/**
 * @file   video_compress/libavcodec.cpp
 * @author Martin Pulec     <pulec@cesnet.cz>
 */
/*
 * Copyright (c) 2013-2020 CESNET, z. s. p. o.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, is permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * 3. Neither the name of CESNET nor the names of its contributors may be
 *    used to endorse or promote products derived from this software without
 *    specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING,
 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
 * EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#define __STDC_CONSTANT_MACROS

#ifdef HAVE_CONFIG_H
#include "config.h"
#include "config_unix.h"
#include "config_win32.h"
#endif // HAVE_CONFIG_H

#include "libavcodec_common.h"

#include <array>
#include <cassert>
#include <cmath>
#include <list>
#include <map>
#include <regex>
#include <stdexcept>
#include <string>
#include <thread>
#include <unordered_map>
#include <vector>

#include "debug.h"
#include "host.h"
#include "lib_common.h"
#include "messaging.h"
#include "module.h"
#include "rang.hpp"
#include "utils/misc.h"
#include "utils/resource_manager.h"
#include "utils/worker.h"
#include "video.h"
#include "video_compress.h"

#ifdef HWACC_VAAPI
extern "C"
{
#include <libavutil/hwcontext.h>
#include <libavutil/hwcontext_vaapi.h>
#include <libavcodec/vaapi.h>
}
#include "hwaccel_libav_common.h"
#endif

#ifdef HAVE_SWSCALE
extern "C"{
#include <libswscale/swscale.h>
}
#endif

#define MOD_NAME "[lavc] "

using namespace std;
using namespace std::string_literals;
using namespace rang;

static constexpr const codec_t DEFAULT_CODEC = MJPG;
static constexpr double DEFAULT_X264_X265_CRF = 22.0;
static constexpr const int DEFAULT_GOP_SIZE = 20;
static constexpr const char *DEFAULT_THREAD_MODE = "slice";

namespace {

struct setparam_param {
        double fps;
        bool interlaced;
        bool no_periodic_intra;
        int conv_thread_count; ///< number of threads used for UG conversions
        string thread_mode;
};

constexpr const char *DEFAULT_NVENC_PRESET = "p7";
constexpr const char *DEFAULT_NVENC_RC = "cbr";
constexpr const char *DEFAULT_NVENC_TUNE = "ull";
constexpr const char *FALLBACK_NVENC_PRESET = "llhq";

static constexpr const char *DEFAULT_QSV_PRESET = "medium";

typedef struct {
        const char *(*get_prefered_encoder)(bool is_rgb); ///< can be nullptr
        double avg_bpp;
        string (*get_preset)(string const & enc_name, int width, int height, double fps);
        void (*set_param)(AVCodecContext *, struct setparam_param *);
        int capabilities_priority;
} codec_params_t;

static string get_h264_h265_preset(string const & enc_name, int width, int height, double fps);
static void libavcodec_check_messages(struct state_video_compress_libav *s);
static void libavcodec_compress_done(struct module *mod);
static void setparam_default(AVCodecContext *, struct setparam_param *);
static void setparam_h264_h265_av1(AVCodecContext *, struct setparam_param *);
static void setparam_jpeg(AVCodecContext *, struct setparam_param *);
static void setparam_vp8_vp9(AVCodecContext *, struct setparam_param *);
static void set_thread_mode(AVCodecContext *codec_ctx, struct setparam_param *param);

typedef void (*pixfmt_callback_t)(AVFrame *out_frame, unsigned char *in_data, int width, int height);
static pixfmt_callback_t select_pixfmt_callback(AVPixelFormat fmt, codec_t src);
static void show_encoder_help(string const &name);
static void print_codec_supp_pix_fmts(const enum AVPixelFormat *first);
static void usage(void);
static int parse_fmt(struct state_video_compress_libav *s, char *fmt);
static void cleanup(struct state_video_compress_libav *s);

static unordered_map<codec_t, codec_params_t, hash<int>> codec_params = {
        { H264, codec_params_t{
                [](bool is_rgb) { return is_rgb ? "libx264rgb" : "libx264"; },
                0.07 * 2 /* for H.264: 1 - low motion, 2 - medium motion, 4 - high motion */
                * 2, // take into consideration that our H.264 is less effective due to specific preset/tune
                     // note - not used for libx264, which uses CRF by default
                get_h264_h265_preset,
                setparam_h264_h265_av1,
                100
        }},
        { H265, codec_params_t{
                [](bool) { return "libx265"; },
                0.04 * 2 * 2, // note - not used for libx265, which uses CRF by default
                get_h264_h265_preset,
                setparam_h264_h265_av1,
                101
        }},
        { MJPG, codec_params_t{
                nullptr,
                1.2,
                nullptr,
                setparam_jpeg,
                102
        }},
        { J2K, codec_params_t{
                nullptr,
                1.0,
                nullptr,
                setparam_default,
                500
        }},
        { VP8, codec_params_t{
                nullptr,
                0.4,
                nullptr,
                setparam_vp8_vp9,
                103
        }},
        { VP9, codec_params_t{
                nullptr,
                0.4,
                nullptr,
                setparam_vp8_vp9,
                104
        }},
        { HFYU, codec_params_t{
                nullptr,
                0,
                nullptr,
                setparam_default,
                501
        }},
        { FFV1, codec_params_t{
                nullptr,
                0,
                nullptr,
                setparam_default,
                502
        }},
        { AV1, codec_params_t{
                nullptr,
                0,
                nullptr,
                setparam_h264_h265_av1,
                600
        }},
};

struct state_video_compress_libav {
        struct module       module_data;

        pthread_mutex_t    *lavcd_global_lock;

        struct video_desc   saved_desc;

        AVFrame            *in_frame;
        // for every core - parts of the above
        AVFrame           **in_frame_part;
        AVCodecContext     *codec_ctx;

        unsigned char      *decoded; ///< intermediate representation for codecs
                                     ///< that are not directly supported
        codec_t             decoded_codec;
        decoder_t           decoder;

        codec_t             requested_codec_id;
        long long int       requested_bitrate;
        double              requested_bpp;
        double              requested_crf;
        int                 requested_cqp;
        // may be 422, 420 or 0 (no subsampling explicitly requested
        int                 requested_subsampling;
        // contains format that is supplied by UG to the encoder or swscale (if used)
        AVPixelFormat       selected_pixfmt;

        codec_t             out_codec;

        struct video_desc compressed_desc;

        struct setparam_param params;
        string              backend;
        int                 requested_gop;

        map<string, string> lavc_opts; ///< user-supplied options from command-line

        bool hwenc;
        AVFrame *hwframe;

#ifdef HAVE_SWSCALE
        struct SwsContext *sws_ctx;
		// contains format that is supplied to the encoder
        AVPixelFormat out_pixfmt;
        AVFrame *sws_frame;
#endif
};

struct codec_encoders_decoders{
        std::vector<std::string> encoders;
        std::vector<std::string> decoders;
};

static codec_encoders_decoders get_codec_encoders_decoders(AVCodecID id){
        codec_encoders_decoders res;
#if LIBAVCODEC_VERSION_INT > AV_VERSION_INT(58, 9, 100)
        const AVCodec *codec = nullptr;
        void *i = 0;
        while ((codec = av_codec_iterate(&i))) {
                if (av_codec_is_encoder(codec) && codec->id == id) {
                        res.encoders.emplace_back(codec->name);
                }
                if (av_codec_is_decoder(codec) && codec->id == id) {
                        res.decoders.emplace_back(codec->name);
                }
        }
#elif LIBAVCODEC_VERSION_MAJOR >= 54
        const AVCodec *codec = nullptr;
        if ((codec = avcodec_find_encoder(id))) {
                do {
                        if (av_codec_is_encoder(codec) && codec->id == id) {
                                res.encoders.emplace_back(codec->name);
                        }
                } while ((codec = av_codec_next(codec)));
        }

        if ((codec = avcodec_find_decoder(id))) {
                do {
                        if (av_codec_is_decoder(codec) && codec->id == id) {
                                res.decoders.emplace_back(codec->name);
                        }
                } while ((codec = av_codec_next(codec)));
        }
#else
        UNUSED(id);
#endif

        return res;
}

static void print_codec_info(AVCodecID id, char *buf, size_t buflen)
{
        auto info = get_codec_encoders_decoders(id);
        assert(buflen > 0);
        buf[0] = '\0';
        if(info.encoders.empty() && info.decoders.empty())
                return;

        strncat(buf, " (", buflen - strlen(buf) - 1);
        if (!info.encoders.empty()) {
                strncat(buf, "encoders:", buflen - strlen(buf) - 1);
                for(const auto& enc : info.encoders){
                        strncat(buf, " ", buflen - strlen(buf) - 1);
                        strncat(buf, enc.c_str(), buflen - strlen(buf) - 1);
                }
        }
        if (!info.decoders.empty()) {
                if (!info.encoders.empty()) {
                        strncat(buf, ", ", buflen - strlen(buf) - 1);
                }
                strncat(buf, "decoders:", buflen - strlen(buf) - 1);

                for(const auto& dec : info.decoders){
                        strncat(buf, " ", buflen - strlen(buf) - 1);
                        strncat(buf, dec.c_str(), buflen - strlen(buf) - 1);
                }
        }
        strncat(buf, ")", buflen - strlen(buf) - 1);
}

static void usage() {
        printf("Libavcodec encoder usage:\n");
        cout << style::bold << fg::red << "\t-c libavcodec" << fg::reset << "[:codec=<codec_name>|:encoder=<encoder>][:bitrate=<bits_per_sec>|:bpp=<bits_per_pixel>][:crf=<crf>|:cqp=<cqp>]"
                        "[:subsampling=<subsampling>][:gop=<gop>]"
                        "[:disable_intra_refresh][:threads=<thr_mode>][:<lavc_opt>=<val>]*\n" <<
                        style::reset;
        cout << style::bold << "\t\t<encoder>" << style::reset << " specifies encoder (eg. nvenc or libx264 for H.264)\n";
        cout << style::bold << "\t\t<codec_name>" << style::reset << " may be specified codec name (default MJPEG), supported codecs:\n";
        for (auto && param : codec_params) {
                enum AVCodecID avID = get_ug_to_av_codec(param.first);
                if (avID == AV_CODEC_ID_NONE) { // old FFMPEG -> codec id is flushed to 0 in compat
                        continue;
                }
                char avail[1024];
                const AVCodec *codec;
                if ((codec = avcodec_find_encoder(avID))) {
                        strcpy(avail, "available");
                } else {
                        strcpy(avail, "not available");
                }
                print_codec_info(avID, avail + strlen(avail), sizeof avail - strlen(avail));

                cout << "\t\t\t" << style::bold << get_codec_name(param.first) << style::reset << " - " << avail << "\n";

