// ffmpeg_lesson01.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
extern "C"
{
#include "libavcodec/avcodec.h"
#include "libavcodec/version.h"
#include "libavformat/avformat.h"
#include "libavfilter/avfiltergraph.h"
#include "libavfilter/buffersink.h"
#include "libavfilter/buffersrc.h"
#include "libavutil/avutil.h"
#include "libavutil/opt.h"
#include "libavutil/pixdesc.h"
#include "libswscale/swscale.h"
};


int SaveYuv(unsigned char *buf, int wrap, int xsize, int ysize, char *filename)
{
    FILE *f;
    int i;

    f = fopen(filename, "ab+");
    for (i = 0; i<ysize; i++)
    {
        fwrite(buf + i * wrap, 1, xsize, f);
    }
    fclose(f);
    return 1;
}

int main()
{


    printf("\n\n");
    printf("正在检查是否是标准C++：");
#if (!defined(__STDC__))
    printf("非标准C！\n");
#elif defined(__STDC_VERSION__)
    printf("标准C版本：%ld。", __STDC_VERSION__);
#else
    printf("旧的标准C。\n");
#endif


    printf("\nHello FFmpeg!\n");
    printf("avcodec_version: %d\n", avcodec_version());
    printf("\n");


#define VIDEO_PATH "D://xiongmao.flv"
char *outputfilename = "d:\\test3.yuv";

    av_register_all();
    //注册所有文件格式和编码器的库。


    //下面函数将文件头信息读取到传入的参数中。
    AVFormatContext *pFormatContext = NULL;
    if (avformat_open_input(&pFormatContext,VIDEO_PATH,NULL,NULL) != 0) {
        printf("打开输入文件失败!\n");
        return -1;
    }
    else {
        printf("文件打开成功！\n");
    }
    //下面开始检测文件的流信息
    if (avformat_find_stream_info(pFormatContext,NULL) < 0) {
        printf("未发现文件流信息\n");
        return -1;
    }
    else {
        printf("发现文件流信息！\n");
    }

    //打印文件信息
    //av_dump_format(pFormatContext,0,VIDEO_PATH,0);

    //查找视频流
    int videoStream = -1;
    for (int i = 0; i < pFormatContext->nb_streams; i++)
    {

        if (pFormatContext->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
            videoStream = i;
            printf("发现视频流，索引ID: %d\n",videoStream);
            break;
        }
    }


    //查找音频流
    int audioStream = -1;

    for (int i = 0; i < pFormatContext->nb_streams; i++)
    {

        if (pFormatContext->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO) {
            audioStream = i;
            printf("发现音频流，索引ID: %d\n", audioStream);
            break;
        }
    }


    //查找到音视频流之后，开始查找音视频对应的解码器。有关编解码器的信息被称为“编码器上下文”
    AVCodecContext *pCodecContext;
    AVCodec *pCodec;

    //查找视频流的编解码信息
    pCodecContext = pFormatContext->streams[videoStream]->codec;

    pCodec = avcodec_find_decoder(pCodecContext->codec_id);
    if (pCodec == NULL) {
        printf("未找到视频流解码器！\n");
        return -1;
    }else {
        printf("找到视频流解码器,ID:%d\n", pCodecContext->codec_id);
    }

    //打开视频编码器
    if (avcodec_open2(pCodecContext,pCodec,NULL) < 0) {

        printf("打开解码器失败！");
        return -1;
    }   else {
        printf("视频解码器打开成功！\n");
    }


   //下面要从视频流中读取一个视频帧并保存成24位RGB色的PPM文件。
    AVFrame *pFrame;
    //下面开始读取数据
    int frameFinished;
    AVPacket packet;


    //旧的版本使用img_convert就可以。后面改成sws_scale.
    //功能更强大。需要详细指出源信息和目的帧信息。
    SwsContext *pSwsCtx;
    pSwsCtx = sws_getContext(pCodecContext->width,pCodecContext->height,pCodecContext->pix_fmt,pCodecContext->width,pCodecContext->height, AV_PIX_FMT_RGB24, SWS_BICUBIC,NULL,NULL,NULL);



    int i = 0;
    while (av_read_frame(pFormatContext,&packet) >= 0) {

        if (packet.stream_index == videoStream) {//是否是视频流的数据包

            pFrame = av_frame_alloc();

            avcodec_decode_video2(pCodecContext, pFrame, &frameFinished, &packet);

            if (frameFinished) {
                SaveYuv(pFrame->data[0], pFrame->linesize[0], pCodecContext->width, pCodecContext->height, outputfilename);
                SaveYuv(pFrame->data[1], pFrame->linesize[1], pCodecContext->width / 2, pCodecContext->height / 2, outputfilename);
                SaveYuv(pFrame->data[2], pFrame->linesize[2], pCodecContext->width / 2, pCodecContext->height / 2, outputfilename);
            }
            av_free(pFrame);
        }

        //释放packet
        av_free_packet(&packet);
    }

    //关闭解码器
    avcodec_close(pCodecContext);

    //关闭打开的文件
    avformat_close_input(&pFormatContext);


    return 0;
}