c_str(), value.c_str(), c);
		}

		ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::SetOption (" + (std::string)name + ")", "stream == VIDEO_STREAM", stream == VIDEO_STREAM);

	// Muxing dictionary is not part of the codec context.
	// Just reusing SetOption function to set popular multiplexing presets.
	} else if (name == "muxing_preset") {
		if (value == "mp4_faststart") {
			// 'moov' box to the beginning; only for MOV, MP4
			av_dict_set(&mux_dict, "movflags", "faststart", 0);
		} else if (value == "mp4_fragmented") {
			// write selfcontained fragmented file, minimum length of the fragment 8 sec; only for MOV, MP4
			av_dict_set(&mux_dict, "movflags", "frag_keyframe", 0);
			av_dict_set(&mux_dict, "min_frag_duration", "8000000", 0);
		}
	} else {
		throw InvalidOptions("The option is not valid for this codec.", path);
	}

}

/// Determine if codec name is valid
bool FFmpegWriter::IsValidCodec(std::string codec_name) {
	// Initialize FFMpeg, and register all formats and codecs
	AV_REGISTER_ALL

	// Find the codec (if any)
	if (avcodec_find_encoder_by_name(codec_name.c_str()) == NULL)
		return false;
	else
		return true;
}

// Prepare & initialize streams and open codecs
void FFmpegWriter::PrepareStreams() {
	if (!info.has_audio && !info.has_video)
		throw InvalidOptions("No video or audio options have been set.  You must set has_video or has_audio (or both).", path);

	ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::PrepareStreams [" + path + "]", "info.has_audio", info.has_audio, "info.has_video", info.has_video);

	// Initialize the streams (i.e. add the streams)
	initialize_streams();

	// Mark as 'prepared'
	prepare_streams = true;
}

// Write the file header (after the options are set)
void FFmpegWriter::WriteHeader() {
	if (!info.has_audio && !info.has_video)
		throw InvalidOptions("No video or audio options have been set.  You must set has_video or has_audio (or both).", path);

	// Open the output file, if needed
	if (!(fmt->flags & AVFMT_NOFILE)) {
		if (avio_open(&oc->pb, path.c_str(), AVIO_FLAG_WRITE) < 0)
			throw InvalidFile("Could not open or write file.", path);
	}

	// Force the output filename (which doesn't always happen for some reason)
	AV_SET_FILENAME(oc, path.c_str());

	// Add general metadata (if any)
	for (std::map<std::string, std::string>::iterator iter = info.metadata.begin(); iter != info.metadata.end(); ++iter) {
		av_dict_set(&oc->metadata, iter->first.c_str(), iter->second.c_str(), 0);
	}

	// Set multiplexing parameters
	AVDictionary *dict = NULL;

	bool is_mp4 = strcmp(oc->oformat->name, "mp4");
	bool is_mov = strcmp(oc->oformat->name, "mov");
	// Set dictionary preset only for MP4 and MOV files
	if (is_mp4 || is_mov)
		av_dict_copy(&dict, mux_dict, 0);

	// Write the stream header
	if (avformat_write_header(oc, &dict) != 0) {
		ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::WriteHeader (avformat_write_header)");
		throw InvalidFile("Could not write header to file.", path);
	};

	// Free multiplexing dictionaries sets
	if (dict) av_dict_free(&dict);
	if (mux_dict) av_dict_free(&mux_dict);

	// Mark as 'written'
	write_header = true;

	ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::WriteHeader");
}

// Add a frame to the queue waiting to be encoded.
void FFmpegWriter::WriteFrame(std::shared_ptr<Frame> frame) {
	// Check for open reader (or throw exception)
	if (!is_open)
		throw WriterClosed("The FFmpegWriter is closed.  Call Open() before calling this method.", path);

	// Add frame pointer to "queue", waiting to be processed the next
	// time the WriteFrames() method is called.
	if (info.has_video && video_st)
		spooled_video_frames.push_back(frame);

	if (info.has_audio && audio_st)
		spooled_audio_frames.push_back(frame);

	ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::WriteFrame", "frame->number", frame->number, "spooled_video_frames.size()", spooled_video_frames.size(), "spooled_audio_frames.size()", spooled_audio_frames.size(), "cache_size", cache_size, "is_writing", is_writing);

	// Write the frames once it reaches the correct cache size
	if ((int)spooled_video_frames.size() == cache_size || (int)spooled_audio_frames.size() == cache_size) {
		// Write frames to video file
		write_queued_frames();
	}

	// Keep track of the last frame added
	last_frame = frame;
}

// Write all frames in the queue to the video file.
void FFmpegWriter::write_queued_frames() {
	ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::write_queued_frames", "spooled_video_frames.size()", spooled_video_frames.size(), "spooled_audio_frames.size()", spooled_audio_frames.size());

	// Flip writing flag
	is_writing = true;

	// Transfer spool to queue
	queued_video_frames = spooled_video_frames;
	queued_audio_frames = spooled_audio_frames;

	// Empty spool
	spooled_video_frames.clear();
	spooled_audio_frames.clear();

	// Create blank exception
	bool has_error_encoding_video = false;

    // Process all audio frames (in a separate thread)
    if (info.has_audio && audio_st && !queued_audio_frames.empty())
        write_audio_packets(false);

    // Loop through each queued image frame
    while (!queued_video_frames.empty()) {
        // Get front frame (from the queue)
        std::shared_ptr<Frame> frame = queued_video_frames.front();

        // Add to processed queue
        processed_frames.push_back(frame);

        // Encode and add the frame to the output file
        if (info.has_video && video_st)
            process_video_packet(frame);

        // Remove front item
        queued_video_frames.pop_front();

    } // end while


    // Loop back through the frames (in order), and write them to the video file
    while (!processed_frames.empty()) {
        // Get front frame (from the queue)
        std::shared_ptr<Frame> frame = processed_frames.front();

        if (info.has_video && video_st) {
            // Add to deallocate queue (so we can remove the AVFrames when we are done)
            deallocate_frames.push_back(frame);

            // Does this frame's AVFrame still exist
            if (av_frames.count(frame)) {
                // Get AVFrame
                AVFrame *frame_final = av_frames[frame];

                // Write frame to video file
                bool success = write_video_packet(frame, frame_final);
                if (!success)
                    has_error_encoding_video = true;
            }
        }

        // Remove front item
        processed_frames.pop_front();
    }

    // Loop through, and deallocate AVFrames
    while (!deallocate_frames.empty()) {
        // Get front frame (from the queue)
        std::shared_ptr<Frame> frame = deallocate_frames.front();

        // Does this frame's AVFrame still exist
        if (av_frames.count(frame)) {
            // Get AVFrame
            AVFrame *av_frame = av_frames[frame];

            // Deallocate AVPicture and AVFrame
            av_freep(&(av_frame->data[0]));
            AV_FREE_FRAME(&av_frame);
            av_frames.erase(frame);
        }

        // Remove front item
        deallocate_frames.pop_front();
    }

    // Done writing
    is_writing = false;

	// Raise exception from main thread
	if (has_error_encoding_video)
		throw ErrorEncodingVideo("Error while writing raw video frame", -1);
}

// Write a block of frames from a reader
void FFmpegWriter::WriteFrame(ReaderBase *reader, int64_t start, int64_t length) {
	ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::WriteFrame (from Reader)", "start", start, "length", length);

	// Loop through each frame (and encoded it)
	for (int64_t number = start; number <= length; number++) {
		// Get the frame
		std::shared_ptr<Frame> f = reader->GetFrame(number);

		// Encode frame
		WriteFrame(f);
	}
}

// Write the file trailer (after all frames are written)
void FFmpegWriter::WriteTrailer() {
	// Write any remaining queued frames to video file
	write_queued_frames();

	// Process final audio frame (if any)
	if (info.has_audio && audio_st)
		write_audio_packets(true);