        }
        cout << style::bold << "\t\tdisable_intra_refresh" << style::reset << " - do not use Periodic Intra Refresh (H.264/H.265)\n";
        cout << style::bold << "\t\t<bits_per_sec>" << style::reset << " specifies requested bitrate\n"
                << "\t\t\t0 means codec default (same as when parameter omitted)\n";
        cout << style::bold << "\t\t<bits_per_pixel>" << style::reset << " specifies requested bitrate using compressed bits per pixel\n"
                << "\t\t\tbitrate = frame width * frame height * bits_per_pixel * fps\n";
        cout << style::bold << "\t\t<crf>" << style::reset << " specifies CRF factor (only for libx264/libx265)\n";
        cout << style::bold << "\t\t<subsampling" << style::reset << "> may be one of 444, 422, or 420, default 420 for progresive, 422 for interlaced\n";
        cout << style::bold << "\t\t<thr_mode>" << style::reset << " can be one of \"no\", \"frame\", \"slice\" or a number (of slice threads)\n";
        cout << style::bold << "\t\t<gop>" << style::reset << " specifies GOP size\n";
        cout << style::bold << "\t\t<lavc_opt>" << style::reset << " arbitrary option to be passed directly to libavcodec (eg. preset=veryfast), eventual colons must be backslash-escaped (eg. for x264opts)\n";
        cout << "\tUse '" << style::bold << "-c libavcodec:encoder=<enc>:help" << style::reset << "' to display encoder specific options.\n";
        cout << "\n";
        cout << "Libavcodec version (linked): " << style::bold << LIBAVCODEC_IDENT << style::reset << "\n";
        const char *swscale = "no";
#ifdef HAVE_SWSCALE
        swscale = "yes";
#endif
        cout << "Libswscale supported: " << style::bold << swscale << style::reset << "\n";
}

static int parse_fmt(struct state_video_compress_libav *s, char *fmt) {
        if (!fmt) {
                return 0;
        }

        bool show_help = false;

        // replace all '\:' with 2xDEL
        replace_all(fmt, ESCAPED_COLON, DELDEL);
        char *item, *save_ptr = NULL;

        while ((item = strtok_r(fmt, ":", &save_ptr)) != NULL) {
                if(strncasecmp("help", item, strlen("help")) == 0) {
                        show_help = true;
                } else if(strncasecmp("codec=", item, strlen("codec=")) == 0) {
                        char *codec = item + strlen("codec=");
                        s->requested_codec_id = get_codec_from_name(codec);
                        if (s->requested_codec_id == VIDEO_CODEC_NONE) {
                                log_msg(LOG_LEVEL_ERROR, "[lavc] Unable to find codec: \"%s\"\n", codec);
                                return -1;
                        }
                } else if(strncasecmp("bitrate=", item, strlen("bitrate=")) == 0) {
                        char *bitrate_str = item + strlen("bitrate=");
                        s->requested_bitrate = unit_evaluate(bitrate_str);
                        assert(s->requested_bitrate >= 0);
                } else if(strncasecmp("bpp=", item, strlen("bpp=")) == 0) {
                        char *bpp_str = item + strlen("bpp=");
                        s->requested_bpp = unit_evaluate_dbl(bpp_str);
                        assert(!std::isnan(s->requested_bpp));
                } else if(strncasecmp("crf=", item, strlen("crf=")) == 0) {
                        char *crf_str = item + strlen("crf=");
                        s->requested_crf = atof(crf_str);
                } else if(strncasecmp("cqp=", item, strlen("cqp=")) == 0) {
                        char *cqp_str = item + strlen("cqp=");
                        s->requested_cqp = atoi(cqp_str);
                } else if(strncasecmp("subsampling=", item, strlen("subsampling=")) == 0) {
                        char *subsample_str = item + strlen("subsampling=");
                        s->requested_subsampling = atoi(subsample_str);
                        if (s->requested_subsampling != 444 &&
                                        s->requested_subsampling != 422 &&
                                        s->requested_subsampling != 420) {
                                log_msg(LOG_LEVEL_ERROR, "[lavc] Supported subsampling is 444, 422, or 420.\n");
                                return -1;
                        }
                } else if (strcasecmp("disable_intra_refresh", item) == 0) {
                        s->params.no_periodic_intra = true;
                } else if(strncasecmp("threads=", item, strlen("threads=")) == 0) {
                        char *threads = item + strlen("threads=");
                        s->params.thread_mode = threads;
                } else if(strncasecmp("encoder=", item, strlen("encoder=")) == 0) {
                        char *backend = item + strlen("encoder=");
                        s->backend = backend;
                } else if(strncasecmp("gop=", item, strlen("gop=")) == 0) {
                        char *gop = item + strlen("gop=");
                        s->requested_gop = atoi(gop);
                } else if (strchr(item, '=')) {
                        char *c_val_dup = strdup(strchr(item, '=') + 1);
                        replace_all(c_val_dup, DELDEL, ":");
                        string key, val;
                        key = string(item, strchr(item, '='));
                        s->lavc_opts[key] = c_val_dup;
                        free(c_val_dup);
                } else {
                        log_msg(LOG_LEVEL_ERROR, "[lavc] Error: unknown option %s.\n",
                                        item);
                        return -1;
                }
                fmt = NULL;
        }

        if (show_help) {
                if (s->backend.empty()) {
                        usage();
                } else {
                        show_encoder_help(s->backend);
                }
        }

        if ((get_commandline_param("lavc-use-codec") != nullptr && "help"s == get_commandline_param("lavc-use-codec")) ||
                        (show_help && !s->backend.empty())) {
                auto *codec = avcodec_find_encoder_by_name(s->backend.c_str());
                if (codec != nullptr) {
                        cout << "\n";
                        print_codec_supp_pix_fmts(codec->pix_fmts);
                } else {
                        LOG(LOG_LEVEL_ERROR) << MOD_NAME << "Cannot open encoder: " << s->backend << "\n";
                }
        }

        if (show_help || (get_commandline_param("lavc-use-codec") != nullptr && "help"s == get_commandline_param("lavc-use-codec"))) {
                return 1;
        }

        return 0;
}

static list<compress_preset> get_libavcodec_presets() {
        list<compress_preset> ret;
#if LIBAVCODEC_VERSION_INT <= AV_VERSION_INT(58, 9, 100)
        avcodec_register_all();
#endif

        pthread_mutex_t *lavcd_global_lock = rm_acquire_shared_lock(LAVCD_LOCK_NAME);
        pthread_mutex_lock(lavcd_global_lock);

        if (avcodec_find_encoder_by_name("libx264")) {
                ret.push_back({"encoder=libx264:bpp=0.096", 20, [](const struct video_desc *d){return (long)(d->width * d->height * d->fps * 0.096);}, {25, 1.5, 0}, {15, 1, 0}});
                ret.push_back({"encoder=libx264:bpp=0.193", 30, [](const struct video_desc *d){return (long)(d->width * d->height * d->fps * 0.193);}, {28, 1.5, 0}, {20, 1, 0}});
                ret.push_back({"encoder=libx264:bpp=0.289", 50, [](const struct video_desc *d){return (long)(d->width * d->height * d->fps * 0.289);}, {30, 1.5, 0}, {25, 1, 0}});
        }
        // NVENC and MJPEG are disabled in order not to be chosen by CoUniverse.
        // Enable if needed (also possible to add H.265 etc).
#if 0
        AVCodec *codec;
        if ((codec = avcodec_find_encoder_by_name("nvenc_h264"))) {
                AVCodecContext *codec_ctx = avcodec_alloc_context3(codec);
                assert(codec_ctx);
                codec_ctx->pix_fmt = AV_PIX_FMT_NV12;
                codec_ctx->width = 1920;
                codec_ctx->height = 1080;
                if (avcodec_open2(codec_ctx, codec, NULL) == 0) {
                        ret.push_back({"encoder=nvenc_h264:bpp=0.096", 20, [](const struct video_desc *d){return (long)(d->width * d->height * d->fps * 0.096);}, {25, 0, 0.2}, {15, 1, 0}});
                        ret.push_back({"encoder=nvenc_h264:bpp=0.193", 30, [](const struct video_desc *d){return (long)(d->width * d->height * d->fps * 0.193);}, {28, 0, 0.2}, {20, 1, 0}});
                        ret.push_back({"encoder=nvenc_h264:bitrate=0.289", 50, [](const struct video_desc *d){return (long)(d->width * d->height * d->fps * 0.289);}, {30, 0, 0.2}, {25, 1, 0}});
                        avcodec_close(codec_ctx);
                }
                av_free(codec_ctx);
        }
#endif
#if 0
        ret.push_back({ "codec=MJPEG", 35, 50*1000*1000, {20, 0.75, 0}, {10, 0.5, 0}});
#endif

        pthread_mutex_unlock(lavcd_global_lock);
        rm_release_shared_lock(LAVCD_LOCK_NAME);

        return ret;
}

static compress_module_info get_libavcodec_module_info(){
        compress_module_info module_info;
        module_info.name = "libavcodec";
        module_info.opts.emplace_back(module_option{"Bitrate", "Bitrate", "quality", ":bitrate=", false});
        module_info.opts.emplace_back(module_option{"Crf", "specifies CRF factor (only for libx264/libx265)", "crf", ":crf=", false});
        module_info.opts.emplace_back(module_option{"Disable intra refresh",
                        "Do not use Periodic Intra Refresh (H.264/H.265)",
                        "disable_intra_refresh", ":disable_intra_refresh", true});
        module_info.opts.emplace_back(module_option{"Subsampling",
                        "may be one of 444, 422, or 420, default 420 for progresive, 422 for interlaced",
                        "subsampling", ":subsampling=", false});
        module_info.opts.emplace_back(module_option{"Lavc opt",
                        "arbitrary option to be passed directly to libavcodec (eg. preset=veryfast), eventual colons must be backslash-escaped (eg. for x264opts)",
                        "lavc_opt", ":", false});

