rtsp codec

CMakeLists.txt

cmake_minimum_required(VERSION 3.14)

PROJECT(m)

SET(CMAKE_CXX_STANDARD 11)

FIND_PATH(AVCODEC_INCLUDE_DIR libavcodec/avcodec.h)
FIND_LIBRARY(AVCODEC_LIBRARY avcodec)

FIND_PATH(AVFORMAT_INCLUDE_DIR libavformat/avformat.h)
FIND_LIBRARY(AVFORMAT_LIBRARY avformat)

AUX_SOURCE_DIRECTORY(src DIR_SRCS)
AUX_SOURCE_DIRECTORY(src/video DIR_SRCS)

SET(M_SRCS
        ${DIR_SRCS})

ADD_EXECUTABLE(${PROJECT_NAME} ${M_SRCS})

TARGET_INCLUDE_DIRECTORIES(${PROJECT_NAME} PRIVATE ${AVCODEC_INCLUDE_DIR} ${AVFORMAT_INCLUDE_DIR})
TARGET_LINK_LIBRARIES(${PROJECT_NAME} ${AVCODEC_LIBRARY} ${AVFORMAT_LIBRARY})

codec.cc

//
// Created by Yanlong He on 2019/11/29.
//

#include "codec.h"

namespace m {
    namespace detect {
        Codec::Codec(std::string url)
                : _url(std::move(url)) {
            setOptions();
        }

        void Codec::open() {
            AVFormatContext *fmtCtx = avformat_alloc_context();

            avformat_open_input(&fmtCtx, _url.c_str(), nullptr, &_opt);
            _fmtCtx.reset(fmtCtx);

            avformat_find_stream_info(fmtCtx, nullptr);

            int ret, streamIndex;
            AVCodec *codec = nullptr;
            AVStream *st;

            ret = av_find_best_stream(fmtCtx, AVMEDIA_TYPE_VIDEO, -1, -1, &codec, 0);

            if (ret < 0) {
                return;
            }

            streamIndex = ret;
            st = fmtCtx->streams[streamIndex];

            codec = avcodec_find_decoder(st->codecpar->codec_id);

            _codecContext = avcodec_alloc_context3(codec);

            avcodec_parameters_to_context(_codecContext, st->codecpar);

            AVDictionary *opt = nullptr;
            av_dict_set(&opt, "threads", "1", 0);
            avcodec_open2(_codecContext, codec, &opt);
            av_dict_free(&opt);

            av_init_packet(&_packet);
            _frame.reset(av_frame_alloc());
            av_seek_frame(fmtCtx, streamIndex, 0, AVSEEK_FLAG_BACKWARD);
            avformat_flush(fmtCtx);
        }

        AVFrame *Codec::frame() {
            AVFrame *f = nullptr;
            if (av_read_frame(_fmtCtx.get(), &_packet) == 0) {
                if (_packet.stream_index == _streamIndex) {
                    int response = avcodec_send_packet(_codecContext, &_packet);
                    if (response >= 0) {
                        response = avcodec_receive_frame(_codecContext, _frame.get());
                        std::cout << response << std::endl;
                        if (response == AVERROR(EAGAIN) || response == AVERROR_EOF) {
                            std::cout << "receive err: " << response << std::endl;
                        } else if (response < 0) {

                        } else if (response >= 0) {
                            f = _frame.get();
                        }
                    } else {
                        std::cout << "send packet err: " << response << std::endl;
                    }
                }
            } else {
                std::cout << "read frame err" << std::endl;
            }

            return f;
        }

        void Codec::setOptions() {
            av_dict_set(&_opt, "allowed_media_types", "video", 0);
            av_dict_set(&_opt, "reconnect_streamed", "1", 0);
            av_dict_set(&_opt, "nobuffer", "1", 0);
            av_dict_set(&_opt, "analyzeduration", "0", 0);
            av_dict_set(&_opt, "rtsp_transport", "tcp", 0);
            av_dict_set(&_opt, "buffer_size", "2097152", 0);
            av_dict_set(&_opt, "max_delay", "0", 0);
            av_dict_set(&_opt, "stimeout", "30000000", 0);
        }
    }
}

codec.h

//
// Created by Yanlong He on 2019/11/29.
//

#ifndef M_CODEC_H
#define M_CODEC_H

#include <iostream>
#include <utility>

extern "C" {
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libavutil/dict.h>
};

namespace m {
    namespace detect {
        class Codec {

        private:
            std::string _url;
            AVDictionary *_opt = nullptr;
            std::unique_ptr<AVFormatContext> _fmtCtx;
            std::unique_ptr<AVFrame> _frame;
            AVPacket _packet;
            AVCodecContext *_codecContext = nullptr;
            int _streamIndex;

            void setOptions();

        public:
            explicit Codec(std::string url);

            void open();

            AVFrame* frame();
        };
    }
}


#endif //M_CODEC_H

main.cc

//
// Created by Yanlong He on 2019/11/29.
//

#include <iostream>
#include "video/codec.h"

int main(int argc, char **argv) {

    m::detect::Codec codec("rtsp://127.0.0.1/live");
    codec.open();

    while (1) {
        AVFrame *frame = codec.frame();
        if (frame != nullptr) {
            std::cout << frame->width << " x " << frame->height << std::endl;
        }
    }
    return 0;
}

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