	// Flush encoders (who sometimes hold on to frames)
	flush_encoders();

	/* write the trailer, if any. The trailer must be written
	 * before you close the CodecContexts open when you wrote the
	 * header; otherwise write_trailer may try to use memory that
	 * was freed on av_codec_close() */
	av_write_trailer(oc);

	// Mark as 'written'
	write_trailer = true;

	ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::WriteTrailer");
}

// Flush encoders
void FFmpegWriter::flush_encoders() {
	if (info.has_audio && audio_codec_ctx && AV_GET_CODEC_TYPE(audio_st) == AVMEDIA_TYPE_AUDIO && AV_GET_CODEC_ATTRIBUTES(audio_st, audio_codec_ctx)->frame_size <= 1)
		return;
#if (LIBAVFORMAT_VERSION_MAJOR < 58)
	// FFmpeg < 4.0
	if (info.has_video && video_codec_ctx && AV_GET_CODEC_TYPE(video_st) == AVMEDIA_TYPE_VIDEO && (oc->oformat->flags & AVFMT_RAWPICTURE) && AV_FIND_DECODER_CODEC_ID(video_st) == AV_CODEC_ID_RAWVIDEO)
		return;
#else
	if (info.has_video && video_codec_ctx && AV_GET_CODEC_TYPE(video_st) == AVMEDIA_TYPE_VIDEO && AV_FIND_DECODER_CODEC_ID(video_st) == AV_CODEC_ID_RAWVIDEO)
		return;
#endif

	// FLUSH VIDEO ENCODER
	if (info.has_video)
		for (;;) {

			// Increment PTS (in frames and scaled to the codec's timebase)
            video_timestamp += av_rescale_q(1, av_make_q(info.fps.den, info.fps.num), video_codec_ctx->time_base);

			AVPacket pkt;
			av_init_packet(&pkt);
			pkt.data = NULL;
			pkt.size = 0;

			/* encode the image */
			int got_packet = 0;
			int error_code = 0;

#if IS_FFMPEG_3_2
            // Encode video packet (latest version of FFmpeg)
            error_code = avcodec_send_frame(video_codec_ctx, NULL);
            got_packet = 0;
            while (error_code >= 0) {
                error_code = avcodec_receive_packet(video_codec_ctx, &pkt);
                if (error_code == AVERROR(EAGAIN)|| error_code == AVERROR_EOF) {
                    got_packet = 0;
                    // Write packet
                    avcodec_flush_buffers(video_codec_ctx);
                    break;
                }
                av_packet_rescale_ts(&pkt, video_codec_ctx->time_base, video_st->time_base);
                pkt.stream_index = video_st->index;
                error_code = av_interleaved_write_frame(oc, &pkt);
            }
#else // IS_FFMPEG_3_2

			// Encode video packet (older than FFmpeg 3.2)
			error_code = avcodec_encode_video2(video_codec_ctx, &pkt, NULL, &got_packet);

#endif // IS_FFMPEG_3_2

			if (error_code < 0) {
				ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::flush_encoders ERROR [" + av_err2string(error_code) + "]", "error_code", error_code);
			}
			if (!got_packet) {
				break;
			}

			// set the timestamp
            av_packet_rescale_ts(&pkt, video_codec_ctx->time_base, video_st->time_base);
			pkt.stream_index = video_st->index;

			// Write packet
			error_code = av_interleaved_write_frame(oc, &pkt);
			if (error_code < 0) {
				ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::flush_encoders ERROR [" + av_err2string(error_code) + "]", "error_code", error_code);
			}
		}

	// FLUSH AUDIO ENCODER
	if (info.has_audio) {
        for (;;) {
            AVPacket pkt;
            av_init_packet(&pkt);
            pkt.data = NULL;
            pkt.size = 0;
            pkt.pts = pkt.dts = audio_timestamp;

            /* encode the image */
            int error_code = 0;
            int got_packet = 0;
#if IS_FFMPEG_3_2
            error_code = avcodec_send_frame(audio_codec_ctx, NULL);
#else
            error_code = avcodec_encode_audio2(audio_codec_ctx, &pkt, NULL, &got_packet);
#endif
            if (error_code < 0) {
                ZmqLogger::Instance()->AppendDebugMethod(
                        "FFmpegWriter::flush_encoders ERROR [" + av_err2string(error_code) + "]",
                        "error_code", error_code);
            }
            if (!got_packet) {
                break;
            }

            // Since the PTS can change during encoding, set the value again.  This seems like a huge hack,
            // but it fixes lots of PTS related issues when I do this.
            pkt.pts = pkt.dts = audio_timestamp;

            // Scale the PTS to the audio stream timebase (which is sometimes different than the codec's timebase)
            av_packet_rescale_ts(&pkt, audio_codec_ctx->time_base, audio_st->time_base);

            // set stream
            pkt.stream_index = audio_st->index;
            pkt.flags |= AV_PKT_FLAG_KEY;

            // Write packet
            error_code = av_interleaved_write_frame(oc, &pkt);
            if (error_code < 0) {
                ZmqLogger::Instance()->AppendDebugMethod(
                        "FFmpegWriter::flush_encoders ERROR [" + av_err2string(error_code) + "]",
                        "error_code", error_code);
            }

            // Increment PTS by duration of packet
            audio_timestamp += pkt.duration;

            // deallocate memory for packet
            AV_FREE_PACKET(&pkt);
        }
    }

}

// Close the video codec
void FFmpegWriter::close_video(AVFormatContext *oc, AVStream *st)
{
#if USE_HW_ACCEL
	if (hw_en_on && hw_en_supported) {
		if (hw_device_ctx) {
			av_buffer_unref(&hw_device_ctx);
			hw_device_ctx = NULL;
		}
	}
#endif // USE_HW_ACCEL
}

// Close the audio codec
void FFmpegWriter::close_audio(AVFormatContext *oc, AVStream *st)
{
	// Clear buffers
	delete[] samples;
	delete[] audio_outbuf;
	delete[] audio_encoder_buffer;
	samples = NULL;
	audio_outbuf = NULL;
	audio_encoder_buffer = NULL;

	// Deallocate resample buffer
	if (avr) {
		SWR_CLOSE(avr);
		SWR_FREE(&avr);
		avr = NULL;
	}

	if (avr_planar) {
		SWR_CLOSE(avr_planar);
		SWR_FREE(&avr_planar);
		avr_planar = NULL;
	}
}

// Close the writer
void FFmpegWriter::Close() {
	// Write trailer (if needed)
	if (!write_trailer)
		WriteTrailer();

	// Close each codec
	if (video_st)
		close_video(oc, video_st);
	if (audio_st)
		close_audio(oc, audio_st);

	// Deallocate image scalers
	if (image_rescalers.size() > 0)
		RemoveScalers();

	if (!(fmt->flags & AVFMT_NOFILE)) {
		/* close the output file */
		avio_close(oc->pb);
	}

	// Reset frame counters
    video_timestamp = 0;
    audio_timestamp = 0;

	// Free the context which frees the streams too
	avformat_free_context(oc);
	oc = NULL;

	// Close writer
	is_open = false;
	prepare_streams = false;
	write_header = false;
	write_trailer = false;

	ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::Close");
}

// Add an AVFrame to the cache
void FFmpegWriter::add_avframe(std::shared_ptr<Frame> frame, AVFrame *av_frame) {
	// Add AVFrame to map (if it does not already exist)
	if (!av_frames.count(frame)) {
		// Add av_frame
		av_frames[frame] = av_frame;
	} else {
		// Do not add, and deallocate this AVFrame
		AV_FREE_FRAME(&av_frame);
	}
}

// Add an audio output stream
AVStream *FFmpegWriter::add_audio_stream() {
	AVCodecContext *c;
	AVStream *st;

	// Find the audio codec
	AVCodec *codec = avcodec_find_encoder_by_name(info.acodec.c_str());
	if (codec == NULL)
		throw InvalidCodec("A valid audio codec could not be found for this file.", path);