        for (const auto& param : codec_params) {
                enum AVCodecID avID = get_ug_to_av_codec(param.first);
                if (avID == AV_CODEC_ID_NONE) { // old FFMPEG -> codec id is flushed to 0 in compat
                        continue;
                }
                const AVCodec *i;
                if (!(i = avcodec_find_encoder(avID))) {
                        continue;
                }

                codec codec_info;
                codec_info.name = get_codec_name(param.first);
                codec_info.priority = param.second.capabilities_priority;
                codec_info.encoders.emplace_back(
                                encoder{"default", ":codec=" + codec_info.name});

                auto coders = get_codec_encoders_decoders(avID);
                for(const auto& enc : coders.encoders){
                        codec_info.encoders.emplace_back(
                                        encoder{enc, ":encoder=" + enc});
                }

                module_info.codecs.emplace_back(std::move(codec_info));
        }

        return module_info;
}

struct module * libavcodec_compress_init(struct module *parent, const char *opts)
{
        struct state_video_compress_libav *s;

        s = new state_video_compress_libav();
        s->lavcd_global_lock = rm_acquire_shared_lock(LAVCD_LOCK_NAME);
        av_log_set_level((log_level - 1) * 8);
#if LIBAVCODEC_VERSION_INT <= AV_VERSION_INT(58, 9, 100)
        /*  register all the codecs (you can also register only the codec
         *         you wish to have smaller code */
        avcodec_register_all();
#endif

        s->codec_ctx = NULL;
        s->in_frame = NULL;
        s->requested_codec_id = VIDEO_CODEC_NONE;
        s->requested_subsampling = 0;
        s->params.thread_mode = DEFAULT_THREAD_MODE;
        // both following options take 0 as a valid argument, so we use -1 as an implicit value
        s->requested_crf = -1;
        s->requested_cqp = -1;

        memset(&s->saved_desc, 0, sizeof(s->saved_desc));

        char *fmt = strdup(opts);
        int ret = parse_fmt(s, fmt);
        free(fmt);
        if(ret != 0) {
                delete s;
                if(ret > 0)
                        return &compress_init_noerr;
                else
                        return NULL;
        }

        try {
                s->params.conv_thread_count = stoi(s->params.thread_mode);
        } catch(invalid_argument &) { // thread mode is not a number of threads (eg. slice)
                s->params.conv_thread_count = min<unsigned int>(thread::hardware_concurrency(), INT_MAX);
        }
        if (s->params.conv_thread_count < 1) {
                log_msg(LOG_LEVEL_WARNING, "Warning: Cannot get number of CPU cores!\n");
                s->params.conv_thread_count = 1;
        }
        s->in_frame_part = static_cast<AVFrame **>(calloc(s->params.conv_thread_count, sizeof(AVFrame *)));
        for(int i = 0; i < s->params.conv_thread_count; i++) {
                s->in_frame_part[i] = av_frame_alloc();
        }

        s->decoded = NULL;

        module_init_default(&s->module_data);
        s->module_data.cls = MODULE_CLASS_DATA;
        s->module_data.priv_data = s;
        s->module_data.deleter = libavcodec_compress_done;
        module_register(&s->module_data, parent);

        s->hwenc = false;
        s->hwframe = NULL;

#ifdef HAVE_SWSCALE
        s->sws_ctx = nullptr;
        s->out_pixfmt = AV_PIX_FMT_NONE;
        s->sws_frame = nullptr;
#endif

        return &s->module_data;
}

#ifdef HWACC_VAAPI
static int vaapi_init(struct AVCodecContext *s){

        int pool_size = 20; //Default in ffmpeg examples

        AVBufferRef *device_ref = nullptr;
        AVBufferRef *hw_frames_ctx = nullptr;
        int ret = create_hw_device_ctx(AV_HWDEVICE_TYPE_VAAPI, &device_ref);
        if(ret < 0)
                goto fail;

        if (s->active_thread_type & FF_THREAD_FRAME)
                pool_size += s->thread_count;

        ret = create_hw_frame_ctx(device_ref,
                        s->width,
                        s->height,
                        AV_PIX_FMT_VAAPI,
                        AV_PIX_FMT_NV12,
                        pool_size,
                        &hw_frames_ctx);
        if(ret < 0)
                goto fail;

        s->hw_frames_ctx = hw_frames_ctx;

        av_buffer_unref(&device_ref);
        return 0;

fail:
        av_buffer_unref(&hw_frames_ctx);
        av_buffer_unref(&device_ref);
        return ret;
}
#endif

void print_codec_supp_pix_fmts(const enum AVPixelFormat *first) {
        string out;
        if (first == nullptr) {
                out += " (none)";
        }
        const enum AVPixelFormat *it = first;
        while (it != nullptr && *it != AV_PIX_FMT_NONE) {
                out += " "s + av_get_pix_fmt_name(*it++);
        }
        cerr << style::bold << MOD_NAME "Codec supported pixel formats:" << style::reset << out << "\n";
}

void print_pix_fmts(const list<enum AVPixelFormat>
                &req_pix_fmts, const enum AVPixelFormat *first) {
        print_codec_supp_pix_fmts(first);
        string out;
        for (auto &c : req_pix_fmts) {
                out += " "s + av_get_pix_fmt_name(c);
        }
        cerr << style::bold << MOD_NAME "Usable pixel formats:" << style::reset << out << "\n";
}

/**
 * Finds best pixel format
 *
 * Iterates over formats in req_pix_fmts and tries to find the same format in
 * second list, codec_pix_fmts. If found, returns that format. Efectivelly
 * select first match of item from first list in second list.
 *
 * @note
 * Unusable pixel formats and a currently selected one are removed from
 * req_pix_fmts.
 */
static enum AVPixelFormat get_first_matching_pix_fmt(list<enum AVPixelFormat>
                &req_pix_fmts, const enum AVPixelFormat *codec_pix_fmts)
{
        if(codec_pix_fmts == NULL)
                return AV_PIX_FMT_NONE;

        for (auto it = req_pix_fmts.begin(); it != req_pix_fmts.end(); ) {
                const enum AVPixelFormat *tmp = codec_pix_fmts;
                enum AVPixelFormat fmt;
                while((fmt = *tmp++) != AV_PIX_FMT_NONE) {
                        if (fmt == *it) {
                                enum AVPixelFormat ret = *it;
                                req_pix_fmts.erase(it);
                                return ret;
                        }
                }
                it = req_pix_fmts.erase(it);
        }

        return AV_PIX_FMT_NONE;
}

bool set_codec_ctx_params(struct state_video_compress_libav *s, AVPixelFormat pix_fmt, struct video_desc desc, codec_t ug_codec)
{
        bool is_x264_x265 = strncmp(s->codec_ctx->codec->name, "libx264", strlen("libx264")) == 0 ||
                strcmp(s->codec_ctx->codec->name, "libx265") == 0;

        double avg_bpp; // average bit per pixel
        avg_bpp = s->requested_bpp > 0.0 ? s->requested_bpp :
                codec_params[ug_codec].avg_bpp;

        int_fast64_t bitrate = s->requested_bitrate > 0 ? s->requested_bitrate :
                desc.width * desc.height * avg_bpp * desc.fps;

        bool have_preset = s->lavc_opts.find("preset") != s->lavc_opts.end();

        s->codec_ctx->strict_std_compliance = -2;

        // set bitrate
        if ((s->requested_bitrate > 0 || s->requested_bpp > 0.0)
                        || (!is_x264_x265 && s->requested_crf == -1 && s->requested_cqp == -1)) {
                s->codec_ctx->bit_rate = bitrate;
                s->codec_ctx->bit_rate_tolerance = bitrate / desc.fps * 6;
                LOG(LOG_LEVEL_INFO) << MOD_NAME << "Setting bitrate to " << bitrate << " bps.\n";
        } else {
                // set CRF unless explicitly specified CQP or ABR (bitrate)
                if (s->requested_crf >= 0.0 || (s->requested_bitrate == 0 && s->requested_bpp == 0.0 && s->requested_cqp == -1)) {
                        double crf = s->requested_crf >= 0.0 ? s->requested_crf : DEFAULT_X264_X265_CRF;
                        if (int rc = av_opt_set_double(s->codec_ctx->priv_data, "crf", crf, 0)) {
                                print_libav_error(LOG_LEVEL_WARNING, MOD_NAME "Warning: Unable to set CRF", rc);
                        } else {
                                log_msg(LOG_LEVEL_INFO, "[lavc] Setting CRF to %.2f.\n", crf);
                        }
                }
                if (s->requested_cqp >= 0) {
                        if (int rc = av_opt_set_int(s->codec_ctx->priv_data, "qp", s->requested_cqp, 0)) {
                                print_libav_error(LOG_LEVEL_WARNING, MOD_NAME "Warning: Unable to set CQP", rc);
                        } else {
                                log_msg(LOG_LEVEL_INFO, "[lavc] Setting CQP to %d.\n", s->requested_cqp);
                        }
                }
        }

        /* resolution must be a multiple of two */
        s->codec_ctx->width = desc.width;
        s->codec_ctx->height = desc.height;
        /* frames per second */
        s->codec_ctx->time_base = (AVRational){1,(int) desc.fps};
        if (s->requested_gop) {
                s->codec_ctx->gop_size = s->requested_gop;
        } else {
                s->codec_ctx->gop_size = DEFAULT_GOP_SIZE;
        }
        s->codec_ctx->max_b_frames = 0;

        s->codec_ctx->pix_fmt = pix_fmt;

        codec_params[ug_codec].set_param(s->codec_ctx, &s->params);
        set_thread_mode(s->codec_ctx, &s->params);

        if (!have_preset) {
                string preset{};
                if (codec_params[ug_codec].get_preset) {
                        preset = codec_params[ug_codec].get_preset(s->codec_ctx->codec->name, desc.width, desc.height, desc.fps);
                }

                if (!preset.empty() && preset != "defer"s) {
                        if (av_opt_set(s->codec_ctx->priv_data, "preset", preset.c_str(), 0) != 0) {
                                LOG(LOG_LEVEL_WARNING) << "[lavc] Warning: Unable to set preset.\n";
                        } else {
                                LOG(LOG_LEVEL_INFO) << "[lavc] Setting preset to " << preset <<  ".\n";
                        }
                }
                if (preset.empty()) {
                        LOG(LOG_LEVEL_WARNING) << "[lavc] Warning: Unable to find suitable preset for encoder " << s->codec_ctx->codec->name << ".\n";
                }
        }

