Recherche avancée

Sur d’autres sites (4881)

• How to seek in FFmpeg C/C++

  2 août 2017, par DRiFTy

  Does anyone know how to implement seeking by seconds (or milliseconds) in FFmpeg. I currently have a loop running through the frames of a video using av_read_frame() and I want to determine what time this frame should be at in seconds. If it gets to a certain point then I want to seek to a later point in the video. By the way it is not a video player, just processing the frames. Ive heard I should be able to get the dts or pts from the packet but its always returning 0.

• How to check if FFmpeg process is complete

  5 juillet 2017, par lllazo

  How can I check if ffmpeg process is complete.
  Like if I want to perform overlaying of image to video, I want to determine when the process is completed or if the output file is already complete.

  So from this command

    ffmpeg -i original.mp4 -i watermark.png -filter_complex "overlay=(W-w)/2:(H-h)/2" output.mp4

  How can I determine if output.mp4 is already complete.
  Because if I have another function to transfer the output file somewhere, the transferred file is still incomplete by the time transfer is executed.

• Libav AVFrame to Opencv Mat to AVPacket conversion

  14 mars 2018, par Davood Falahati

  I am new to libav and I am writing a video manipulation software which uses opencv as its heart. What I did is briefly as below :

  1- read the video packet

  2- decode the packet into AVFrame

  3- convert
  the AVFrame to CV Mat

  4- manipulate the Mat

  5- convert the CV Mat
  into AVFrame

  6- encode the AVFrame into AVPacket

  7- write the packet

  8- goto 1

  I read dranger tutorial in http://dranger.com/ffmpeg/tutorial01.html and I also used decoding_encoding example. I can read the video, extract video frames and convert them to CV Mat. My problem starts from converting from cv Mat to AVFrame and encode it to AVPacket.

  Would you please help me with this ?

  Here is my code :

  int main(int argc, char **argv)
  
  {
  
  AVOutputFormat *ofmt = NULL;
  
  AVFormatContext *ifmt_ctx = NULL, *ofmt_ctx = NULL;
  
  AVPacket pkt;
  
  AVCodecContext    *pCodecCtx = NULL;
  
  AVCodec           *pCodec = NULL;
  
  AVFrame           *pFrame = NULL;
  
  AVFrame           *pFrameRGB = NULL;
  
  int videoStream=-1;
  
  int audioStream=-1;
  
  int               frameFinished;
  
  int               numBytes;
  
  uint8_t           *buffer = NULL;
  
  struct SwsContext *sws_ctx = NULL;
  
  FrameManipulation *mal_frame;
  
  
  
  const char *in_filename, *out_filename;
  
  int ret, i;
  
  if (argc < 3) {
  
  
  
      printf("usage: %s input output\n"
  
             "API example program to remux a media file with libavformat and libavcodec.\n"
  
             "The output format is guessed according to the file extension.\n"
  
             "\n", argv[0]);
  
      return 1;
  
  }
  
  in_filename  = arg[1];
  
  out_filename = arg[2];
  
  av_register_all();
  
  if ((ret = avformat_open_input(&ifmt_ctx, in_filename, 0, 0)) < 0) {
  
      fprintf(stderr, "Could not open input file '%s'", in_filename);
  
      goto end;
  
  }
  
  
  
  if ((ret = avformat_find_stream_info(ifmt_ctx, 0)) < 0) {
  
      fprintf(stderr, "Failed to retrieve input stream information");
  
      goto end;
  
  }
  
  
  
  av_dump_format(ifmt_ctx, 0, in_filename, 0);
  
  avformat_alloc_output_context2(&ofmt_ctx, NULL, NULL, out_filename);
  
  
  
  if (!ofmt_ctx) {
  
      fprintf(stderr, "Could not create output context\n");
  
      ret = AVERROR_UNKNOWN;
  
      goto end;
  
  }
  
  
  
  ofmt = ofmt_ctx->oformat;
  
  
  
  for (i = 0; i < ifmt_ctx->nb_streams; i++) {
  
      AVStream *in_stream = ifmt_ctx->streams[i];
  
      AVStream *out_stream = avformat_new_stream(ofmt_ctx, in_stream->codec->codec);
  
  
  
      if(ifmt_ctx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO &&
  
         videoStream < 0) {
  
             videoStream=i;
  