	// Free any previous memory allocations
	if (audio_codec_ctx != NULL) {
		AV_FREE_CONTEXT(audio_codec_ctx);
	}

	// Create a new audio stream
	AV_FORMAT_NEW_STREAM(oc, audio_codec_ctx, codec, st)

	c->codec_id = codec->id;
	c->codec_type = AVMEDIA_TYPE_AUDIO;

	// Set the sample parameters
	c->bit_rate = info.audio_bit_rate;
	c->channels = info.channels;

	// Set valid sample rate (or throw error)
	if (codec->supported_samplerates) {
		int i;
		for (i = 0; codec->supported_samplerates[i] != 0; i++)
			if (info.sample_rate == codec->supported_samplerates[i]) {
				// Set the valid sample rate
				c->sample_rate = info.sample_rate;
				break;
			}
		if (codec->supported_samplerates[i] == 0)
			throw InvalidSampleRate("An invalid sample rate was detected for this codec.", path);
	} else
		// Set sample rate
		c->sample_rate = info.sample_rate;


	// Set a valid number of channels (or throw error)
	const uint64_t channel_layout = info.channel_layout;
	if (codec->channel_layouts) {
		int i;
		for (i = 0; codec->channel_layouts[i] != 0; i++)
			if (channel_layout == codec->channel_layouts[i]) {
				// Set valid channel layout
				c->channel_layout = channel_layout;
				break;
			}
		if (codec->channel_layouts[i] == 0)
			throw InvalidChannels("An invalid channel layout was detected (i.e. MONO / STEREO).", path);
	} else
		// Set valid channel layout
		c->channel_layout = channel_layout;

	// Choose a valid sample_fmt
	if (codec->sample_fmts) {
		for (int i = 0; codec->sample_fmts[i] != AV_SAMPLE_FMT_NONE; i++) {
			// Set sample format to 1st valid format (and then exit loop)
			c->sample_fmt = codec->sample_fmts[i];
			break;
		}
	}
	if (c->sample_fmt == AV_SAMPLE_FMT_NONE) {
		// Default if no sample formats found
		c->sample_fmt = AV_SAMPLE_FMT_S16;
	}

	// some formats want stream headers to be separate
	if (oc->oformat->flags & AVFMT_GLOBALHEADER)
#if (LIBAVCODEC_VERSION_MAJOR >= 57)
		// FFmpeg 3.0+
		c->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
#else
		c->flags |= CODEC_FLAG_GLOBAL_HEADER;
#endif

	AV_COPY_PARAMS_FROM_CONTEXT(st, c);
	ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::add_audio_stream", "c->codec_id", c->codec_id, "c->bit_rate", c->bit_rate, "c->channels", c->channels, "c->sample_fmt", c->sample_fmt, "c->channel_layout", c->channel_layout, "c->sample_rate", c->sample_rate);

	return st;
}

// Add a video output stream
AVStream *FFmpegWriter::add_video_stream() {
	AVCodecContext *c;
	AVStream *st;

	// Find the video codec
	AVCodec *codec = avcodec_find_encoder_by_name(info.vcodec.c_str());
	if (codec == NULL)
		throw InvalidCodec("A valid video codec could not be found for this file.", path);

	// Create a new video stream
	AV_FORMAT_NEW_STREAM(oc, video_codec_ctx, codec, st)

	c->codec_id = codec->id;
	c->codec_type = AVMEDIA_TYPE_VIDEO;

	/* Init video encoder options */
	if (info.video_bit_rate >= 1000
#if (LIBAVCODEC_VERSION_MAJOR >= 58)
		&& c->codec_id != AV_CODEC_ID_AV1
#endif
		) {
		c->bit_rate = info.video_bit_rate;
		if (info.video_bit_rate >= 1500000) {
			if (c->codec_id == AV_CODEC_ID_MPEG2VIDEO)  {
				c->qmin = 2;
				c->qmax = 30;
			}
		}
		// Here should be the setting for low fixed bitrate
		// Defaults are used because mpeg2 otherwise had problems
	} else {
		// Check if codec supports crf or qp
		switch (c->codec_id) {
#if (LIBAVCODEC_VERSION_MAJOR >= 58)
			// FFmpeg 4.0+
			case AV_CODEC_ID_AV1 :
			// TODO: Set `crf` or `qp` according to bitrate, as bitrate is not supported by these encoders yet.
			if (info.video_bit_rate >= 1000) {
				c->bit_rate = 0;
				if (strstr(info.vcodec.c_str(), "aom") != NULL) {
					int calculated_quality = 35;
					if (info.video_bit_rate < 500000) calculated_quality = 50;
					if (info.video_bit_rate > 5000000) calculated_quality = 10;
					av_opt_set_int(c->priv_data, "crf", calculated_quality, 0);
					info.video_bit_rate = calculated_quality;
				} else {
					int calculated_quality = 50;
					if (info.video_bit_rate < 500000) calculated_quality = 60;
					if (info.video_bit_rate > 5000000) calculated_quality = 15;
					av_opt_set_int(c->priv_data, "qp", calculated_quality, 0);
					info.video_bit_rate = calculated_quality;
				} // medium
			}
			if (strstr(info.vcodec.c_str(), "svtav1") != NULL) {
				av_opt_set_int(c->priv_data, "preset", 6, 0);
				av_opt_set_int(c->priv_data, "forced-idr",1,0);
			}
			else if (strstr(info.vcodec.c_str(), "rav1e") != NULL) {
				av_opt_set_int(c->priv_data, "speed", 7, 0);
				av_opt_set_int(c->priv_data, "tile-rows", 2, 0);
				av_opt_set_int(c->priv_data, "tile-columns", 4, 0);
			}
			else if (strstr(info.vcodec.c_str(), "aom") != NULL) {
				// Set number of tiles to a fixed value
				// TODO: Allow user to chose their own number of tiles
				av_opt_set_int(c->priv_data, "tile-rows", 1, 0);		// log2 of number of rows
				av_opt_set_int(c->priv_data, "tile-columns", 2, 0);		// log2 of number of columns
				av_opt_set_int(c->priv_data, "row-mt", 1, 0);			// use multiple cores
				av_opt_set_int(c->priv_data, "cpu-used", 3, 0);			// default is 1, usable is 4
			}
			//break;
#endif
			case AV_CODEC_ID_VP9 :
			case AV_CODEC_ID_HEVC :
			case AV_CODEC_ID_VP8 :
			case AV_CODEC_ID_H264 :
				if (info.video_bit_rate < 40) {
					c->qmin = 0;
					c->qmax = 63;
				} else {
					c->qmin = info.video_bit_rate - 5;
					c->qmax = 63;
				}
				break;
			default:
				// Here should be the setting for codecs that don't support crf
				// For now defaults are used
				break;
		}
	}

//TODO: Implement variable bitrate feature (which actually works). This implementation throws
	//invalid bitrate errors and rc buffer underflow errors, etc...
	//c->rc_min_rate = info.video_bit_rate;
	//c->rc_max_rate = info.video_bit_rate;
	//c->rc_buffer_size = FFMAX(c->rc_max_rate, 15000000) * 112L / 15000000 * 16384;
	//if ( !c->rc_initial_buffer_occupancy )
	//	c->rc_initial_buffer_occupancy = c->rc_buffer_size * 3/4;

	/* resolution must be a multiple of two */
	// TODO: require /2 height and width
	c->width = info.width;
	c->height = info.height;