        // set user supplied parameters
        for (auto item : s->lavc_opts) {
                if(av_opt_set(s->codec_ctx->priv_data, item.first.c_str(), item.second.c_str(), 0) != 0) {
                        log_msg(LOG_LEVEL_WARNING, "[lavc] Error: Unable to set '%s' to '%s'. Check command-line options.\n", item.first.c_str(), item.second.c_str());
                        return false;
                }
        }

        return true;
}

/**
 * Returns a UltraGrid decoder needed to decode from the UltraGrid codec in
 * to out with respect to conversions in @ref conversions. Therefore it should
 * be feasible to convert in to out and then convert out to av (last step may
 * be omitted if the format is native for both indicated in
 * ug_to_av_pixfmt_map).
 */
decoder_t get_decoder_from_uv_to_uv(codec_t in, AVPixelFormat av, codec_t *out) {
        bool slow[] = {false, true};
        for (auto use_slow : slow) {
                for (const auto *i = get_av_to_ug_pixfmts(); i->uv_codec != VIDEO_CODEC_NONE; ++i) { // no conversion needed - direct mapping
                        auto decoder = get_decoder_from_to(in, i->uv_codec, use_slow);
                        if (decoder && i->av_pixfmt == av) {
                                *out = i->uv_codec;
                                return decoder;
                        }
                }
                for (const auto *c = get_uv_to_av_conversions(); c->src != VIDEO_CODEC_NONE; c++) { // conversion needed
                        auto decoder = get_decoder_from_to(in, c->src, use_slow);
                        if (decoder && c->dst == av) {
                                *out = c->src;
                                return decoder;
                        }
                }
        }

        *out = VIDEO_CODEC_NONE;
        return nullptr;
}

static int get_subsampling(enum AVPixelFormat fmt) {
        const struct AVPixFmtDescriptor *pd = av_pix_fmt_desc_get(fmt);
        if (pd->log2_chroma_w == 0 && pd->log2_chroma_h == 0) {
                return 444;
        }
        if (pd->log2_chroma_w == 1 && pd->log2_chroma_h == 0) {
                return 422;
        }
        if (pd->log2_chroma_w == 1 && pd->log2_chroma_h == 1) {
                return 420;
        }
        return 0; // other (todo)
}

/**
 * Returns list of pix_fmts that UltraGrid can supply to the encoder.
 * The list is ordered according to input description and requested subsampling.
 */
static list<enum AVPixelFormat> get_available_pix_fmts(struct video_desc in_desc,
                AVCodec *codec, int requested_subsampling, codec_t force_conv_to)
{
        list<enum AVPixelFormat> fmts;

#ifdef HWACC_VAAPI
        if (regex_match(codec->name, regex(".*vaapi.*"))) {
                fmts.push_back(AV_PIX_FMT_VAAPI);
        }
#else
        UNUSED(codec);
#endif

        // add the format itself if it matches the ultragrid one
        if (get_ug_to_av_pixfmt(in_desc.color_spec) != AV_PIX_FMT_NONE) {
                if (!force_conv_to || force_conv_to == in_desc.color_spec) {
                        fmts.push_back(get_ug_to_av_pixfmt(in_desc.color_spec));
                }
        }

        vector<enum AVPixelFormat> available_formats; // those for that there exitst a conversion and respect requested subsampling (if given)
        for (const auto *i = get_av_to_ug_pixfmts(); i->uv_codec != VIDEO_CODEC_NONE; ++i) { // no conversion needed - direct mapping
                if (get_decoder_from_to(in_desc.color_spec, i->uv_codec, true)) {
                        int codec_subsampling = get_subsampling(i->av_pixfmt);
                        if ((requested_subsampling == 0 ||
                                        requested_subsampling == codec_subsampling) &&
                                       (!force_conv_to || force_conv_to == i->uv_codec)) {
                                available_formats.push_back(i->av_pixfmt);
                        }
                }
        }
        for (const auto *c = get_uv_to_av_conversions(); c->src != VIDEO_CODEC_NONE; c++) { // conversion needed
                if (c->src == in_desc.color_spec ||
                                get_decoder_from_to(in_desc.color_spec, c->src, true)) {
                        int codec_subsampling = get_subsampling(c->dst);
                        if ((requested_subsampling == 0 ||
                                        requested_subsampling == codec_subsampling) &&
                                       (!force_conv_to || force_conv_to == c->src)) {
                                available_formats.push_back(c->dst);
                        }
                }
        }

        int bits_per_comp = get_bits_per_component(in_desc.color_spec);
        bool is_rgb = codec_is_a_rgb(in_desc.color_spec);
        int preferred_subsampling = requested_subsampling;
        if (requested_subsampling == 0) {
                if (codec_is_420(in_desc.color_spec)) { /// @todo perhaps better would be take the subs. directly
                        preferred_subsampling = 420;
                } else {
                        preferred_subsampling = 422;
                }
        }
        // sort
        sort(available_formats.begin(), available_formats.end(), [bits_per_comp, is_rgb, preferred_subsampling](enum AVPixelFormat a, enum AVPixelFormat b) {
                const struct AVPixFmtDescriptor *pda = av_pix_fmt_desc_get(a);
                const struct AVPixFmtDescriptor *pdb = av_pix_fmt_desc_get(b);
#if defined(FF_API_PLUS1_MINUS1)
                int deptha = pda->comp[0].depth;
                int depthb = pdb->comp[0].depth;
#else
                int deptha = pda->comp[0].depth_minus1;
                int depthb = pdb->comp[0].depth_minus1;
#endif
#if defined(AV_PIX_FMT_FLAG_RGB)
                bool rgba = pda->flags & AV_PIX_FMT_FLAG_RGB;
                bool rgbb = pdb->flags & AV_PIX_FMT_FLAG_RGB;
#else
                bool rgba = pda->flags & PIX_FMT_RGB;
                bool rgbb = pdb->flags & PIX_FMT_RGB;
#endif
                int subsa = get_subsampling(a);
                int subsb = get_subsampling(b);

                if (rgba != rgbb) {
                        if (rgba == is_rgb) {
                                return true;
                        }
                        return false;
                }
                if (deptha != depthb) {
                        // either a or b is lower than bits_per_comp - sort higher bit depth first
                        if (deptha < bits_per_comp || depthb < bits_per_comp) {
                                return deptha > depthb;
                        }
                        // both are equal or higher - sort lower bit depth first
                        return deptha < depthb;
                }
                if (subsa != subsb) {
                        if (subsa == preferred_subsampling) {
                                return true;
                        }
                        if (subsb == preferred_subsampling) {
                                return false;
                        }
                        return subsa > subsb;
                }
                return a < b;
                        });

        for (auto &c : available_formats) {
                fmts.push_back(c);
        }

        return fmts;

}

ADD_TO_PARAM("lavc-use-codec",
                "* lavc-use-codec=<c>\n"
                "  Restrict codec to use user specified pixel fmt. Use either FFmpeg name\n"
                "  (eg. nv12, yuv422p10le or yuv444p10le) or UltraGrid pixel formats names\n"
                "  (v210, R10k, UYVY etc.). See wiki for more info.\n");
/**
 * Returns ordered list of codec preferences for input description and
 * requested_subsampling.
 */
list<enum AVPixelFormat> get_requested_pix_fmts(struct video_desc in_desc,
                AVCodec *codec, int requested_subsampling) {
        codec_t force_conv_to = VIDEO_CODEC_NONE; // if non-zero, use only this codec as a target
                                                  // of UG conversions (before FFMPEG conversion)
                                                  // or (likely) no conversion at all
        if (get_commandline_param("lavc-use-codec")) {
                const char *val = get_commandline_param("lavc-use-codec");
                enum AVPixelFormat fmt = av_get_pix_fmt(val);
                if (fmt != AV_PIX_FMT_NONE) {
                        return { fmt };
                }
                force_conv_to = get_codec_from_name(val);
                if (!force_conv_to) {
                        LOG(LOG_LEVEL_FATAL) << MOD_NAME << "Wrong codec string: " << val << ".\n";
                        exit_uv(1);
                        return {};
                }
        }

        return get_available_pix_fmts(in_desc, codec, requested_subsampling, force_conv_to);
}

static bool try_open_codec(struct state_video_compress_libav *s,
                           AVPixelFormat &pix_fmt,
                           struct video_desc desc,
                           codec_t ug_codec,
                           const AVCodec *codec)
{
        // avcodec_alloc_context3 allocates context and sets default value
        s->codec_ctx = avcodec_alloc_context3(codec);
        if (!s->codec_ctx) {
                log_msg(LOG_LEVEL_ERROR, "Could not allocate video codec context\n");
                return false;
        }

        if (!set_codec_ctx_params(s, pix_fmt, desc, ug_codec)) {
                avcodec_free_context(&s->codec_ctx);
                s->codec_ctx = NULL;
                return false;
        }

        log_msg(LOG_LEVEL_VERBOSE, "[lavc] Trying pixfmt: %s\n", av_get_pix_fmt_name(pix_fmt));
#ifdef HWACC_VAAPI
        if (pix_fmt == AV_PIX_FMT_VAAPI){
                int ret = vaapi_init(s->codec_ctx);
                if (ret != 0) {
                        avcodec_free_context(&s->codec_ctx);
                        s->codec_ctx = NULL;
                        return false;
                }
                s->hwenc = true;
                s->hwframe = av_frame_alloc();
                av_hwframe_get_buffer(s->codec_ctx->hw_frames_ctx, s->hwframe, 0);
                pix_fmt = AV_PIX_FMT_NV12;
        }
#endif

        if (const AVPixFmtDescriptor * desc = av_pix_fmt_desc_get(pix_fmt)) { // defaults
                s->codec_ctx->colorspace = (desc->flags & AV_PIX_FMT_FLAG_RGB) != 0U ? AVCOL_SPC_RGB : AVCOL_SPC_BT709;
                s->codec_ctx->color_range = (desc->flags & AV_PIX_FMT_FLAG_RGB) != 0U ? AVCOL_RANGE_JPEG : AVCOL_RANGE_MPEG;
        }
        get_av_pixfmt_details(ug_codec, pix_fmt, &s->codec_ctx->colorspace, &s->codec_ctx->color_range);

