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• FFMPEG : Decode video in h264rgb/libx264rgb error

  9 février 2018, par Furan

  I did a small program to encode raw images in h264rgb codec with ffmpeg.
  I use this codec because I needed to encode lossless rgb images (not possible with the classic h264 codec).

  But now, I have a problem. I’m not able to decode the video generated with ffmpeg. I did a second small program for that, but I get a segfault when I reach the avcodec_decode_video2() function.

  I did all the initialisation correctly. I didn’t forget the avcodec_register_all() and av_init_packet() functions.

  Here is the code for initialisation :

    _c = NULL;
  
    _frame_nb = 0;
  
  
  
    // Register all formats and codecs
  
    #pragma omp critical
  
    {
  
        avcodec_register_all();
  
    }
  
  
  
    _pkt = new AVPacket;
  
    av_init_packet(_pkt);  // a defaut de pouvoir ecrire : pkt = av_packet_alloc();
  
  
  
    if(!_pkt)
  
        exit(1);
  
  
  
      _codec = avcodec_find_encoder_by_name("libx264rgb");
  
  
  
    if (!_codec) {
  
        fprintf(stderr, "codec not found\n");
  
        exit(1);
  
    }
  
  
  
    _c = avcodec_alloc_context3(_codec);
  
    if (!_c) {
  
        fprintf(stderr, "Could not allocate video codec context\n");
  
        exit(1);
  
    }
  
  
  
    _c->debug = true;
  
    _c->pix_fmt =  (AVPixelFormat)AV_PIX_FMT_RGB24;
  
    _c->width = this->_headerCam[this->_currentCam]->iNbCol;
  
    _c->height = this->_headerCam[this->_currentCam]->iNbLine;
  
  
  
    _picture = av_frame_alloc();
  
    if (!_picture) {
  
        fprintf(stderr, "Could not allocate video _picture\n");
  
        exit(1);
  
    }
  
  
  
    _tmp_picture = av_frame_alloc();
  
    if (!_tmp_picture) {
  
        fprintf(stderr, "Could not allocate video _tmp_picture\n");
  
        exit(1);
  
    }
  
  
  
  
  
        _tmp_picture->format = (AVPixelFormat)AV_PIX_FMT_RGB24;
  
        _tmp_picture->width = this->_headerCam[this->_currentCam]->iNbCol;
  
        _tmp_picture->height = this->_headerCam[this->_currentCam]->iNbLine;
  
        _tmp_picture->linesize[0] = this->_headerCam[this->_currentCam]->iNbCol;
  
  
  
    /* open it */
  
    if (avcodec_open2(_c, _codec, NULL) < 0) {
  
        fprintf(stderr, "could not open codec\n");
  
        exit(1);
  
    }

  And the decode function :

          _pkt->data = NULL;    // packet data will be allocated by the encoder
  
          _pkt->size = 0;
  
  
  
          unsigned char * inbuf;
  
          inbuf = (uint8_t*)av_malloc(w*h*3);
  
  
  
          //! read img size
  
          int size_img;
  
          fread(&size_img, sizeof(int), 1, this->_pFile);
  
          _pkt->size = fread(inbuf, 1, size_img, this->_pFile);
  
  
  
          _pkt->data = (unsigned char*)inbuf;
  
  
  
          if(_pkt->size)
  
          {
  
              len = avcodec_decode_video2(_c, _tmp_picture, &got_picture, _pkt);
  
              ...
  
          }

  Any idea ?

• A newbie Struggling with FFmpeg Video Encoding

  19 avril 2014, par iJose

  From last 1 week i have been struggling with FFmpeg video encoding.
  I am capturing the video from the device camera using UIImagePickerController.
  and the encoding it using the following function.

  After Encoding i am not able to save the video to my device camera roll.

  i used UIVideoAtPathIsCompatibleWithSavedPhotosAlbum(filepath) it returns Zero GOD KNOWS WHY

   +(void)videoEncoder:(NSString *)filename
  
  {
  
      avcodec_register_all();
  
      int codec_id = AV_CODEC_ID_MPEG4;
  
      AVCodec *codec;
  
      AVCodecContext *c= NULL;
  
      int i, ret, x, y, got_output;
  
      FILE *f;
  
      AVFrame *frame;
  
      AVPacket pkt;
  
      uint8_t endcode[] = { 0, 0, 1, 0xb7 };
  
  
  
      printf("Encode video file %s\n", [filename UTF8String]);
  
  
  
      /* find the mpeg1 video encoder */
  
      codec = avcodec_find_encoder(codec_id);
  
      if (!codec) {
  
          fprintf(stderr, "Codec not found\n");
  
          exit(1);
  
      }
  
  
  
      c = avcodec_alloc_context3(codec);
  
      if (!c) {
  
          fprintf(stderr, "Could not allocate video codec context\n");
  
          exit(1);
  
      }
  
  
  
      /* put sample parameters */
  
      c->bit_rate = 400000;
  
      /* resolution must be a multiple of two */
  
      c->width = 352;
  
      c->height = 288;
  
      /* frames per second */
  
      c->time_base= (AVRational){1,25};
  
      c->gop_size = 10; /* emit one intra frame every ten frames */
  
      c->max_b_frames=1;
  
      c->pix_fmt = AV_PIX_FMT_YUV420P;
  