	/* time base: this is the fundamental unit of time (in seconds) in terms
	 of which frame timestamps are represented. for fixed-fps content,
	 timebase should be 1/framerate and timestamp increments should be
	 identically 1. */
	c->time_base.num = info.video_timebase.num;
	c->time_base.den = info.video_timebase.den;
// AVCodecContext->framerate was added in FFmpeg 2.6
#if LIBAVCODEC_VERSION_INT >= AV_VERSION_INT(56, 26, 0)
	c->framerate = av_inv_q(c->time_base);
#endif
	st->avg_frame_rate = av_inv_q(c->time_base);
	st->time_base.num = info.video_timebase.num;
	st->time_base.den = info.video_timebase.den;
#if (LIBAVFORMAT_VERSION_MAJOR >= 58)
	#pragma GCC diagnostic push
	#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
	st->codec->time_base.num = info.video_timebase.num;
	st->codec->time_base.den = info.video_timebase.den;
	#pragma GCC diagnostic pop
#endif

	c->gop_size = 12; /* TODO: add this to "info"... emit one intra frame every twelve frames at most */
	c->max_b_frames = 10;
	if (c->codec_id == AV_CODEC_ID_MPEG2VIDEO)
		/* just for testing, we also add B frames */
		c->max_b_frames = 2;
	if (c->codec_id == AV_CODEC_ID_MPEG1VIDEO)
		/* Needed to avoid using macroblocks in which some coeffs overflow.
		 This does not happen with normal video, it just happens here as
		 the motion of the chroma plane does not match the luma plane. */
		c->mb_decision = 2;
	// some formats want stream headers to be separate
	if (oc->oformat->flags & AVFMT_GLOBALHEADER)
#if (LIBAVCODEC_VERSION_MAJOR >= 57)
		// FFmpeg 3.0+
		c->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
#else
		c->flags |= CODEC_FLAG_GLOBAL_HEADER;
#endif

	// Find all supported pixel formats for this codec
	const PixelFormat *supported_pixel_formats = codec->pix_fmts;
	while (supported_pixel_formats != NULL && *supported_pixel_formats != PIX_FMT_NONE) {
		// Assign the 1st valid pixel format (if one is missing)
		if (c->pix_fmt == PIX_FMT_NONE)
			c->pix_fmt = *supported_pixel_formats;
		++supported_pixel_formats;
	}

	// Codec doesn't have any pix formats?
	if (c->pix_fmt == PIX_FMT_NONE) {
		if (fmt->video_codec == AV_CODEC_ID_RAWVIDEO) {
			// Raw video should use RGB24
			c->pix_fmt = PIX_FMT_RGB24;

#if (LIBAVFORMAT_VERSION_MAJOR < 58)
			// FFmpeg < 4.0
			if (strcmp(fmt->name, "gif") != 0)
				// If not GIF format, skip the encoding process
				// Set raw picture flag (so we don't encode this video)
				oc->oformat->flags |= AVFMT_RAWPICTURE;
#endif
		} else {
			// Set the default codec
			c->pix_fmt = PIX_FMT_YUV420P;
		}
	}

	AV_COPY_PARAMS_FROM_CONTEXT(st, c);
#if (LIBAVFORMAT_VERSION_MAJOR < 58)
	// FFmpeg < 4.0
	ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::add_video_stream (" + (std::string)fmt->name + " : " + (std::string)av_get_pix_fmt_name(c->pix_fmt) + ")", "c->codec_id", c->codec_id, "c->bit_rate", c->bit_rate, "c->pix_fmt", c->pix_fmt, "oc->oformat->flags", oc->oformat->flags, "AVFMT_RAWPICTURE", AVFMT_RAWPICTURE);
#else
	ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::add_video_stream (" + (std::string)fmt->name + " : " + (std::string)av_get_pix_fmt_name(c->pix_fmt) + ")", "c->codec_id", c->codec_id, "c->bit_rate", c->bit_rate, "c->pix_fmt", c->pix_fmt, "oc->oformat->flags", oc->oformat->flags);
#endif

	return st;
}

// open audio codec
void FFmpegWriter::open_audio(AVFormatContext *oc, AVStream *st) {
	AVCodec *codec;
	AV_GET_CODEC_FROM_STREAM(st, audio_codec_ctx)

	// Set number of threads equal to number of processors (not to exceed 16)
	audio_codec_ctx->thread_count = std::min(FF_NUM_PROCESSORS, 16);

	// Find the audio encoder
	codec = avcodec_find_encoder_by_name(info.acodec.c_str());
	if (!codec)
		codec = avcodec_find_encoder(audio_codec_ctx->codec_id);
	if (!codec)
		throw InvalidCodec("Could not find codec", path);

	// Init options
	AVDictionary *opts = NULL;
	av_dict_set(&opts, "strict", "experimental", 0);

	// Open the codec
	if (avcodec_open2(audio_codec_ctx, codec, &opts) < 0)
		throw InvalidCodec("Could not open audio codec", path);
	AV_COPY_PARAMS_FROM_CONTEXT(st, audio_codec_ctx);

	// Free options
	av_dict_free(&opts);

	// Calculate the size of the input frame (i..e how many samples per packet), and the output buffer
	// TODO: Ugly hack for PCM codecs (will be removed ASAP with new PCM support to compute the input frame size in samples
	if (audio_codec_ctx->frame_size <= 1) {
		// No frame size found... so calculate
		audio_input_frame_size = 50000 / info.channels;

		int s = AV_FIND_DECODER_CODEC_ID(st);
		switch (s) {
			case AV_CODEC_ID_PCM_S16LE:
			case AV_CODEC_ID_PCM_S16BE:
			case AV_CODEC_ID_PCM_U16LE:
			case AV_CODEC_ID_PCM_U16BE:
				audio_input_frame_size >>= 1;
				break;
			default:
				break;
		}
	} else {
		// Set frame size based on the codec
		audio_input_frame_size = audio_codec_ctx->frame_size;
	}

	// Set the initial frame size (since it might change during resampling)
	initial_audio_input_frame_size = audio_input_frame_size;

	// Allocate array for samples
	samples = new int16_t[AVCODEC_MAX_AUDIO_FRAME_SIZE];

	// Set audio output buffer (used to store the encoded audio)
	audio_outbuf_size = AVCODEC_MAX_AUDIO_FRAME_SIZE;
	audio_outbuf = new uint8_t[audio_outbuf_size];

	// Set audio packet encoding buffer
	audio_encoder_buffer_size = AUDIO_PACKET_ENCODING_SIZE;
	audio_encoder_buffer = new uint8_t[audio_encoder_buffer_size];

	// Add audio metadata (if any)
	for (std::map<std::string, std::string>::iterator iter = info.metadata.begin(); iter != info.metadata.end(); ++iter) {
		av_dict_set(&st->metadata, iter->first.c_str(), iter->second.c_str(), 0);
	}

	ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::open_audio", "audio_codec_ctx->thread_count", audio_codec_ctx->thread_count, "audio_input_frame_size", audio_input_frame_size, "buffer_size", AVCODEC_MAX_AUDIO_FRAME_SIZE + MY_INPUT_BUFFER_PADDING_SIZE);
}

// open video codec
void FFmpegWriter::open_video(AVFormatContext *oc, AVStream *st) {
	AVCodec *codec;
	AV_GET_CODEC_FROM_STREAM(st, video_codec_ctx)

	// Set number of threads equal to number of processors (not to exceed 16)
	video_codec_ctx->thread_count = std::min(FF_NUM_PROCESSORS, 16);