        /* open it */
        pthread_mutex_lock(s->lavcd_global_lock);
        if (avcodec_open2(s->codec_ctx, codec, NULL) < 0) {
                avcodec_free_context(&s->codec_ctx);
                s->codec_ctx = NULL;
                log_msg(LOG_LEVEL_ERROR, "[lavc] Could not open codec for pixel format %s\n", av_get_pix_fmt_name(pix_fmt));
                pthread_mutex_unlock(s->lavcd_global_lock);
                return false;
        }
        pthread_mutex_unlock(s->lavcd_global_lock);

        return true;
}

static bool find_decoder(struct video_desc desc,
                AVPixelFormat pixfmt,
                codec_t *decoded_codec,
                decoder_t *decoder)
{
        if (get_ug_to_av_pixfmt(desc.color_spec) != AV_PIX_FMT_NONE
                        && pixfmt == get_ug_to_av_pixfmt(desc.color_spec)) {
                *decoded_codec = desc.color_spec;
                *decoder = vc_memcpy;
        } else {
                *decoder = get_decoder_from_uv_to_uv(desc.color_spec, pixfmt, decoded_codec);
        }

        return *decoder != nullptr;
}

static bool same_linesizes(codec_t codec, AVFrame *in_frame)
{
        if (codec_is_planar(codec)) {
                assert(get_bits_per_component(codec) == 8);
                int sub[8];
                codec_get_planes_subsampling(codec, sub);
                for (int i = 0; i < 4; ++i) {
                        if (sub[2 * i] == 0) {
                                return true;
                        }
                        if (in_frame->linesize[i] != (in_frame->width + sub[2 * i] - 1) / sub[2 * i]) {
                                return false;
                        }
                }
                return true;
        } else {
                return vc_get_linesize(in_frame->width, codec) == in_frame->linesize[0];
        }
}

static bool configure_with(struct state_video_compress_libav *s, struct video_desc desc)
{
        int ret;
        codec_t ug_codec = VIDEO_CODEC_NONE;
        AVPixelFormat pix_fmt;
        AVCodec *codec = nullptr;
#ifdef HAVE_SWSCALE
        sws_freeContext(s->sws_ctx);
        s->sws_ctx = nullptr;
        av_frame_free(&s->sws_frame);
        s->out_pixfmt = AV_PIX_FMT_NONE;
#endif //HAVE_SWSCALE

        s->params.fps = desc.fps;
        s->params.interlaced = desc.interlacing == INTERLACED_MERGED;

        // Open encoder specified by user if given
        if (!s->backend.empty()) {
                codec = avcodec_find_encoder_by_name(s->backend.c_str());
                if (!codec) {
                        log_msg(LOG_LEVEL_ERROR, "[lavc] Warning: requested encoder \"%s\" not found!\n",
                                        s->backend.c_str());
                        return false;
                }
                if (s->requested_codec_id != VIDEO_CODEC_NONE && s->requested_codec_id != get_av_to_ug_codec(codec->id)) {
                        LOG(LOG_LEVEL_WARNING) << MOD_NAME << "Encoder \"" << s->backend << "\" doesn't encode requested codec!\n";
                        return false;

                }
                ug_codec = get_av_to_ug_codec(codec->id);
                if (ug_codec == VIDEO_CODEC_NONE) {
                        log_msg(LOG_LEVEL_WARNING, "[lavc] Requested encoder not supported in UG!\n");
                        return false;
                }
        }

        if (ug_codec == VIDEO_CODEC_NONE) {
                if (s->requested_codec_id == VIDEO_CODEC_NONE) {
                        ug_codec = DEFAULT_CODEC;
                } else {
                        ug_codec = s->requested_codec_id;
                }
        }
        if (codec_params.find(ug_codec) == codec_params.end()) {
                log_msg(LOG_LEVEL_ERROR, "[lavc] Requested output codec isn't "
                                "currently supported.\n");
                return false;
        }

        // Else, try to open prefered encoder for requested codec
        if (!codec && codec_params[ug_codec].get_prefered_encoder) {
                const char *prefered_encoder = codec_params[ug_codec].get_prefered_encoder(
                                codec_is_a_rgb(desc.color_spec));
                codec = avcodec_find_encoder_by_name(prefered_encoder);
                if (!codec) {
                        log_msg(LOG_LEVEL_WARNING, "[lavc] Warning: prefered encoder \"%s\" not found! Trying default encoder.\n",
                                        prefered_encoder);
                }
        }
        // Finally, try to open any encoder for requested codec
        if (!codec) {
                codec = avcodec_find_encoder(get_ug_to_av_codec(ug_codec));
        }

        if (!codec) {
                log_msg(LOG_LEVEL_ERROR, "Libavcodec doesn't contain encoder for specified codec.\n"
                                "Hint: Check if you have libavcodec-extra package installed.\n");
                return false;
        } else {
                log_msg(LOG_LEVEL_NOTICE, "[lavc] Using codec: %s, encoder: %s\n",
                                get_codec_name(ug_codec), codec->name);
        }

        // Try to open the codec context
        // It is done in a loop because some pixel formats that are reported
        // by codec can actually fail (typically YUV444 in hevc_nvenc for Maxwell
        // cards).
        list<enum AVPixelFormat> requested_pix_fmt_it = get_requested_pix_fmts(desc, codec, s->requested_subsampling);
        while ((pix_fmt = get_first_matching_pix_fmt(requested_pix_fmt_it, codec->pix_fmts)) != AV_PIX_FMT_NONE) {
                if(try_open_codec(s, pix_fmt, desc, ug_codec, codec)){
                        break;
                }
	}

        if (pix_fmt == AV_PIX_FMT_NONE || log_level >= LOG_LEVEL_VERBOSE) {
                print_pix_fmts(get_requested_pix_fmts(desc, codec, s->requested_subsampling), codec->pix_fmts);
        }

#ifdef HAVE_SWSCALE
        if (pix_fmt == AV_PIX_FMT_NONE) {
                LOG(LOG_LEVEL_WARNING) << MOD_NAME "No direct decoder format for: " << get_codec_name(desc.color_spec) << ". Trying to convert with swscale instead.\n";
                for (const auto *pix = codec->pix_fmts; *pix != AV_PIX_FMT_NONE; ++pix) {
                        const AVPixFmtDescriptor *fmt_desc = av_pix_fmt_desc_get(*pix);
                        if (fmt_desc != nullptr && (fmt_desc->flags & AV_PIX_FMT_FLAG_HWACCEL) == 0U) {
                                AVPixelFormat curr_pix_fmt = *pix;
                                if (try_open_codec(s, curr_pix_fmt, desc, ug_codec, codec)) {
                                        pix_fmt = curr_pix_fmt;
                                        break;
                                }
                        }
                }
        }
#endif

        if (pix_fmt == AV_PIX_FMT_NONE) {
                log_msg(LOG_LEVEL_WARNING, "[lavc] Unable to find suitable pixel format for: %s.\n", get_codec_name(desc.color_spec));
                if (s->requested_subsampling != 0) {
                        log_msg(LOG_LEVEL_ERROR, "[lavc] Requested subsampling not supported. "
                                        "Try different subsampling, eg. "
                                        "\"subsampling={420,422,444}\".\n");
                }
                return false;
        }

        log_msg(LOG_LEVEL_INFO, "[lavc] Selected pixfmt: %s\n", av_get_pix_fmt_name(pix_fmt));
        s->selected_pixfmt = pix_fmt;

        if(!find_decoder(desc, s->selected_pixfmt, &s->decoded_codec, &s->decoder)){
                log_msg(LOG_LEVEL_ERROR, "[lavc] Failed to find a way to convert %s to %s\n",
                               get_codec_name(desc.color_spec), av_get_pix_fmt_name(s->selected_pixfmt));
#ifndef HAVE_SWSCALE
                return false;
#else
                log_msg(LOG_LEVEL_NOTICE, "[lavc] Attempting to use swscale to convert.\n");
                //get all AVPixelFormats we can convert to and pick the first
                auto fmts = get_available_pix_fmts(desc, codec, s->requested_subsampling, VIDEO_CODEC_NONE);
                s->out_pixfmt = s->selected_pixfmt;
                s->selected_pixfmt = fmts.front();
                if(!find_decoder(desc, s->selected_pixfmt, &s->decoded_codec, &s->decoder)){
                        //Should not happen as get_available_pix_fmts should only
                        //return formats we can decode to
                        log_msg(LOG_LEVEL_ERROR, "[lavc] Unable to convert even using swscale. Giving up.\n");
                        return false;
                }

                s->sws_ctx = getSwsContext(desc.width,
                                            desc.height,
                                            s->selected_pixfmt,
                                            desc.width,
                                            desc.height,
                                            s->out_pixfmt,
                                            SWS_POINT);
                if(!s->sws_ctx){
                        log_msg(LOG_LEVEL_ERROR, "[lavc] Unable to init sws context.\n");
                        return false;
                }

                s->sws_frame = av_frame_alloc();
                if (!s->sws_frame) {
                        log_msg(LOG_LEVEL_ERROR, "Could not allocate sws frame\n");
                        return false;
                }
                s->sws_frame->width = s->codec_ctx->width;
                s->sws_frame->height = s->codec_ctx->height;
                s->sws_frame->format = s->out_pixfmt;
                ret = av_image_alloc(s->sws_frame->data, s->sws_frame->linesize,
                                s->sws_frame->width, s->sws_frame->height,
                                s->out_pixfmt, 32);
                if (ret < 0) {
                        log_msg(LOG_LEVEL_ERROR, "Could not allocate raw picture buffer for sws\n");
                        return false;
                }

                log_msg(LOG_LEVEL_NOTICE, "[lavc] Using swscale to convert %s to %s.\n",
                                av_get_pix_fmt_name(s->selected_pixfmt),
                                av_get_pix_fmt_name(s->out_pixfmt));
#endif //HAVE_SWSCALE
        }

        s->decoded = (unsigned char *) malloc(vc_get_linesize(desc.width, s->decoded_codec) * desc.height);

        s->in_frame = av_frame_alloc();
        if (!s->in_frame) {
                log_msg(LOG_LEVEL_ERROR, "Could not allocate video frame\n");
                return false;
        }

        AVPixelFormat fmt = (s->hwenc) ? AV_PIX_FMT_NV12 : s->selected_pixfmt;
#if LIBAVCODEC_VERSION_MAJOR >= 53
        s->in_frame->format = fmt;
        s->in_frame->width = s->codec_ctx->width;
        s->in_frame->height = s->codec_ctx->height;
#endif