  
  
      if(codec_id == AV_CODEC_ID_MPEG4)
  
          av_opt_set(c->priv_data, "preset", "slow", 0);
  
  
  
      /* open it */
  
      if (avcodec_open2(c, codec, NULL) < 0) {
  
          fprintf(stderr, "Could not open codec\n");
  
          exit(1);
  
      }
  
  
  
      f = fopen([filename UTF8String], "wb");
  
      if (!f)
  
      {
  
          fprintf(stderr, "Could not open %s\n", [filename UTF8String]);
  
          exit(1);
  
      }
  
  
  
      frame = av_frame_alloc();
  
      if (!frame) {
  
          fprintf(stderr, "Could not allocate video frame\n");
  
          exit(1);
  
      }
  
      frame->format = c->pix_fmt;
  
      frame->width  = c->width;
  
      frame->height = c->height;
  
  
  
      /* the image can be allocated by any means and av_image_alloc() is
  
       * just the most convenient way if av_malloc() is to be used */
  
      ret = av_image_alloc(frame->data, frame->linesize, c->width, c->height,
  
                           c->pix_fmt, 32);
  
      if (ret < 0) {
  
          fprintf(stderr, "Could not allocate raw picture buffer\n");
  
          exit(1);
  
      }
  
  
  
      /* encode 1 second of video */
  
      for(i=0;i<25;i++) {
  
          av_init_packet(&pkt);
  
          pkt.data = NULL;    // packet data will be allocated by the encoder
  
          pkt.size = 0;
  
  
  
          fflush(stdout);
  
          /* prepare a dummy image */
  
          /* Y */
  
          for(y=0;yheight;y++) {
  
              for(x=0;xwidth;x++) {
  
                  frame->data[0][y * frame->linesize[0] + x] = x + y + i * 3;
  
              }
  
          }
  
  
  
          /* Cb and Cr */
  
          for(y=0;yheight/2;y++) {
  
              for(x=0;xwidth/2;x++) {
  
                  frame->data[1][y * frame->linesize[1] + x] = 128 + y + i * 2;
  
                  frame->data[2][y * frame->linesize[2] + x] = 64 + x + i * 5;
  
              }
  
          }
  
  
  
          frame->pts = i;
  
  
  
          /* encode the image */
  
          ret = avcodec_encode_video2(c, &pkt, frame, &got_output);
  
          if (ret < 0) {
  
              fprintf(stderr, "Error encoding frame\n");
  
              exit(1);
  
          }
  
  
  
          if (got_output) {
  
              printf("Write frame %3d (size=%5d)\n", i, pkt.size);
  
              fwrite(pkt.data, 1, pkt.size, f);
  
              av_free_packet(&pkt);
  
          }
  
      }
  
  
  
      /* get the delayed frames */
  
      for (got_output = 1; got_output; i++) {
  
          fflush(stdout);
  
  
  
          ret = avcodec_encode_video2(c, &pkt, NULL, &got_output);
  
          if (ret < 0) {
  
              fprintf(stderr, "Error encoding frame\n");
  
              exit(1);
  
          }
  
  
  
          if (got_output) {
  
              printf("Write frame %3d (size=%5d)\n", i, pkt.size);
  
              fwrite(pkt.data, 1, pkt.size, f);
  
              av_free_packet(&pkt);
  
          }
  
      }
  
  
  
      /* add sequence end code to have a real mpeg file */
  
      fwrite(endcode, 1, sizeof(endcode), f);
  
      fclose(f);
  
  
  
      avcodec_close(c);
  
      av_free(c);
  
      av_freep(&frame->data[0]);
  
      av_frame_free(&frame);
  
      printf("\n");
  
  }

• QtAV render in a widget crashes on application close

  23 novembre 2017, par user3606329

  I compiled FFmpeg statically + QtAV statically and QT statically.

  Once I add the QtAV player in a QWidget it crashes on application close. Did I miss any cleanup procdure ?

  MainWindow::MainWindow(QWidget *parent) :
  
      QMainWindow(parent),
  
      ui(new Ui::MainWindow)
  
  {
  
      ui->setupUi(this);
  
      QtAV::setLogLevel(QtAV::LogAll);
  
  
  
  
  
      AVPlayer *player = new AVPlayer();
  
      WidgetRenderer *renderer = new WidgetRenderer();
  
      renderer->show();
  
      player->addVideoRenderer(renderer);
  
      player->setFile("C:\\abc.mp4");
  
      ui->verticalLayout->addWidget(renderer->widget()); # will cause crash on exit. 
  
      player->play();
  
  
  
  }
  
  
  
  MainWindow::~MainWindow()
  
  {
  
    //  delete player; # I tried this and also the removal of the widget
  
   //   delete renderer; # It still does crash 
  
      delete ui;
  
  }

  The crash comes from

  WidgetRenderer *renderer = new WidgetRenderer();

  Once the renderer is embedded in a QWidget the application can’t exit gracefully somehow.

  I already tried to clean it up, remove the widget, delete the object, etc. but the crash still remains.

  The player works great and plays the videos ! It only gives a crash when the application is closed. (Doesn’t exit gracefully somehow).

  The QtAV log does not print anything about it.