      }
  
  
  
      if(ifmt_ctx->streams[i]->codec->codec_type==AVMEDIA_TYPE_AUDIO &&
  
         audioStream < 0) {
  
              audioStream=i;
  
      }
  
  
  
      if (!out_stream) {
  
          fprintf(stderr, "Failed allocating output stream\n");
  
          ret = AVERROR_UNKNOWN;
  
          goto end;
  
      }
  
  
  
      ret = avcodec_copy_context(out_stream->codec, in_stream->codec);
  
  
  
      if (ret < 0) {
  
          fprintf(stderr, "Failed to copy context from input to output stream codec context\n");
  
          goto end;
  
      }
  
  
  
      out_stream->codec->codec_tag = 0;
  
  
  
      if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER)
  
         out_stream->codec->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
  
  }
  
  
  
  pCodec=avcodec_find_decoder(ifmt_ctx->streams[videoStream]->codec->codec_id);
  
  pCodecCtx = avcodec_alloc_context3(pCodec);
  
  
  
  if(avcodec_copy_context(pCodecCtx, ifmt_ctx->streams[videoStream]->codec) != 0) {
  
    fprintf(stderr, "Couldn't copy codec context");
  
    return -1; // Error copying codec context
  
  }
  
  
  
  // Open codec
  
   if(avcodec_open2(pCodecCtx, pCodec, NULL)<0)
  
     return -1; // Could not open codec
  
  
  
  // Allocate video frame
  
   pFrame=av_frame_alloc();
  
  
  
   // Allocate an AVFrame structure
  
   pFrameRGB=av_frame_alloc();
  
  
  
   // Determine required buffer size and allocate buffer
  
   numBytes=avpicture_get_size(AV_PIX_FMT_RGB24, ifmt_ctx->streams[videoStream]->codec->width,
  
                   ifmt_ctx->streams[videoStream]->codec->height);
  
  
  
   buffer=(uint8_t *)av_malloc(numBytes*sizeof(uint8_t));
  
  
  
   // Assign appropriate parts of buffer to image planes in pFrameRGB
  
   // Note that pFrameRGB is an AVFrame, but AVFrame is a superset
  
   // of AVPicture
  
   avpicture_fill((AVPicture *)pFrameRGB, buffer, AV_PIX_FMT_BGR24,
  
          ifmt_ctx->streams[videoStream]->codec->width, ifmt_ctx->streams[videoStream]->codec->height);
  
  
  
   av_dump_format(ofmt_ctx, 0, out_filename, 1);
  
  
  
   if (!(ofmt->flags & AVFMT_NOFILE)) {
  
      ret = avio_open(&ofmt_ctx->pb, out_filename, AVIO_FLAG_WRITE);
  
      if (ret < 0) {
  
          fprintf(stderr, "Could not open output file '%s'", out_filename);
  
          goto end;
  
      }
  
  }
  
  
  
  ret = avformat_write_header(ofmt_ctx, NULL);
  
  if (ret < 0) {
  
      fprintf(stderr, "Error occurred when opening output file\n");
  
      goto end;
  
  }
  
  
  
  // Assign appropriate parts of buffer to image planes in pFrameRGB
  
  // Note that pFrameRGB is an AVFrame, but AVFrame is a superset
  
  // of AVPicture
  
  
  
  avpicture_fill((AVPicture *)pFrameRGB, buffer, AV_PIX_FMT_BGR24,
  
                     ifmt_ctx->streams[videoStream]->codec->width,
  
                     ifmt_ctx->streams[videoStream]->codec->height);
  
  
  
  // initialize SWS context for software scaling
  
  sws_ctx = sws_getContext(
  
               ifmt_ctx->streams[videoStream]->codec->width,
  
               ifmt_ctx->streams[videoStream]->codec->height,
  
               ifmt_ctx->streams[videoStream]->codec->pix_fmt,
  
               ifmt_ctx->streams[videoStream]->codec->width,
  
               ifmt_ctx->streams[videoStream]->codec->height,
  
               AV_PIX_FMT_BGR24,
  
               SWS_BICUBIC,
  
               NULL,
  
               NULL,
  
               NULL
  
               );
  
  // Loop through packets
  
  while (1) {
  
  
  
      AVStream *in_stream, *out_stream;
  
      ret = av_read_frame(ifmt_ctx, &pkt);
  
      if(pkt.stream_index==videoStream)
  
