#include <iostream>
#include <string.h>
#include <sstream>

#define __STDC_CONSTANT_MACROS

extern "C" {
#include <libavutil/pixdesc.h>
#include <libavutil/imgutils.h>
#include <libavutil/samplefmt.h>
#include <libavutil/timestamp.h>
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
}

void demuxing_decoding(const char* filename)
{
    puts("注册...");

    AVFormatContext* formatContext = nullptr;
    if (0 != avformat_open_input(&formatContext, filename, NULL, NULL))
    {
        puts("avformat_open_input失败.");
        return;
    }
    puts("avformat_open_input...");

    if (avformat_find_stream_info(formatContext, NULL) < 0)
    {
        puts("avformat_find_stream_info失败.");
        return;
    }
    puts("avformat_find_stream_info...");


    //获取视频流的索引位置
    //遍历所有类型的流（音频流、视频流、字幕流），找到视频流
    int video_stream_idx = -1;

    //number of streams
    for (int i = 0; i < formatContext->nb_streams; i++)
    {
        //流的类型
        if (formatContext->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO)
        {
            video_stream_idx = i;
            break;
        }
    }

    if (video_stream_idx == -1)
    {
        printf("%s", "找不到视频流\n");
        return;
    }

    AVStream* video_st = formatContext->streams[video_stream_idx];
    AVCodec *videCodec = avcodec_find_decoder(video_st->codecpar->codec_id);
    AVCodecContext* videoContext = avcodec_alloc_context3(videCodec);
    avcodec_parameters_to_context(videoContext, video_st->codecpar);
    avcodec_open2(videoContext, videCodec, nullptr);

    uint8_t *video_dst_data[4] = { NULL };
    int video_dst_linesize[4];
    int video_dst_bufsize = av_image_alloc(video_dst_data, video_dst_linesize, videoContext->width, videoContext->height, videoContext->pix_fmt, 1);

    //音频
    int audio_stream_idx = av_find_best_stream(formatContext, AVMEDIA_TYPE_AUDIO, -1, -1, NULL, 0);
    AVStream* audio_st = formatContext->streams[audio_stream_idx];
    AVCodec* audioCodec = avcodec_find_decoder(audio_st->codecpar->codec_id);
    AVCodecContext* audioContext = avcodec_alloc_context3(audioCodec);
    avcodec_parameters_to_context(audioContext, audio_st->codecpar);
    avcodec_open2(audioContext, audioCodec, nullptr);

    av_dump_format(formatContext, 0, filename, 0);

    AVFrame* frame = av_frame_alloc();

    AVPacket pkt;
    av_init_packet(&pkt);
    pkt.data = NULL;
    pkt.size = 0;
    std::cout << videCodec->name << "\n";
    std::cout << audioCodec->name << "\n";

    FILE *videofile = NULL;
    char video_name[128] = { 0 };
    sprintf_s(video_name, 128, "output\\demuxing_video.%s", videCodec->name);
    fopen_s(&videofile, video_name, "wb");

    FILE *audiofile = NULL;

    char audio_name[128] = { 0 };
    sprintf_s(audio_name, 128, "output\\demuxing_audio.%s", audioCodec->name);
    fopen_s(&audiofile, audio_name, "wb");

    while (av_read_frame(formatContext, &pkt) >= 0) 
    {
        if (pkt.stream_index == video_stream_idx)
        {
            avcodec_send_packet(videoContext, &pkt);
            while (0 == avcodec_receive_frame(videoContext, frame))
            {
                av_image_copy(video_dst_data, video_dst_linesize, (const uint8_t **)frame->data, frame->linesize, videoContext->pix_fmt, videoContext->width, videoContext->height);
                fwrite(video_dst_data[0], 1, video_dst_bufsize, videofile);
                puts("写入视频");
            }
        }
        else if (pkt.stream_index == audio_stream_idx)
        {
            avcodec_send_packet(audioContext, &pkt);
            while (0 == avcodec_receive_frame(audioContext, frame))
            {
                size_t unpadded_linesize = frame->nb_samples * av_get_bytes_per_sample((AVSampleFormat)frame->format);
                fwrite(frame->extended_data[0], 1, unpadded_linesize, audiofile);
                puts("写入音频");
            }
        }

        av_packet_unref(&pkt);
    }

    fclose(videofile);
    fclose(audiofile);
    avcodec_free_context(&videoContext);
    avcodec_free_context(&audioContext);
    avformat_close_input(&formatContext);
    av_frame_free(&frame);
    av_free(video_dst_data[0]);
}




int main()
{
    demuxing_decoding("./frag_bunny.mp4");
}