        /* the image can be allocated by any means and av_image_alloc() is
         * just the most convenient way if av_malloc() is to be used */
        ret = av_image_alloc(s->in_frame->data, s->in_frame->linesize,
                        s->codec_ctx->width, s->codec_ctx->height,
                        fmt, 32);
        if (ret < 0) {
                log_msg(LOG_LEVEL_ERROR, "Could not allocate raw picture buffer\n");
                return false;
        }
        // conversion needed
        if (get_ug_to_av_pixfmt(desc.color_spec) == AV_PIX_FMT_NONE
                        || get_ug_to_av_pixfmt(desc.color_spec) != s->selected_pixfmt) {
                for(int i = 0; i < s->params.conv_thread_count; ++i) {
                        int chunk_size = s->codec_ctx->height / s->params.conv_thread_count;
                        chunk_size = chunk_size / 2 * 2;
                        s->in_frame_part[i]->data[0] = s->in_frame->data[0] + s->in_frame->linesize[0] * i *
                                chunk_size;

                        if (av_pix_fmt_desc_get(s->selected_pixfmt)->log2_chroma_h == 1) { // eg. 4:2:0
                                chunk_size /= 2;
                        }
                        s->in_frame_part[i]->data[1] = s->in_frame->data[1] + s->in_frame->linesize[1] * i *
                                chunk_size;
                        s->in_frame_part[i]->data[2] = s->in_frame->data[2] + s->in_frame->linesize[2] * i *
                                chunk_size;
                        s->in_frame_part[i]->linesize[0] = s->in_frame->linesize[0];
                        s->in_frame_part[i]->linesize[1] = s->in_frame->linesize[1];
                        s->in_frame_part[i]->linesize[2] = s->in_frame->linesize[2];
                }
        } else if (same_linesizes(s->decoded_codec, s->in_frame)) {
                av_freep(s->in_frame->data); // allocated buffers won't be needed and pointers
                                             // will be filled by input buffers. av_image_alloc()
                                             // was called to fill linesizes, however.
        }

        s->saved_desc = desc;
        s->compressed_desc = desc;
        s->compressed_desc.color_spec = ug_codec;
        s->compressed_desc.tile_count = 1;

        s->out_codec = s->compressed_desc.color_spec;

        return true;
}

static pixfmt_callback_t select_pixfmt_callback(AVPixelFormat fmt, codec_t src) {
        // no conversion needed
        if (get_ug_to_av_pixfmt(src) != AV_PIX_FMT_NONE
                        && get_ug_to_av_pixfmt(src) == fmt) {
                return nullptr;
        }

        for (auto c = get_uv_to_av_conversions(); c->src != VIDEO_CODEC_NONE; c++) { // FFMPEG conversion needed
                if (c->src == src && c->dst == fmt) {
                        return c->func;
                }
        }

        log_msg(LOG_LEVEL_FATAL, "[lavc] Cannot find conversion to any of encoder supported pixel format.\n");
        abort();
}

struct my_task_data {
        void (*callback)(AVFrame *out_frame, unsigned char *in_data, int width, int height);
        AVFrame *out_frame;
        unsigned char *in_data;
        int width;
        int height;
};

void *my_task(void *arg);

void *my_task(void *arg) {
        struct my_task_data *data = (struct my_task_data *) arg;
        data->callback(data->out_frame, data->in_data, data->width, data->height);
        return NULL;
}

static shared_ptr<video_frame> libavcodec_compress_tile(struct module *mod, shared_ptr<video_frame> tx)
{
        struct state_video_compress_libav *s = (struct state_video_compress_libav *) mod->priv_data;
        static int frame_seq = 0;
        int ret;
        unsigned char *decoded;
        shared_ptr<video_frame> out{};
        list<unique_ptr<state_video_compress_libav, void (*)(void *)>> cleanup_callbacks; // at function exit handlers

        libavcodec_check_messages(s);

        if(!video_desc_eq_excl_param(video_desc_from_frame(tx.get()),
                                s->saved_desc, PARAM_TILE_COUNT)) {
                cleanup(s);
                int ret = configure_with(s, video_desc_from_frame(tx.get()));
                if(!ret) {
                        return {};
                }
        }

        auto dispose = [](struct video_frame *frame) {
#if LIBAVCODEC_VERSION_MAJOR >= 54 && LIBAVCODEC_VERSION_INT < AV_VERSION_INT(57, 37, 100)
                AVPacket *pkt = (AVPacket *) frame->callbacks.dispose_udata;
                av_packet_unref(pkt);
                free(pkt);
#else
                free(frame->tiles[0].data);
#endif // LIBAVCODEC_VERSION_MAJOR >= 54
                vf_free(frame);
        };
        out = shared_ptr<video_frame>(vf_alloc_desc(s->compressed_desc), dispose);
        vf_copy_metadata(out.get(), tx.get());
#if LIBAVCODEC_VERSION_MAJOR >= 54 && LIBAVCODEC_VERSION_INT < AV_VERSION_INT(57, 37, 100)
        int got_output;
        AVPacket *pkt;
        pkt = (AVPacket *) malloc(sizeof(AVPacket));
        av_init_packet(pkt);
        pkt->data = NULL;
        pkt->size = 0;
        out->callbacks.dispose_udata = pkt;
#else
        out->tiles[0].data = (char *) malloc(s->compressed_desc.width *
                        s->compressed_desc.height * 4);
#endif // LIBAVCODEC_VERSION_MAJOR >= 54

        s->in_frame->pts = frame_seq++;

        if (s->decoder != vc_memcpy) {
                unsigned char *line1 = (unsigned char *) tx->tiles[0].data;
                unsigned char *line2 = (unsigned char *) s->decoded;
                int src_linesize = vc_get_linesize(tx->tiles[0].width, tx->color_spec);
                int dst_linesize = vc_get_linesize(tx->tiles[0].width, s->decoded_codec);
                for (int i = 0; i < (int) tx->tiles[0].height; ++i) {
                        s->decoder(line2, line1, dst_linesize,
                                        0, 8, 16);
                        line1 += src_linesize;
                        line2 += dst_linesize;
                }
                decoded = s->decoded;
        } else {
                decoded = (unsigned char *) tx->tiles[0].data;
        }

        auto pixfmt_conv_callback = select_pixfmt_callback(s->selected_pixfmt, s->decoded_codec);
        if (pixfmt_conv_callback != nullptr) {
                vector<task_result_handle_t> handle(s->params.conv_thread_count);
                vector<struct my_task_data> data(s->params.conv_thread_count);
                for(int i = 0; i < s->params.conv_thread_count; ++i) {
                        data[i].callback = pixfmt_conv_callback;
                        data[i].out_frame = s->in_frame_part[i];

                        size_t height = tx->tiles[0].height / s->params.conv_thread_count;
                        // height needs to be even
                        height = height / 2 * 2;
                        if (i < s->params.conv_thread_count - 1) {
                                data[i].height = height;
                        } else { // we are last so we need to do the rest
                                data[i].height = tx->tiles[0].height -
                                        height * (s->params.conv_thread_count - 1);
                        }
                        data[i].width = tx->tiles[0].width;
                        data[i].in_data = decoded + i * height *
                                vc_get_linesize(tx->tiles[0].width, s->decoded_codec);

                        // run !
                        handle[i] = task_run_async(my_task, (void *) &data[i]);
                }

                for(int i = 0; i < s->params.conv_thread_count; ++i) {
                        wait_task(handle[i]);
                }
        } else { // no pixel format conversion needed
                if (codec_is_planar(s->decoded_codec) && !same_linesizes(s->decoded_codec, s->in_frame)) {
                        assert(get_bits_per_component(s->decoded_codec) == 8);
                        int sub[8];
                        codec_get_planes_subsampling(s->decoded_codec, sub);
                        unsigned char *in = decoded;
                        for (int i = 0; i < 4; ++i) {
                                if (sub[2 * i] == 0) {
                                        break;
                                }
                                int linesize = (s->in_frame->width + sub[2 * i] - 1) / sub[2 * i];
                                int lines = (s->in_frame->height + sub[2 * i + 1] - 1) / sub[2 * i + 1];
                                for (int y = 0; y < lines; ++y) {
                                        memcpy(s->in_frame->data[i] + y * s->in_frame->linesize[i], in, linesize);
                                        in += linesize;
                                }
                        }
                } else {
                        if (codec_is_planar(s->decoded_codec)) {
                                buf_get_planes(tx->tiles[0].width, tx->tiles[0].height, s->decoded_codec, (char *) decoded, (char **) s->in_frame->data);
                        } else {
                                s->in_frame->data[0] = (uint8_t *) decoded;
                        }
                        // prevent leaving dangling pointer to the input buffer that may
                        // be freed by cleanup()
                        std::unique_ptr<state_video_compress_libav, void (*)(void*)> clean_data_ptr{s,
                                static_cast<void(*)(void *)>([](void *state) {
                                                auto s = (state_video_compress_libav *) state;
                                                s->in_frame->data[0] = s->in_frame->data[1] = s->in_frame->data[2] = s->in_frame->data[3] = nullptr;
                                                })};
                        cleanup_callbacks.push_back(move(clean_data_ptr));
                }
        }

        AVFrame *frame = s->in_frame;
#ifdef HWACC_VAAPI
        if(s->hwenc){
                av_hwframe_transfer_data(s->hwframe, s->in_frame, 0);
                frame = s->hwframe;
        }
#endif

#ifdef HAVE_SWSCALE
        if(s->sws_ctx){
                sws_scale(s->sws_ctx,
                          s->in_frame->data,
                          s->in_frame->linesize,
                          0,
                          s->in_frame->height,
                          s->sws_frame->data,
                          s->sws_frame->linesize);
                frame = s->sws_frame;
        }
#endif //HAVE_SWSCALE