  
  
       // Decode video frame
  
        avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &pkt);
  
  
  
        if(frameFinished) {
  
                  sws_scale(sws_ctx, (uint8_t const * const *)pFrame->data,
  
                  pFrame->linesize, 0, pCodecCtx->height,
  
                  pFrameRGB->data, pFrameRGB->linesize);
  
                  cv::Mat img= mal_frame->process(
  
                            pFrameRGB,pFrame->width,pFrame->height);
  
  /* My problem is Here ------------*/
  
  
  
  
  
      avpicture_fill((AVPicture*)pFrameRGB, 
  
                       img.data, 
  
                       PIX_FMT_BGR24, 
  
                       outStream->codec->width, 
  
                       outStream->codec->height);
  
  
  
      pFrameRGB->width =  ifmt_ctx->streams[videoStream]->codec->width;
  
      pFrameRGB->height = ifmt_ctx->streams[videoStream]->codec->height;
  
  
  
              avcodec_encode_video2(ifmt_ctx->streams[videoStream]->codec , 
  
                                                       &pkt , pFrameRGB , &gotPacket);
  
  /*
  
  I get this error
  
  [swscaler @ 0x14b58a0] bad src image pointers
  
  [swscaler @ 0x14b58a0] bad src image pointers
  
  */
  
  
  
  /* My Problem Ends here ---------- */
  
  
  
      }
  
  
  
      if (ret < 0)
  
  
  
          break;
  
  
  
      in_stream  = ifmt_ctx->streams[pkt.stream_index];
  
  
  
      out_stream = ofmt_ctx->streams[pkt.stream_index];
  
  
  
  
  
  
  
      //log_packet(ifmt_ctx, &pkt, "in");
  
  
  
      /* copy packet */
  
  
  
      pkt.pts = av_rescale_q_rnd(pkt.pts, in_stream->time_base, out_stream->time_base,
  
  
  
                                 AV_ROUND_NEAR_INF);
  
  
  
  
  
  
  
      pkt.dts = av_rescale_q_rnd(pkt.dts, in_stream->time_base, out_stream->time_base, AV_ROUND_NEAR_INF);
  
  
  
      pkt.duration = av_rescale_q(pkt.duration, in_stream->time_base, out_stream->time_base);
  
  
  
      pkt.pos = -1;
  
  
  
      log_packet(ofmt_ctx, &pkt, "out");
  
  
  
      ret = av_interleaved_write_frame(ofmt_ctx, &pkt);
  
  
  
      if (ret < 0) {
  
  
  
          fprintf(stderr, "Error muxing packet\n");
  
  
  
          break;
  
  
  
      }
  
  
  
      av_free_packet(&pkt);
  
  
  
  }
  
  
  
  av_write_trailer(ofmt_ctx);
  
  
  
  end:
  
  
  
  avformat_close_input(&ifmt_ctx);
  
  
  
  /* close output */
  
  
  
  if (ofmt_ctx && !(ofmt->flags & AVFMT_NOFILE))
  
  
  
      avio_closep(&ofmt_ctx->pb);
  
  
  
  avformat_free_context(ofmt_ctx);
  
  
  
  if (ret < 0 && ret != AVERROR_EOF) {
  
  
  
      return 1;
  
  
  
  }
  
  
  
  return 0;
  
  
  
  }

  When I run this code, I get unknown fatal error in this part :

     /* My problem is Here ------------*/
  
  
  
  
  
      avpicture_fill((AVPicture*)pFrameRGB, 
  
                       img.data, 
  
                       PIX_FMT_BGR24, 
  
                       outStream->codec->width, 
  
                       outStream->codec->height);
  
  
  
      pFrameRGB->width =  ifmt_ctx->streams[videoStream]->codec->width;
  
      pFrameRGB->height = ifmt_ctx->streams[videoStream]->codec->height;
  
  
  
              avcodec_encode_video2(ifmt_ctx->streams[videoStream]->codec , 
  
                                                       &pkt , pFrameRGB , &gotPacket);
  
  /*
  
  I get this error
  
  [swscaler @ 0x14b58a0] bad src image pointers
  
  [swscaler @ 0x14b58a0] bad src image pointers
  
  */
  
  
  
  /* My Problem Ends here ---------- */

  Here is where I want to convert back cv Mat to AVFrame and encode it to AVPacket. I appreciate your help.