#if USE_HW_ACCEL
	if (hw_en_on && hw_en_supported) {
		//char *dev_hw = NULL;
		char adapter[256];
		char *adapter_ptr = NULL;
		int adapter_num;
		// Use the hw device given in the environment variable HW_EN_DEVICE_SET or the default if not set
		adapter_num = openshot::Settings::Instance()->HW_EN_DEVICE_SET;
		std::clog << "Encoding Device Nr: " << adapter_num << "\n";
		if (adapter_num < 3 && adapter_num >=0) {
#if defined(__linux__)
				snprintf(adapter,sizeof(adapter),"/dev/dri/renderD%d", adapter_num+128);
				// Maybe 127 is better because the first card would be 1?!
				adapter_ptr = adapter;
#elif defined(_WIN32) || defined(__APPLE__)
				adapter_ptr = NULL;
#endif
			}
			else {
				adapter_ptr = NULL; // Just to be sure
			}
// Check if it is there and writable
#if defined(__linux__)
		if( adapter_ptr != NULL && access( adapter_ptr, W_OK ) == 0 ) {
#elif defined(_WIN32) || defined(__APPLE__)
		if( adapter_ptr != NULL ) {
#endif
				ZmqLogger::Instance()->AppendDebugMethod("Encode Device present using device", "adapter", adapter_num);
		}
		else {
				adapter_ptr = NULL;  // use default
				ZmqLogger::Instance()->AppendDebugMethod("Encode Device not present, using default");
			}
		if (av_hwdevice_ctx_create(&hw_device_ctx, hw_en_av_device_type,
			adapter_ptr, NULL, 0) < 0) {
				ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::open_video ERROR creating hwdevice, Codec name:", info.vcodec.c_str(), -1);
				throw InvalidCodec("Could not create hwdevice", path);
		}
	}
#endif // USE_HW_ACCEL

	/* find the video encoder */
	codec = avcodec_find_encoder_by_name(info.vcodec.c_str());
	if (!codec)
		codec = avcodec_find_encoder(AV_FIND_DECODER_CODEC_ID(st));
	if (!codec)
		throw InvalidCodec("Could not find codec", path);

	/* Force max_b_frames to 0 in some cases (i.e. for mjpeg image sequences */
	if (video_codec_ctx->max_b_frames && video_codec_ctx->codec_id != AV_CODEC_ID_MPEG4 && video_codec_ctx->codec_id != AV_CODEC_ID_MPEG1VIDEO && video_codec_ctx->codec_id != AV_CODEC_ID_MPEG2VIDEO)
		video_codec_ctx->max_b_frames = 0;

	// Init options
	AVDictionary *opts = NULL;
	av_dict_set(&opts, "strict", "experimental", 0);

#if USE_HW_ACCEL
	if (hw_en_on && hw_en_supported) {
		video_codec_ctx->pix_fmt   = hw_en_av_pix_fmt;

		// for the list of possible options, see the list of codec-specific options:
		// e.g. ffmpeg -h encoder=h264_vaapi or ffmpeg -h encoder=hevc_vaapi
		// and "man ffmpeg-codecs"

		// For VAAPI, it is safer to explicitly set rc_mode instead of relying on auto-selection
		// which is ffmpeg version-specific.
		if (hw_en_av_pix_fmt == AV_PIX_FMT_VAAPI) {
			int64_t qp;
			if (av_opt_get_int(video_codec_ctx->priv_data, "qp", 0, &qp) != 0 || qp == 0) {
				// unless "qp" was set for CQP, switch to VBR RC mode
				av_opt_set(video_codec_ctx->priv_data, "rc_mode", "VBR", 0);

				// In the current state (ffmpeg-4.2-4 libva-mesa-driver-19.1.5-1) to use VBR,
				// one has to specify both bit_rate and maxrate, otherwise a small low quality file is generated on Intel iGPU).
				video_codec_ctx->rc_max_rate = video_codec_ctx->bit_rate;
			}
		}

		switch (video_codec_ctx->codec_id) {
			case AV_CODEC_ID_H264:
				video_codec_ctx->max_b_frames = 0;        // At least this GPU doesn't support b-frames
				video_codec_ctx->profile = FF_PROFILE_H264_BASELINE | FF_PROFILE_H264_CONSTRAINED;
				av_opt_set(video_codec_ctx->priv_data, "preset", "slow", 0);
				av_opt_set(video_codec_ctx->priv_data, "tune", "zerolatency", 0);
				av_opt_set(video_codec_ctx->priv_data, "vprofile", "baseline", AV_OPT_SEARCH_CHILDREN);
				break;
			case AV_CODEC_ID_HEVC:
				// tested to work with defaults
				break;
			case AV_CODEC_ID_VP9:
				// tested to work with defaults
				break;
			default:
				ZmqLogger::Instance()->AppendDebugMethod("No codec-specific options defined for this codec. HW encoding may fail",
					"codec_id", video_codec_ctx->codec_id);
				break;
		}

		// set hw_frames_ctx for encoder's AVCodecContext
		int err;
		if ((err = set_hwframe_ctx(video_codec_ctx, hw_device_ctx, info.width, info.height)) < 0) {
				ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::open_video (set_hwframe_ctx) ERROR faled to set hwframe context",
					"width", info.width, "height", info.height, av_err2string(err), -1);
		}
	}
#endif // USE_HW_ACCEL

	/* open the codec */
	if (avcodec_open2(video_codec_ctx, codec, &opts) < 0)
		throw InvalidCodec("Could not open video codec", path);
	AV_COPY_PARAMS_FROM_CONTEXT(st, video_codec_ctx);

	// Free options
	av_dict_free(&opts);

	// Add video metadata (if any)
	for (std::map<std::string, std::string>::iterator iter = info.metadata.begin(); iter != info.metadata.end(); ++iter) {
		av_dict_set(&st->metadata, iter->first.c_str(), iter->second.c_str(), 0);
	}

	ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::open_video", "video_codec_ctx->thread_count", video_codec_ctx->thread_count);

}

// write all queued frames' audio to the video file
void FFmpegWriter::write_audio_packets(bool is_final) {
    // Init audio buffers / variables
    int total_frame_samples = 0;
    int frame_position = 0;
    int channels_in_frame = 0;
    int sample_rate_in_frame = 0;
    int samples_in_frame = 0;
    ChannelLayout channel_layout_in_frame = LAYOUT_MONO; // default channel layout

    // Create a new array (to hold all S16 audio samples, for the current queued frames
    unsigned int all_queued_samples_size = sizeof(int16_t) * (queued_audio_frames.size() * AVCODEC_MAX_AUDIO_FRAME_SIZE);
    int16_t *all_queued_samples = (int16_t *) av_malloc(all_queued_samples_size);
    int16_t *all_resampled_samples = NULL;
    int16_t *final_samples_planar = NULL;
    int16_t *final_samples = NULL;

    // Loop through each queued audio frame
    while (!queued_audio_frames.empty()) {
        // Get front frame (from the queue)
        std::shared_ptr<Frame> frame = queued_audio_frames.front();

        // Get the audio details from this frame
        sample_rate_in_frame = frame->SampleRate();
        samples_in_frame = frame->GetAudioSamplesCount();
        channels_in_frame = frame->GetAudioChannelsCount();
        channel_layout_in_frame = frame->ChannelsLayout();

        // Get audio sample array
        float *frame_samples_float = NULL;
        // Get samples interleaved together (c1 c2 c1 c2 c1 c2)
        frame_samples_float = frame->GetInterleavedAudioSamples(sample_rate_in_frame, NULL, &samples_in_frame);

        // Calculate total samples
        total_frame_samples = samples_in_frame * channels_in_frame;

        // Translate audio sample values back to 16 bit integers with saturation
        const int16_t max16 = 32767;
        const int16_t min16 = -32768;
        for (int s = 0; s < total_frame_samples; s++, frame_position++) {
            float valF = frame_samples_float[s] * (1 << 15);
            int16_t conv;
            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
            all_queued_samples[frame_position] = conv;
        }

        // Deallocate float array
        delete[] frame_samples_float;

        // Remove front item
        queued_audio_frames.pop_front();

    } // end while


    // Update total samples (since we've combined all queued frames)
    total_frame_samples = frame_position;
    int remaining_frame_samples = total_frame_samples;
    int samples_position = 0;


    ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::write_audio_packets", "is_final", is_final, "total_frame_samples", total_frame_samples, "channel_layout_in_frame", channel_layout_in_frame, "channels_in_frame", channels_in_frame, "samples_in_frame", samples_in_frame, "LAYOUT_MONO", LAYOUT_MONO);

