opencv ffmepg 播放视频

// 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>  #ifdef __cplusplus  }#endif  static void CopyDate(AVFrame *pFrame, int width, int height, int time);static void SaveFrame(AVFrame *pFrame, int width, int height, int iFrame);int main(int argc, const char * argv[]){    AVFormatContext *pFormatCtx = NULL;    int             i, videoStream;    AVCodecContext  *pCodecCtx;    AVCodec         *pCodec;    AVFrame         *pFrame;    AVFrame         *pFrameRGB;    AVPacket        packet;    int             frameFinished;    int             numBytes;    uint8_t         *buffer;    // Register all formats and codecs      av_register_all();    char* filename = "up.mp4";    // Open video file      if (avformat_open_input(&pFormatCtx, filename, NULL, NULL) != 0)        // if(avformat_open_input(NULL, argv[1], NULL, NULL)!=0)          return -1; // Couldn't open file                     // Retrieve stream information      if (avformat_find_stream_info(pFormatCtx, NULL) < 0)        return -1; // Couldn't find stream information                     // Dump information about file onto standard error      av_dump_format(pFormatCtx, 0, filename, false);    // Find the first video stream      videoStream = -1;    for (i = 0; i < pFormatCtx->nb_streams; i++)        if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)        {            videoStream = i;            break;        }    if (videoStream == -1)        return -1; // Didn't find a video stream                     // Get a pointer to the codec context for the video stream      pCodecCtx = pFormatCtx->streams[videoStream]->codec;    // Find the decoder for the video stream      pCodec = avcodec_find_decoder(pCodecCtx->codec_id);    if (pCodec == NULL)        return -1; // Codec not found                     // Open codec      if (avcodec_open2(pCodecCtx, pCodec, 0) < 0)        return -1; // Could not open codec                     // Hack to correct wrong frame rates that seem to be generated by some codecs      if (pCodecCtx->time_base.num > 1000 && pCodecCtx->time_base.den == 1)        pCodecCtx->time_base.den = 1000;    // Allocate video frame      pFrame = av_frame_alloc();    // Allocate an AVFrame structure      pFrameRGB = av_frame_alloc();    if (pFrameRGB == NULL)        return -1;    // Determine required buffer size and allocate buffer      numBytes = avpicture_get_size(AV_PIX_FMT_RGB24, pCodecCtx->width,        pCodecCtx->height);    //buffer=malloc(numBytes);      buffer = (uint8_t *)av_malloc(numBytes * sizeof(uint8_t));    // Assign appropriate parts of buffer to image planes in pFrameRGB      avpicture_fill((AVPicture *)pFrameRGB, buffer, AV_PIX_FMT_RGB24,        pCodecCtx->width, pCodecCtx->height);    // Read frames and save first five frames to disk      i = 0;    long prepts = 0;    while (av_read_frame(pFormatCtx, &packet) >= 0)    {        // Is this a packet from the video stream?          if (packet.stream_index == videoStream)        {            // Decode video frame              avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);            // Did we get a video frame?              if (frameFinished)            {                static struct SwsContext *img_convert_ctx;#if 0                  // Older removed code                  // Convert the image from its native format to RGB swscale                  img_convert((AVPicture *)pFrameRGB, PIX_FMT_RGB24,                    (AVPicture*)pFrame, pCodecCtx->pix_fmt, pCodecCtx->width,                    pCodecCtx->height);                // function template, for reference                  int sws_scale(struct SwsContext *context, uint8_t* src[], int srcStride[], int srcSliceY,                    int srcSliceH, uint8_t* dst[], int dstStride[]);#endif                  // Convert the image into YUV format that SDL uses                  if (img_convert_ctx == NULL) {                    int w = pCodecCtx->width;                    int h = pCodecCtx->height;                    img_convert_ctx = sws_getContext(w, h,                        pCodecCtx->pix_fmt,                        w, h, AV_PIX_FMT_RGB24, SWS_BICUBIC,                        NULL, NULL, NULL);                    if (img_convert_ctx == NULL) {                        fprintf(stderr, "Cannot initialize the conversion context!\n");                        exit(1);                    }                }                int ret = sws_scale(img_convert_ctx, pFrame->data, pFrame->linesize, 0,                    pCodecCtx->height, pFrameRGB->data, pFrameRGB->linesize);#if 0                   // this use to be true, as of 1/2009, but apparently it is no longer true in 3/2009                  if (ret) {                    fprintf(stderr, "SWS_Scale failed [%d]!\n", ret);                    exit(-1);                }#endif                  // Save the frame to disk                  if (i++ <= 5)                    SaveFrame(pFrameRGB, pCodecCtx->width, pCodecCtx->height, i);                CopyDate(pFrameRGB, pCodecCtx->width, pCodecCtx->height, packet.pts - prepts);                prepts = packet.pts;            }        }        // Free the packet that was allocated by av_read_frame          av_free_packet(&packet);    }    // Free the RGB image      //free(buffer);      av_free(buffer);    av_free(pFrameRGB);    // Free the YUV frame      av_free(pFrame);    // Close the codec      avcodec_close(pCodecCtx);    // Close the video file      avformat_close_input(&pFormatCtx);    system("Pause");    return 0;}static void CopyDate(AVFrame *pFrame, int width, int height, int time){    if (time <= 0) time = 1;    int     nChannels;    int     stepWidth;    uchar*  pData;    cv::Mat frameImage(cv::Size(width, height), CV_8UC3, cv::Scalar(0));    stepWidth = frameImage.step;    nChannels = frameImage.channels();    pData = frameImage.data;    for (int i = 0; i < height; i++)    {        for (int j = 0; j < width; j++)        {            pData[i*stepWidth + j*nChannels + 0] = pFrame->data[0][i*pFrame->linesize[0] + j*nChannels + 2];            pData[i*stepWidth + j*nChannels + 1] = pFrame->data[0][i*pFrame->linesize[0] + j*nChannels + 1];            pData[i*stepWidth + j*nChannels + 2] = pFrame->data[0][i*pFrame->linesize[0] + j*nChannels + 0];        }    }    cv::namedWindow("Video", cv::WINDOW_NORMAL);    cv::imshow("Video", frameImage);    cv::waitKey(time);}static void SaveFrame(AVFrame *pFrame, int width, int height, int iFrame){    FILE *pFile;    char szFilename[32];    int  y;    // Open file      sprintf(szFilename, "frame%d.ppm", iFrame);    pFile = fopen(szFilename, "wb");    if (pFile == NULL)        return;    // Write header      fprintf(pFile, "P6\n%d %d\n255\n", width, height);    // Write pixel data      for (y = 0; y < height; y++)        fwrite(pFrame->data[0] + y*pFrame->linesize[0], 1, width * 3, pFile);    // Close file      fclose(pFile);}