// FFMpeg + OpenCV demo  
#include <stdio.h>  
#include <opencv2/core/core.hpp>  
#include <opencv2/highgui/highgui.hpp>  

#ifdef __cplusplus  
extern "C" {
#endif  

#include <libavformat/avformat.h>  
#include <libavcodec/avcodec.h>  
#include <libswscale/swscale.h>  
#include <libavformat/avformat.h>  
#include <libavcodec/avcodec.h>  
#include <libswscale/swscale.h>  
#include <libavutil/opt.h>
#include <libavcodec/avcodec.h>
#include <libavutil/channel_layout.h>
#include <libavutil/common.h>
#include <libavutil/imgutils.h>
#include <libavutil/mathematics.h>
#include <libavutil/samplefmt.h>

#ifdef __cplusplus  
}
#endif  

#include <iostream>

static void CopyDate(AVFrame *pFrame, int width, int height, int time);
static void SaveFrame(AVFrame *pFrame, int width, int height, int iFrame);

using namespace cv;
using namespace std;

int main(int argc, char* argv[])
{
	int result = 0;
	av_register_all(); // 註冊所有FFmpeg庫所支援的檔案格式和codec

	AVFormatContext* pFormatCtx;
	char* filename = "up.mp4"; //輸入檔名

	// step1: 開啟媒體檔案,最後2個引數是用來指定檔案格式，buffer大小和格式引數，設定成NULL的話，libavformat庫會自動去探測它們
	result = avformat_open_input(&pFormatCtx, filename, NULL, NULL);
	if (result != 0)
	{
		cout << "open file fail" << endl;
		return -1;
	}
	cout << "open file succ" << endl;

	// step2: 查詢資訊流的資訊
	result = avformat_find_stream_info(pFormatCtx, NULL);
	if (result != 0)
	{
		cout << "find stream fail" << endl;
		return -1;
	}
	cout << "find stream succ" << endl;

	// step3: 列印資訊
	//av_dump_format(pFormatCtx, 0, filename, 0);

	// step4：找到video流資料
	int i = 0;
	int videoStream = -1;
	AVCodecContext* pCodecCtx = NULL;
	for (i = 0; i < pFormatCtx->nb_streams; i++)
	{
		if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)
		{
			videoStream = i;
			break;
		}
	}

	if (videoStream == -1)
	{
		cout << "find stream video fail" << endl;
		return -1;
	}
	cout << "find stream video succ." << endl;

	// 得到video編碼格式
	pCodecCtx = pFormatCtx->streams[videoStream]->codec;
	
	// step5: 得到解碼器
	AVCodec* pCodec = NULL;
	pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
	if (pCodec == NULL)
	{
		cout << "find decoder fail" << endl;
		return -1;
	}
	cout << "find decoder succ" << endl;

	result = avcodec_open2(pCodecCtx, pCodec, NULL);
	if (result != 0)
	{
		cout << "open codec fail" << endl;
		return -1;
	}
	cout << "open codec succ" << endl;

	// step6: 申請原始資料幀 和 RGB幀記憶體
	AVFrame* pFrame = NULL;
	AVFrame* pFrameRGB = NULL;
	pFrame = av_frame_alloc();
	pFrameRGB = av_frame_alloc();
	if (pFrame == NULL || pFrameRGB == NULL)
	{
		return -1;
	}

	int numBytes = avpicture_get_size(AV_PIX_FMT_RGB24, pCodecCtx->width, pCodecCtx->height);
	uint8_t* buffer = (uint8_t*)av_malloc(numBytes * sizeof(uint8_t));
	avpicture_fill((AVPicture*)pFrameRGB, buffer, AV_PIX_FMT_RGB24, pCodecCtx->width, pCodecCtx->height);

	int frameFinishsed = 0;
	AVPacket packet;
	i = 0; 

	// step7: 建立格式轉化文字
	SwsContext * pSwxCtx = sws_getContext(
		pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt,
		pCodecCtx->width, pCodecCtx->height, AV_PIX_FMT_RGB24,
		SWS_BILINEAR, 0, 0, 0);

	cv::Mat image(pCodecCtx->height, pCodecCtx->width, CV_8UC3);
	int b = 0;
	int g = 1;
	int r = 2;

	while (true)
	{
		// 得到資料包
		result = av_read_frame(pFormatCtx, &packet);
		if (result != 0)
		{
			break;
		}

		if (packet.stream_index == videoStream)
		{
			// 解碼
			avcodec_decode_video2(pCodecCtx, pFrame, &frameFinishsed, &packet);

			if (frameFinishsed)
			{
				// 轉換
				sws_scale(pSwxCtx, pFrame->data, pFrame->linesize, 0, pCodecCtx->height,
					pFrameRGB->data, pFrameRGB->linesize);

				for (int m = 0; m < pCodecCtx->height; m++)
				{
					for (int n = 0; n < pCodecCtx->width; n++)
					{
						image.at<Vec3b>(m, n)[r] = pFrameRGB->data[0][3 * (m*pCodecCtx->width + n) + 0];
						image.at<Vec3b>(m, n)[g] = pFrameRGB->data[0][3 * (m*pCodecCtx->width + n) + 1];
						image.at<Vec3b>(m, n)[b] = pFrameRGB->data[0][3 * (m*pCodecCtx->width + n) + 2];
					}
				}
				cv::imshow("pic", image);
				cv::waitKey(30);
			}
		}

		av_free_packet(&packet);
	}
	
	avformat_close_input(&pFormatCtx);

	system("pause");
	return 0;
}