    // Keep track of the original sample format
    AVSampleFormat output_sample_fmt = audio_codec_ctx->sample_fmt;

    AVFrame *audio_frame = NULL;
    if (!is_final) {
        // Create input frame (and allocate arrays)
        audio_frame = AV_ALLOCATE_FRAME();
        AV_RESET_FRAME(audio_frame);
        audio_frame->nb_samples = total_frame_samples / channels_in_frame;

        // Fill input frame with sample data
        int error_code = avcodec_fill_audio_frame(audio_frame, channels_in_frame, AV_SAMPLE_FMT_S16, (uint8_t *) all_queued_samples, all_queued_samples_size, 0);
        if (error_code < 0) {
            ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::write_audio_packets ERROR [" + av_err2string(error_code) + "]", "error_code", error_code);
        }

        // Do not convert audio to planar format (yet). We need to keep everything interleaved at this point.
        switch (audio_codec_ctx->sample_fmt) {
            case AV_SAMPLE_FMT_FLTP: {
                output_sample_fmt = AV_SAMPLE_FMT_FLT;
                break;
            }
            case AV_SAMPLE_FMT_S32P: {
                output_sample_fmt = AV_SAMPLE_FMT_S32;
                break;
            }
            case AV_SAMPLE_FMT_S16P: {
                output_sample_fmt = AV_SAMPLE_FMT_S16;
                break;
            }
            case AV_SAMPLE_FMT_U8P: {
                output_sample_fmt = AV_SAMPLE_FMT_U8;
                break;
            }
            default: {
                // This is only here to silence unused-enum warnings
                break;
            }
        }

        // Update total samples & input frame size (due to bigger or smaller data types)
        total_frame_samples *= (float(info.sample_rate) / sample_rate_in_frame); // adjust for different byte sizes
        total_frame_samples *= (float(info.channels) / channels_in_frame); // adjust for different # of 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 / channels_in_frame;
        av_samples_alloc(audio_converted->data, audio_converted->linesize, info.channels, audio_converted->nb_samples, output_sample_fmt, 0);

        ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::write_audio_packets (1st resampling)", "in_sample_fmt", AV_SAMPLE_FMT_S16, "out_sample_fmt", output_sample_fmt, "in_sample_rate", sample_rate_in_frame, "out_sample_rate", info.sample_rate, "in_channels", channels_in_frame, "out_channels", info.channels);

        // 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", output_sample_fmt, 0); // planar not allowed here
            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
        int 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
        );

        // Set remaining samples
        remaining_frame_samples = total_frame_samples;

        // Create a new array (to hold all resampled S16 audio samples)
        all_resampled_samples = (int16_t *) av_malloc(
            sizeof(int16_t) * nb_samples * info.channels
            * (av_get_bytes_per_sample(output_sample_fmt) /
               av_get_bytes_per_sample(AV_SAMPLE_FMT_S16) )
        );

        // Copy audio samples over original samples
        memcpy(all_resampled_samples, audio_converted->data[0], nb_samples * info.channels * av_get_bytes_per_sample(output_sample_fmt));

        // Remove converted audio
        av_freep(&(audio_frame->data[0]));
        AV_FREE_FRAME(&audio_frame);
        av_freep(&audio_converted->data[0]);
        AV_FREE_FRAME(&audio_converted);
        all_queued_samples = NULL; // this array cleared with above call

        ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::write_audio_packets (Successfully completed 1st resampling)", "nb_samples", nb_samples, "remaining_frame_samples", remaining_frame_samples);
    }

    // Loop until no more samples
    while (remaining_frame_samples > 0 || is_final) {
        // Get remaining samples needed for this packet
        int remaining_packet_samples = (audio_input_frame_size * info.channels) - audio_input_position;

        // Determine how many samples we need
        int diff = 0;
        if (remaining_frame_samples >= remaining_packet_samples) {
            diff = remaining_packet_samples;
        } else {
            diff = remaining_frame_samples;
        }

        // Copy frame samples into the packet samples array
        if (!is_final)
            //TODO: Make this more sane
            memcpy(
                samples + (audio_input_position
                    * (av_get_bytes_per_sample(output_sample_fmt) /
                       av_get_bytes_per_sample(AV_SAMPLE_FMT_S16) )
                ),
                all_resampled_samples + samples_position,
                diff * av_get_bytes_per_sample(output_sample_fmt)
            );

        // Increment counters
        audio_input_position += diff;
        samples_position += diff * (av_get_bytes_per_sample(output_sample_fmt) / av_get_bytes_per_sample(AV_SAMPLE_FMT_S16));
        remaining_frame_samples -= diff;

        // Do we have enough samples to proceed?
        if (audio_input_position < (audio_input_frame_size * info.channels) && !is_final)
            // Not enough samples to encode... so wait until the next frame
            break;

        // Convert to planar (if needed by audio codec)
        AVFrame *frame_final = AV_ALLOCATE_FRAME();
        AV_RESET_FRAME(frame_final);
        if (av_sample_fmt_is_planar(audio_codec_ctx->sample_fmt)) {
            ZmqLogger::Instance()->AppendDebugMethod(
      "FFmpegWriter::write_audio_packets (2nd resampling for Planar formats)",
                "in_sample_fmt", output_sample_fmt,
                "out_sample_fmt", audio_codec_ctx->sample_fmt,
                "in_sample_rate", info.sample_rate,
                "out_sample_rate", info.sample_rate,
                "in_channels", info.channels,
                "out_channels", info.channels
            );

            // setup resample context
            if (!avr_planar) {
                avr_planar = SWR_ALLOC();
                av_opt_set_int(avr_planar, "in_channel_layout", info.channel_layout, 0);
                av_opt_set_int(avr_planar, "out_channel_layout", info.channel_layout, 0);
                av_opt_set_int(avr_planar, "in_sample_fmt", output_sample_fmt, 0);
                av_opt_set_int(avr_planar, "out_sample_fmt", audio_codec_ctx->sample_fmt, 0); // planar not allowed here
                av_opt_set_int(avr_planar, "in_sample_rate", info.sample_rate, 0);
                av_opt_set_int(avr_planar, "out_sample_rate", info.sample_rate, 0);
                av_opt_set_int(avr_planar, "in_channels", info.channels, 0);
                av_opt_set_int(avr_planar, "out_channels", info.channels, 0);
                SWR_INIT(avr_planar);
            }

            // Create input frame (and allocate arrays)
            audio_frame = AV_ALLOCATE_FRAME();
            AV_RESET_FRAME(audio_frame);
            audio_frame->nb_samples = audio_input_position / info.channels;

            // Create a new array
            final_samples_planar = (int16_t *) av_malloc(
                sizeof(int16_t) * audio_frame->nb_samples * info.channels
                * (av_get_bytes_per_sample(output_sample_fmt) /
                   av_get_bytes_per_sample(AV_SAMPLE_FMT_S16) )
            );

            // Copy audio into buffer for frame
            memcpy(final_samples_planar, samples, audio_frame->nb_samples * info.channels * av_get_bytes_per_sample(output_sample_fmt));

            // Fill input frame with sample data
            avcodec_fill_audio_frame(audio_frame, info.channels, output_sample_fmt,
                (uint8_t *) final_samples_planar, audio_encoder_buffer_size, 0);

            // Create output frame (and allocate arrays)
            frame_final->nb_samples = audio_input_frame_size;
            frame_final->channels = info.channels;
            frame_final->format = audio_codec_ctx->sample_fmt;
            frame_final->channel_layout = info.channel_layout;
            av_samples_alloc(frame_final->data, frame_final->linesize, info.channels,
                frame_final->nb_samples, audio_codec_ctx->sample_fmt, 0);