        /* encode the image */
#if LIBAVCODEC_VERSION_INT >= AV_VERSION_INT(57, 37, 100)
        out->tiles[0].data_len = 0;
        if (libav_codec_has_extradata(s->out_codec)) { // we need to store extradata for HuffYUV/FFV1 in the beginning
                out->tiles[0].data_len += sizeof(uint32_t) + s->codec_ctx->extradata_size;
                *(uint32_t *)(void *) out->tiles[0].data = s->codec_ctx->extradata_size;
                memcpy(out->tiles[0].data + sizeof(uint32_t), s->codec_ctx->extradata, s->codec_ctx->extradata_size);
        }

        ret = avcodec_send_frame(s->codec_ctx, frame);
        if (ret == 0) {
                AVPacket pkt;
                av_init_packet(&pkt);
                ret = avcodec_receive_packet(s->codec_ctx, &pkt);
                while (ret == 0) {
                        assert(pkt.size + out->tiles[0].data_len <= s->compressed_desc.width * s->compressed_desc.height * 4 - out->tiles[0].data_len);
                        memcpy((uint8_t *) out->tiles[0].data + out->tiles[0].data_len,
                                        pkt.data, pkt.size);
                        out->tiles[0].data_len += pkt.size;
                        av_packet_unref(&pkt);
                        ret = avcodec_receive_packet(s->codec_ctx, &pkt);
                }
                if (ret != AVERROR(EAGAIN) && ret != 0) {
                        print_libav_error(LOG_LEVEL_WARNING, "[lavc] Receive packet error", ret);
                }
        } else {
		print_libav_error(LOG_LEVEL_WARNING, "[lavc] Error encoding frame", ret);
                return {};
        }
#elif LIBAVCODEC_VERSION_MAJOR >= 54
        ret = avcodec_encode_video2(s->codec_ctx, pkt,
                        frame, &got_output);
        if (ret < 0) {
                log_msg(LOG_LEVEL_INFO, "Error encoding frame\n");
                return {};
        }

        if (got_output) {
                //printf("Write frame %3d (size=%5d)\n", frame_seq, s->pkt[buffer_idx].size);
                out->tiles[0].data = (char *) pkt->data;
                out->tiles[0].data_len = pkt->size;
        } else {
                return {};
        }
#else
        ret = avcodec_encode_video(s->codec_ctx, (uint8_t *) out->tiles[0].data,
                        out->tiles[0].width * out->tiles[0].height * 4,
                        frame);
        if (ret < 0) {
                log_msg(LOG_LEVEL_INFO, "Error encoding frame\n");
                return {};
        }

        if (ret) {
                //printf("Write frame %3d (size=%5d)\n", frame_seq, s->pkt[buffer_idx].size);
                out->tiles[0].data_len = ret;
        } else {
                return {};
        }
#endif // LIBAVCODEC_VERSION_MAJOR >= 54

        if (out->tiles[0].data_len == 0) { // videotoolbox returns sometimes frames with pkt->size == 0 but got_output == true
                return {};
        }

        return out;
}

static void cleanup(struct state_video_compress_libav *s)
{
        if(s->codec_ctx) {
#if LIBAVCODEC_VERSION_INT >= AV_VERSION_INT(57, 37, 100)
		int ret;
		ret = avcodec_send_frame(s->codec_ctx, NULL);
		if (ret != 0) {
			log_msg(LOG_LEVEL_WARNING, "[lavc] Unexpected return value %d\n",
					ret);
		}
		do {
			AVPacket pkt;
			av_init_packet(&pkt);
			ret = avcodec_receive_packet(s->codec_ctx, &pkt);
			av_packet_unref(&pkt);
			if (ret != 0 && ret != AVERROR_EOF) {
				log_msg(LOG_LEVEL_WARNING, "[lavc] Unexpected return value %d\n",
						ret);
				break;
			}
		} while (ret != AVERROR_EOF);
#endif
                pthread_mutex_lock(s->lavcd_global_lock);
                avcodec_close(s->codec_ctx);
                avcodec_free_context(&s->codec_ctx);
                pthread_mutex_unlock(s->lavcd_global_lock);
                s->codec_ctx = NULL;
        }
        if(s->in_frame) {
                av_freep(s->in_frame->data);
                av_free(s->in_frame);
                s->in_frame = NULL;
        }
        free(s->decoded);
        s->decoded = NULL;

        av_frame_free(&s->hwframe);

#ifdef HAVE_SWSCALE
        sws_freeContext(s->sws_ctx);
        av_frame_free(&s->sws_frame);
#endif //HAVE_SWSCALE
}

static void libavcodec_compress_done(struct module *mod)
{
        struct state_video_compress_libav *s = (struct state_video_compress_libav *) mod->priv_data;

        cleanup(s);

        rm_release_shared_lock(LAVCD_LOCK_NAME);
        for(int i = 0; i < s->params.conv_thread_count; i++) {
                av_free(s->in_frame_part[i]);
        }
        free(s->in_frame_part);
        delete s;
}

static void set_thread_mode(AVCodecContext *codec_ctx, struct setparam_param *param)
{
        int threads = 0;

        try {
                threads = stoi(param->thread_mode);
        } catch(invalid_argument &) { // not a number
        }

        if (param->thread_mode == "no") { // disable threading (which may have been enabled previously
                codec_ctx->thread_type = 0;
                codec_ctx->thread_count = 1;
        } else if (param->thread_mode == "slice" || threads > 0) {
                // zero should mean count equal to the number of virtual cores
                if (codec_ctx->codec->capabilities & AV_CODEC_CAP_SLICE_THREADS) {
                        codec_ctx->thread_count = threads; // if "slice", 0 means auto
                        codec_ctx->thread_type = FF_THREAD_SLICE;
                } else {
                        log_msg(LOG_LEVEL_WARNING, "[lavc] Warning: Codec doesn't support slice-based multithreading.\n");
                }
        } else if (param->thread_mode == "frame") {
                if (codec_ctx->codec->capabilities & AV_CODEC_CAP_FRAME_THREADS) {
                        codec_ctx->thread_count = 0;
                        codec_ctx->thread_type = FF_THREAD_FRAME;
                } else {
                        log_msg(LOG_LEVEL_WARNING, "[lavc] Warning: Codec doesn't support frame-based multithreading.\n");
                }
        } else {
                log_msg(LOG_LEVEL_ERROR, "[lavc] Warning: unknown thread mode: %s.\n", param->thread_mode.c_str());
        }
}

static void setparam_default(AVCodecContext *codec_ctx, struct setparam_param * /* param */)
{
        if (codec_ctx->codec->id == AV_CODEC_ID_JPEG2000) {
                log_msg(LOG_LEVEL_WARNING, "[lavc] J2K support is experimental and may be broken!\n");
        }
}

static void setparam_jpeg(AVCodecContext *codec_ctx, struct setparam_param *param)
{
        if (param->thread_mode == "slice") {
                // zero should mean count equal to the number of virtual cores
                codec_ctx->thread_count = 0;
                codec_ctx->thread_type = FF_THREAD_SLICE;
        }

        if (av_opt_set(codec_ctx->priv_data, "huffman", "default", 0) != 0) {
                log_msg(LOG_LEVEL_WARNING, "[lavc] Warning: Cannot set default Huffman tables.\n");
        }
}

static void configure_amf([[maybe_unused]] AVCodecContext *codec_ctx, [[maybe_unused]] struct setparam_param *param) {
        if (int ret = av_opt_set(codec_ctx->priv_data, "header_insertion_mode", "gop", 0)) {
                print_libav_error(LOG_LEVEL_WARNING, MOD_NAME "Unable to header_insertion_mode for AMF", ret);
        }
}

ADD_TO_PARAM("lavc-h264-interlaced-dct", "* lavc-h264-interlaced-dct\n"
                 "  Use interlaced DCT for H.264\n");
static void configure_x264_x265(AVCodecContext *codec_ctx, struct setparam_param *param)
{
        const char *tune;
        if (codec_ctx->codec->id == AV_CODEC_ID_H264) {
                tune = "zerolatency,fastdecode";
        } else { // x265 supports only single tune parameter
                tune = "zerolatency";
        }
        int ret = av_opt_set(codec_ctx->priv_data, "tune", tune, 0);
        if (ret != 0) {
                log_msg(LOG_LEVEL_WARNING, "[lavc] Unable to set tune %s.\n", tune);
        }

        // try to keep frame sizes as even as possible
        codec_ctx->rc_max_rate = codec_ctx->bit_rate;
        //codec_ctx->rc_min_rate = s->codec_ctx->bit_rate / 4 * 3;
        //codec_ctx->rc_buffer_aggressivity = 1.0;
        codec_ctx->rc_buffer_size = codec_ctx->rc_max_rate / param->fps * 8; // "emulate" CBR. Note that less than 8 frame sizes causes encoder buffer overflows and artifacts in stream.
        codec_ctx->qcompress = codec_ctx->codec->id == AV_CODEC_ID_H265 ? 0.5F : 0.0F;
        //codec_ctx->qblur = 0.0f;
        //codec_ctx->rc_min_vbv_overflow_use = 1.0f;
        //codec_ctx->rc_max_available_vbv_use = 1.0f;
        codec_ctx->qmin = 0;
        codec_ctx->qmax = 69;
        codec_ctx->max_qdiff = 69;
        //codec_ctx->rc_qsquish = 0;
        //codec_ctx->scenechange_threshold = 100;

        if (get_commandline_param("lavc-h264-interlaced-dct")) {
                // this options increases variance in frame sizes quite a lot
                if (param->interlaced) {
                        codec_ctx->flags |= AV_CODEC_FLAG_INTERLACED_DCT;
                }
        }

        string x265_params = "keyint=" + to_string(codec_ctx->gop_size);
        /// turn on periodic intra refresh, unless explicitely disabled
        if (!param->no_periodic_intra){
                int ret = AVERROR_ENCODER_NOT_FOUND;
                codec_ctx->refs = 1;
                if ("libx264"s == codec_ctx->codec->name || "libx264rgb"s == codec_ctx->codec->name) {
                        ret = av_opt_set(codec_ctx->priv_data, "intra-refresh", "1", 0);
                } else if ("libx265"s == codec_ctx->codec->name) {
                        x265_params += ":intra-refresh=1";
                        ret = av_opt_set(codec_ctx->priv_data, "x265-params", x265_params.c_str(), 0);
                }
                if (ret != 0) {
                        print_libav_error(LOG_LEVEL_WARNING, "[lavc] Unable to set Intra Refresh", ret);
                }
        } else if ("libx265"s == codec_ctx->codec->name) {
                int ret = av_opt_set(codec_ctx->priv_data, "x265-params", x265_params.c_str(), 0);
                if (ret != 0) {
                        print_libav_error(LOG_LEVEL_WARNING, "[lavc] Unable to set x265-params", ret);
                }
        }
}

static void configure_qsv(AVCodecContext *codec_ctx, struct setparam_param *param)
{
        int ret;
        ret = av_opt_set(codec_ctx->priv_data, "look_ahead", "0", 0);
        if (ret != 0) {
                log_msg(LOG_LEVEL_WARNING, "[lavc] Unable to set unset look-ahead.\n");
        }
        if (!param->no_periodic_intra) {
                ret = av_opt_set(codec_ctx->priv_data, "int_ref_type", "vertical", 0);
                if (ret != 0) {
                        log_msg(LOG_LEVEL_WARNING, "[lavc] Unable to set intra refresh.\n");
                }
#if 0
                ret = av_opt_set(codec_ctx->priv_data, "int_ref_cycle_size", "100", 0);
                if (ret != 0) {
                        log_msg(LOG_LEVEL_WARNING, "[lavc] Unable to set intra refresh size.\n");
                }
#endif
        }
        codec_ctx->rc_max_rate = codec_ctx->bit_rate;
        // no look-ahead and rc_max_rate == bit_rate result in use of CBR for QSV
}

static void configure_nvenc(AVCodecContext *codec_ctx, struct setparam_param *param)
{
        const char *preset = DEFAULT_NVENC_PRESET;

        // important: if "tune" is not supported, then FALLBACK_NVENC_PRESET must be used (it is correlated). If unsupported preset
        // were given, setting would succeed but would cause runtime errors.
        if (int rc = av_opt_set(codec_ctx->priv_data, "tune", DEFAULT_NVENC_TUNE, 0)) {
                array<char, LIBAV_ERRBUF_LEN> errbuf{};
                av_strerror(rc, errbuf.data(), errbuf.size());
                LOG(LOG_LEVEL_WARNING) << "[lavc] Cannot set NVENC tune to \"" << DEFAULT_NVENC_TUNE << "\" (" << errbuf.data() << "). Possibly old libavcodec or compiled with old NVIDIA NVENC headers.\n";
                preset = FALLBACK_NVENC_PRESET;
        }
        if (int rc = av_opt_set(codec_ctx->priv_data, "preset", preset, 0)) {
                array<char, LIBAV_ERRBUF_LEN> errbuf{};
                av_strerror(rc, errbuf.data(), errbuf.size());
                LOG(LOG_LEVEL_WARNING) << "[lavc] Cannot set NVENC preset to: " << preset << " (" << errbuf.data() << ").\n";
        } else {
                LOG(LOG_LEVEL_INFO) << "[lavc] Setting NVENC preset to " << preset << ".\n";
        }

        int ret = av_opt_set(codec_ctx->priv_data, "rc", DEFAULT_NVENC_RC, 0);
        if (ret != 0) { // older FFMPEG had only cbr
                LOG(LOG_LEVEL_WARNING) << "[lavc] Cannot set RC " << DEFAULT_NVENC_RC << ".\n";
        }

        ret = av_opt_set(codec_ctx->priv_data, "spatial_aq", "0", 0);
        if (ret != 0) {
                log_msg(LOG_LEVEL_WARNING, "[lavc] Unable to unset spatial AQ.\n");
        }
        char gpu[3] = "";
        snprintf(gpu, 2, "%d", cuda_devices[0]);
        ret = av_opt_set(codec_ctx->priv_data, "gpu", gpu, 0);
        if (ret != 0) {
                log_msg(LOG_LEVEL_WARNING, "[lavc] Unable to set GPU.\n");
        }
        ret = av_opt_set(codec_ctx->priv_data, "delay", "0", 0);
        if (ret != 0) {
                log_msg(LOG_LEVEL_WARNING, "[lavc] Unable to set delay.\n");
        }
        ret = av_opt_set(codec_ctx->priv_data, "zerolatency", "1", 0);
        if (ret != 0) {
                log_msg(LOG_LEVEL_WARNING, "[lavc] Unable to set zero latency operation (no reordering delay).\n");
        }
        codec_ctx->rc_max_rate = codec_ctx->bit_rate;
        codec_ctx->rc_buffer_size = codec_ctx->rc_max_rate / param->fps;
}

static void configure_svt(AVCodecContext *codec_ctx, struct setparam_param * /* param */)
{
        char force_idr_val[2] = "";
        int ret;

        // see FFMPEG modules' sources for semantics
        force_idr_val[0] = strcmp(codec_ctx->codec->name, "libsvt_hevc") == 0 ? '0' : '1';
        ret = av_opt_set(codec_ctx->priv_data, "forced-idr", force_idr_val, 0);
        if (ret != 0) {
                log_msg(LOG_LEVEL_WARNING, "[lavc] Unable to set IDR for SVT.\n");
        }

        if ("libsvt_hevc"s == codec_ctx->codec->name) {
                if (int ret = av_opt_set_int(codec_ctx->priv_data, "tile_row_cnt", 4, 0)) {
                        print_libav_error(LOG_LEVEL_WARNING, MOD_NAME "[lavc] Unable Tile Row Count for SVT", ret);
                }
                if (int ret = av_opt_set_int(codec_ctx->priv_data, "tile_col_cnt", 4, 0)) {
                        print_libav_error(LOG_LEVEL_WARNING, MOD_NAME "[lavc] Unable Tile Column Count for SVT", ret);
                }
                if (int ret = av_opt_set_int(codec_ctx->priv_data, "tile_slice_mode", 1, 0)) {
                        print_libav_error(LOG_LEVEL_WARNING, MOD_NAME "[lavc] Unable Tile Slice Mode for SVT", ret);
                }
        } else { // libsvtav1
                // tile_columns and tile_rows are Log2 values
                if (int ret = av_opt_set_int(codec_ctx->priv_data, "tile_columns", 2, 0)) {
                        print_libav_error(LOG_LEVEL_WARNING, MOD_NAME "[lavc] Unable Tile Row Count for SVT", ret);
                }
                if (int ret = av_opt_set_int(codec_ctx->priv_data, "tile_rows", 2, 0)) {
                        print_libav_error(LOG_LEVEL_WARNING, MOD_NAME "[lavc] Unable Tile Column Count for SVT", ret);
                }
        }
}

static void setparam_h264_h265_av1(AVCodecContext *codec_ctx, struct setparam_param *param)
{
        if (regex_match(codec_ctx->codec->name, regex(".*_amf"))) {
                configure_amf(codec_ctx, param);
        } else if (strncmp(codec_ctx->codec->name, "libx264", strlen("libx264")) == 0 || // libx264 and libx264rgb
                        strcmp(codec_ctx->codec->name, "libx265") == 0) {
                configure_x264_x265(codec_ctx, param);
        } else if (regex_match(codec_ctx->codec->name, regex(".*nvenc.*"))) {
                configure_nvenc(codec_ctx, param);
        } else if (strcmp(codec_ctx->codec->name, "h264_qsv") == 0 ||
                        strcmp(codec_ctx->codec->name, "hevc_qsv") == 0) {
                configure_qsv(codec_ctx, param);
        } else if (strstr(codec_ctx->codec->name, "libsvt_") == codec_ctx->codec->name) {
                configure_svt(codec_ctx, param);
        } else {
                log_msg(LOG_LEVEL_WARNING, "[lavc] Warning: Unknown encoder %s. Using default configuration values.\n", codec_ctx->codec->name);
        }
}

void show_encoder_help(string const &name) {
        cout << "Options for " << style::bold << name << style::reset << ":\n";
        auto *codec = avcodec_find_encoder_by_name(name.c_str());
        if (codec == nullptr) {
                LOG(LOG_LEVEL_ERROR) << MOD_NAME << "Unable to find encoder " << name << "!\n";
                return;
        }
        const auto *opt = codec->priv_class->option;
        if (opt == nullptr) {
                return;
        }
        while (opt->name != nullptr) {
                cout << (opt->offset == 0 ? "\t\t* " : "\t- ");
                cout << style::bold << opt->name << style::reset << (opt->help != nullptr && strlen(opt->help) > 0 ? " - "s + opt->help : ""s) << "\n";
                opt++;
        }
}

/// @retval "defer" - preset will be set individually later (NVENC)
static string get_h264_h265_preset(string const & enc_name, int width, int height, double fps)
{
        if (enc_name == "libx264" || enc_name == "libx264rgb") {
                if (width <= 1920 && height <= 1080 && fps <= 30) {
                        return string("veryfast");
                } else {
                        return string("ultrafast");
                }
        } else if (enc_name == "libx265") {
                return string("ultrafast");
        } else if (regex_match(enc_name, regex(".*nvenc.*"))) { // so far, there are at least nvenc, nvenc_h264 and h264_nvenc variants
                return "defer"s; // nvenc preset is handled with configure_nvenc()
        } else if (enc_name == "h264_qsv") {
                return string(DEFAULT_QSV_PRESET);
        } else {
                return {};
        }
}

static void setparam_vp8_vp9(AVCodecContext *codec_ctx, struct setparam_param *param)
{
        codec_ctx->thread_count = param->conv_thread_count;
        codec_ctx->rc_buffer_size = codec_ctx->bit_rate / param->fps;
        //codec_ctx->rc_buffer_aggressivity = 0.5;
        if (av_opt_set(codec_ctx->priv_data, "deadline", "realtime", 0) != 0) {
                log_msg(LOG_LEVEL_WARNING, "[lavc] Unable to set deadline.\n");
        }

        if (av_opt_set(codec_ctx->priv_data, "cpu-used", "8", 0)) {
                log_msg(LOG_LEVEL_WARNING, "[lavc] Unable to set quality/speed ratio modifier.\n");
        }
}

static void libavcodec_check_messages(struct state_video_compress_libav *s)
{
        struct message *msg;
        while ((msg = check_message(&s->module_data))) {
                struct msg_change_compress_data *data =
                        (struct msg_change_compress_data *) msg;
                struct response *r;
                if (parse_fmt(s, data->config_string) == 0) {
                        log_msg(LOG_LEVEL_NOTICE, "[Libavcodec] Compression successfully changed.\n");
                        r = new_response(RESPONSE_OK, NULL);
                } else {
                        log_msg(LOG_LEVEL_ERROR, "[Libavcodec] Unable to change compression!\n");
                        r = new_response(RESPONSE_INT_SERV_ERR, NULL);
                }
                memset(&s->saved_desc, 0, sizeof(s->saved_desc));
                free_message(msg, r);
        }

}

const struct video_compress_info libavcodec_info = {
        "libavcodec",
        libavcodec_compress_init,
        NULL,
        libavcodec_compress_tile,
        NULL,
        NULL,
        NULL,
        NULL,
        get_libavcodec_presets,
        get_libavcodec_module_info,
};

REGISTER_MODULE(libavcodec, &libavcodec_info, LIBRARY_CLASS_VIDEO_COMPRESS, VIDEO_COMPRESS_ABI_VERSION);

} // end of anonymous namespace