            // Convert audio samples
            int nb_samples = SWR_CONVERT(
                avr_planar,                  // audio resample context
                frame_final->data,           // output data pointers
                frame_final->linesize[0],    // output plane size, in bytes. (0 if unknown)
                frame_final->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
            );

            // Copy audio samples over original samples
            if (nb_samples > 0) {
                memcpy(samples, frame_final->data[0],
                    nb_samples * av_get_bytes_per_sample(audio_codec_ctx->sample_fmt) * info.channels);
            }

            // deallocate AVFrame
            av_freep(&(audio_frame->data[0]));
            AV_FREE_FRAME(&audio_frame);
            all_queued_samples = NULL; // this array cleared with above call

            ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::write_audio_packets (Successfully completed 2nd resampling for Planar formats)", "nb_samples", nb_samples);

        } else {
            // Create a new array
            final_samples = (int16_t *) av_malloc(
                sizeof(int16_t) * audio_input_position
                * (av_get_bytes_per_sample(audio_codec_ctx->sample_fmt) /
                   av_get_bytes_per_sample(AV_SAMPLE_FMT_S16) )
            );

            // Copy audio into buffer for frame
            memcpy(final_samples, samples,
                audio_input_position * av_get_bytes_per_sample(audio_codec_ctx->sample_fmt));

            // Init the nb_samples property
            frame_final->nb_samples = audio_input_frame_size;

            // Fill the final_frame AVFrame with audio (non planar)
            avcodec_fill_audio_frame(frame_final, audio_codec_ctx->channels,
                audio_codec_ctx->sample_fmt, (uint8_t *) final_samples,
                audio_encoder_buffer_size, 0);
        }

        // Set the AVFrame's PTS
        frame_final->pts = audio_timestamp;

        // Init the packet
        AVPacket pkt;
        av_init_packet(&pkt);
        pkt.data = audio_encoder_buffer;
        pkt.size = audio_encoder_buffer_size;

        // Set the packet's PTS prior to encoding
        pkt.pts = pkt.dts = audio_timestamp;

        /* encode the audio samples */
        int got_packet_ptr = 0;

#if IS_FFMPEG_3_2
        // Encode audio (latest version of FFmpeg)
        int error_code;
        int ret = 0;
        int frame_finished = 0;
        error_code = ret =  avcodec_send_frame(audio_codec_ctx, frame_final);
        if (ret < 0 && ret !=  AVERROR(EINVAL) && ret != AVERROR_EOF) {
            avcodec_send_frame(audio_codec_ctx, NULL);
        }
        else {
            if (ret >= 0)
                pkt.size = 0;
            ret =  avcodec_receive_packet(audio_codec_ctx, &pkt);
            if (ret >= 0)
                frame_finished = 1;
            if(ret == AVERROR(EINVAL) || ret == AVERROR_EOF) {
                avcodec_flush_buffers(audio_codec_ctx);
                ret = 0;
            }
            if (ret >= 0) {
                ret = frame_finished;
            }
        }
        if (!pkt.data && !frame_finished)
        {
            ret = -1;
        }
        got_packet_ptr = ret;
#else
        // Encode audio (older versions of FFmpeg)
        int error_code = avcodec_encode_audio2(audio_codec_ctx, &pkt, frame_final, &got_packet_ptr);
#endif
        /* if zero size, it means the image was buffered */
        if (error_code == 0 && got_packet_ptr) {

            // Since the PTS can change during encoding, set the value again.  This seems like a huge hack,
            // but it fixes lots of PTS related issues when I do this.
            pkt.pts = pkt.dts = audio_timestamp;

            // Scale the PTS to the audio stream timebase (which is sometimes different than the codec's timebase)
            av_packet_rescale_ts(&pkt, audio_codec_ctx->time_base, audio_st->time_base);

            // set stream
            pkt.stream_index = audio_st->index;
            pkt.flags |= AV_PKT_FLAG_KEY;

            /* write the compressed frame in the media file */
            error_code = av_interleaved_write_frame(oc, &pkt);
        }

        if (error_code < 0) {
            ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::write_audio_packets ERROR [" + av_err2string(error_code) + "]", "error_code", error_code);
        }

        // Increment PTS (no pkt.duration, so calculate with maths)
        audio_timestamp += FFMIN(audio_input_frame_size, audio_input_position);

        // deallocate AVFrame
        av_freep(&(frame_final->data[0]));
        AV_FREE_FRAME(&frame_final);

        // deallocate memory for packet
        AV_FREE_PACKET(&pkt);

        // Reset position
        audio_input_position = 0;
        is_final = false;
    }

    // Delete arrays (if needed)
    if (all_resampled_samples) {
        av_freep(&all_resampled_samples);
        all_resampled_samples = NULL;
    }
    if (all_queued_samples) {
        av_freep(&all_queued_samples);
        all_queued_samples = NULL;
    }
}

// Allocate an AVFrame object
AVFrame *FFmpegWriter::allocate_avframe(PixelFormat pix_fmt, int width, int height, int *buffer_size, uint8_t *new_buffer) {
	// Create an RGB AVFrame
	AVFrame *new_av_frame = NULL;

	// Allocate an AVFrame structure
	new_av_frame = AV_ALLOCATE_FRAME();
	if (new_av_frame == NULL)
		throw OutOfMemory("Could not allocate AVFrame", path);

	// Determine required buffer size and allocate buffer
	*buffer_size = AV_GET_IMAGE_SIZE(pix_fmt, width, height);

	// Create buffer (if not provided)
	if (!new_buffer) {
		// New Buffer
		new_buffer = (uint8_t *) av_malloc(*buffer_size * sizeof(uint8_t));
		// Attach buffer to AVFrame
		AV_COPY_PICTURE_DATA(new_av_frame, new_buffer, pix_fmt, width, height);
		new_av_frame->width = width;
		new_av_frame->height = height;
		new_av_frame->format = pix_fmt;
	}

	// return AVFrame
	return new_av_frame;
}

// process video frame
void FFmpegWriter::process_video_packet(std::shared_ptr<Frame> frame) {
	// Determine the height & width of the source image
	int source_image_width = frame->GetWidth();
	int source_image_height = frame->GetHeight();

	// Do nothing if size is 1x1 (i.e. no image in this frame)
	if (source_image_height == 1 && source_image_width == 1)
		return;

	// Init rescalers (if not initialized yet)
	if (image_rescalers.size() == 0)
		InitScalers(source_image_width, source_image_height);

	// Get a unique rescaler (for this thread)
	SwsContext *scaler = image_rescalers[rescaler_position];
	rescaler_position++;
	if (rescaler_position == num_of_rescalers)
		rescaler_position = 0;

    // Allocate an RGB frame & final output frame
    int bytes_source = 0;
    int bytes_final = 0;
    AVFrame *frame_source = NULL;
    const uchar *pixels = NULL;

    // Get a list of pixels from source image
    pixels = frame->GetPixels();

    // Init AVFrame for source image & final (converted image)
    frame_source = allocate_avframe(PIX_FMT_RGBA, source_image_width, source_image_height, &bytes_source, (uint8_t *) pixels);
#if IS_FFMPEG_3_2
    AVFrame *frame_final;
#if USE_HW_ACCEL
    if (hw_en_on && hw_en_supported) {
        frame_final = allocate_avframe(AV_PIX_FMT_NV12, info.width, info.height, &bytes_final, NULL);
    } else
#endif // USE_HW_ACCEL
    {
        frame_final = allocate_avframe(
            (AVPixelFormat)(video_st->codecpar->format),
            info.width, info.height, &bytes_final, NULL
        );
    }
#else
    AVFrame *frame_final = allocate_avframe(video_codec_ctx->pix_fmt, info.width, info.height, &bytes_final, NULL);
#endif // IS_FFMPEG_3_2

    // Fill with data
    AV_COPY_PICTURE_DATA(frame_source, (uint8_t *) pixels, PIX_FMT_RGBA, source_image_width, source_image_height);
    ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::process_video_packet", "frame->number", frame->number, "bytes_source", bytes_source, "bytes_final", bytes_final);

    // Resize & convert pixel format
    sws_scale(scaler, frame_source->data, frame_source->linesize, 0,
              source_image_height, frame_final->data, frame_final->linesize);

    // Add resized AVFrame to av_frames map
    add_avframe(frame, frame_final);

    // Deallocate memory
    AV_FREE_FRAME(&frame_source);
}

// write video frame
bool FFmpegWriter::write_video_packet(std::shared_ptr<Frame> frame, AVFrame *frame_final) {
#if (LIBAVFORMAT_VERSION_MAJOR >= 58)
	// FFmpeg 4.0+
	ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::write_video_packet",
		"frame->number", frame->number, "oc->oformat->flags", oc->oformat->flags);

	if (AV_GET_CODEC_TYPE(video_st) == AVMEDIA_TYPE_VIDEO && AV_FIND_DECODER_CODEC_ID(video_st) == AV_CODEC_ID_RAWVIDEO) {
#else
	ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::write_video_packet",
		"frame->number", frame->number,
		"oc->oformat->flags & AVFMT_RAWPICTURE", oc->oformat->flags & AVFMT_RAWPICTURE);

	if (oc->oformat->flags & AVFMT_RAWPICTURE) {
#endif
		// Raw video case.
		AVPacket pkt;
		av_init_packet(&pkt);

		pkt.flags |= AV_PKT_FLAG_KEY;
		pkt.stream_index = video_st->index;
		pkt.data = (uint8_t *) frame_final->data;
		pkt.size = sizeof(AVPicture);

		// Set PTS (in frames and scaled to the codec's timebase)
		pkt.pts = video_timestamp;

		/* write the compressed frame in the media file */
		int error_code = av_interleaved_write_frame(oc, &pkt);
		if (error_code < 0) {
			ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::write_video_packet ERROR [" + av_err2string(error_code) + "]", "error_code", error_code);
			return false;
		}

		// Deallocate packet
		AV_FREE_PACKET(&pkt);

	} else
	{

		AVPacket pkt;
		av_init_packet(&pkt);
		pkt.data = NULL;
		pkt.size = 0;
		pkt.pts = pkt.dts = AV_NOPTS_VALUE;

		// Assign the initial AVFrame PTS from the frame counter
		frame_final->pts = video_timestamp;
#if USE_HW_ACCEL
		if (hw_en_on && hw_en_supported) {
			if (!(hw_frame = av_frame_alloc())) {
				std::clog << "Error code: av_hwframe_alloc\n";
			}
			if (av_hwframe_get_buffer(video_codec_ctx->hw_frames_ctx, hw_frame, 0) < 0) {
				std::clog << "Error code: av_hwframe_get_buffer\n";
			}
			if (!hw_frame->hw_frames_ctx) {
				std::clog << "Error hw_frames_ctx.\n";
			}
			hw_frame->format = AV_PIX_FMT_NV12;
			if ( av_hwframe_transfer_data(hw_frame, frame_final, 0) < 0) {
				std::clog << "Error while transferring frame data to surface.\n";
			}
			av_frame_copy_props(hw_frame, frame_final);
		}
#endif // USE_HW_ACCEL
		/* encode the image */
		int got_packet_ptr = 0;
		int error_code = 0;
#if IS_FFMPEG_3_2
		// Write video packet (latest version of FFmpeg)
		int ret;

	#if USE_HW_ACCEL
		if (hw_en_on && hw_en_supported) {
			ret = avcodec_send_frame(video_codec_ctx, hw_frame); //hw_frame!!!
		} else
	#endif // USE_HW_ACCEL
		{
			ret = avcodec_send_frame(video_codec_ctx, frame_final);
		}
		error_code = ret;
		if (ret < 0 ) {
			ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::write_video_packet (Frame not sent)");
			if (ret == AVERROR(EAGAIN) ) {
				std::clog << "Frame EAGAIN\n";
			}
			if (ret == AVERROR_EOF ) {
				std::clog << "Frame AVERROR_EOF\n";
			}
			avcodec_send_frame(video_codec_ctx, NULL);
		}
		else {
			while (ret >= 0) {
				ret = avcodec_receive_packet(video_codec_ctx, &pkt);

				if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
					avcodec_flush_buffers(video_codec_ctx);
					got_packet_ptr = 0;
					break;
				}
				if (ret == 0) {
					got_packet_ptr = 1;
					break;
				}
			}
		}
#else
		// Write video packet (older than FFmpeg 3.2)
		error_code = avcodec_encode_video2(video_codec_ctx, &pkt, frame_final, &got_packet_ptr);
		if (error_code != 0) {
			ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::write_video_packet ERROR [" + av_err2string(error_code) + "]", "error_code", error_code);
		}
		if (got_packet_ptr == 0) {
			ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::write_video_packet (Frame gotpacket error)");
		}
#endif // IS_FFMPEG_3_2

		/* if zero size, it means the image was buffered */
		if (error_code == 0 && got_packet_ptr) {
			// set the timestamp
            av_packet_rescale_ts(&pkt, video_codec_ctx->time_base, video_st->time_base);
			pkt.stream_index = video_st->index;

			/* write the compressed frame in the media file */
			int result = av_interleaved_write_frame(oc, &pkt);
			if (result < 0) {
				ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::write_video_packet ERROR [" + av_err2string(result) + "]", "result", result);
				return false;
			}
		}

		// Deallocate packet
		AV_FREE_PACKET(&pkt);
#if USE_HW_ACCEL
		if (hw_en_on && hw_en_supported) {
			if (hw_frame) {
				av_frame_free(&hw_frame);
				hw_frame = NULL;
			}
		}
#endif // USE_HW_ACCEL
	}

    // Increment PTS (in frames and scaled to the codec's timebase)
    video_timestamp += av_rescale_q(1, av_make_q(info.fps.den, info.fps.num), video_codec_ctx->time_base);

	// Success
	return true;
}

// Output the ffmpeg info about this format, streams, and codecs (i.e. dump format)
void FFmpegWriter::OutputStreamInfo() {
	// output debug info
	av_dump_format(oc, 0, path.c_str(), 1);
}

// Init a collection of software rescalers (thread safe)
void FFmpegWriter::InitScalers(int source_width, int source_height) {
	int scale_mode = SWS_FAST_BILINEAR;
	if (openshot::Settings::Instance()->HIGH_QUALITY_SCALING) {
		scale_mode = SWS_BICUBIC;
	}

	// Init software rescalers vector (many of them, one for each thread)
	for (int x = 0; x < num_of_rescalers; x++) {
		// Init the software scaler from FFMpeg
#if USE_HW_ACCEL
		if (hw_en_on && hw_en_supported) {
			img_convert_ctx = sws_getContext(source_width, source_height, PIX_FMT_RGBA,
				info.width, info.height, AV_PIX_FMT_NV12, scale_mode, NULL, NULL, NULL);
		} else
#endif // USE_HW_ACCEL
		{
			img_convert_ctx = sws_getContext(source_width, source_height, PIX_FMT_RGBA,
				info.width, info.height, AV_GET_CODEC_PIXEL_FORMAT(video_st, video_st->codec),
				scale_mode, NULL, NULL, NULL);
		}

		// Add rescaler to vector
		image_rescalers.push_back(img_convert_ctx);
	}
}

// Set audio resample options
void FFmpegWriter::ResampleAudio(int sample_rate, int channels) {
	original_sample_rate = sample_rate;
	original_channels = channels;
}

// Remove & deallocate all software scalers
void FFmpegWriter::RemoveScalers() {
	// Close all rescalers
	for (int x = 0; x < num_of_rescalers; x++)
		sws_freeContext(image_rescalers[x]);

	// Clear vector
	image_rescalers.clear();
}
