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• ffmpeg moving text drawtext

  5 juillet 2021, par BOB

  I'm using ffmpeg library to draw text on video in specific time and i'm success to do that Now i need to move the text from position to another and i can't do that so can any one suggest me how to do that

  



  i'm using this command to move text from top to down but i can't determine the x and Y to move from the x,y to specific x,y

  



  ffmpeg -i VideoInput.mp4 -vf "drawtext=enable='between(t,12,14)':fontfile=myfont.otf:text='Test test':x=(w-text_w)/2:y=w/50\*mod(t\,2):fontsize=65" -acodec copy outputVideo.mp4


  


• Display ffmpeg frames on opgel texture

  24 octobre 2014, par naki

  I am using Dranger tutorial01 (ffmpeg) to decode the video and get AVI frames. I want to use OpenGL to display the video.

  http://dranger.com/ffmpeg/tutorial01.html

  The main function is as follows :

  int main (int argc, char** argv) {
  
  // opengl stuff
  
  glutInit(&argc, argv);
  
  glutInitDisplayMode(GLUT_RGBA);
  
  glutInitWindowSize(800, 600);
  
  glutCreateWindow("Hello GL");
  
  
  
  glutReshapeFunc(changeViewport);
  
  glutDisplayFunc(render);
  
  
  
  GLenum err = glewInit();
  
  if(GLEW_OK !=err){
  
      fprintf(stderr, "GLEW error");
  
      return 1;
  
  }
  
  
  
  glClear(GL_COLOR_BUFFER_BIT);
  
  
  
  
  
  glEnable(GL_TEXTURE_2D);
  
  GLuint texture;
  
  glGenTextures(1, &texture); //Make room for our texture
  
  glBindTexture(GL_TEXTURE_2D, texture);
  
  
  
  //ffmpeg stuff
  
  
  
   AVFormatContext *pFormatCtx = NULL;
  
   int             i, videoStream;
  
   AVCodecContext  *pCodecCtx = NULL;
  
   AVCodec         *pCodec = NULL;
  
   AVFrame         *pFrame = NULL; 
  
   AVFrame         *pFrameRGB = NULL;
  
   AVPacket        packet;
  
   int             frameFinished;
  
   int             numBytes;
  
   uint8_t         *buffer = NULL;
  
  
  
   AVDictionary    *optionsDict = NULL;
  
  
  
  
  
   if(argc < 2) {
  
  printf("Please provide a movie file\n");
  
  return -1;
  
   }
  
   // Register all formats and codecs
  
  
  
  av_register_all();
  
  
  
   // Open video file
  
   if(avformat_open_input(&pFormatCtx, 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, argv[1], 0);
  
  
  
  // Find the first video stream
  
  
  
  videoStream=-1;
  
   for(i=0; inb_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) {
  
     fprintf(stderr, "Unsupported codec!\n");
  
     return -1; // Codec not found
  
   }
  
   // Open codec
  
  if(avcodec_open2(pCodecCtx, pCodec, &optionsDict)<0)
  
     return -1; // Could not open codec
  
  
  
   // 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(PIX_FMT_RGB24, pCodecCtx->width,
  
                pCodecCtx->height);
  
   buffer=(uint8_t *)av_malloc(numBytes*sizeof(uint8_t));
  
  
  
  struct SwsContext      *sws_ctx = sws_getContext(pCodecCtx->width,
  
             pCodecCtx->height, pCodecCtx->pix_fmt, 800,
  
             600, PIX_FMT_RGB24, SWS_BICUBIC, NULL,
  
             NULL, NULL);
  
  
  
  
  
   // 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, PIX_FMT_RGB24,
  
       pCodecCtx->width, pCodecCtx->height);
  
  
  
   // Read frames and save first five frames to disk
  
   i=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) {
  
  // Convert the image from its native format to RGB
  
    /*  sws_scale
  
      (
  
          sws_ctx,
  
          (uint8_t const * const *)pFrame->data,
  
          pFrame->linesize,
  
          0,
  
          pCodecCtx->height,
  
          pFrameRGB->data,
  
          pFrameRGB->linesize
  
      );
  
     */
  
  sws_scale(sws_ctx, pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pFrameRGB->data, pFrameRGB->linesize);
  
    // additional opengl
  
      glBindTexture(GL_TEXTURE_2D, texture);
  
  
  
          //gluBuild2DMipmaps(GL_TEXTURE_2D, 3, pCodecCtx->width, pCodecCtx->height, GL_RGB, GL_UNSIGNED_INT, pFrameRGB->data[0]);
  
     // glTexSubImage2D(GL_TEXTURE_2D, 0, 0,0, 840, 460, GL_RGB, GL_UNSIGNED_BYTE, pFrameRGB->data[0]);
  
  
  
          glTexImage2D(GL_TEXTURE_2D,                //Always GL_TEXTURE_2D
  
              0,                            //0 for now
  
              GL_RGB,                       //Format OpenGL uses for image
  
              pCodecCtx->width, pCodecCtx->height,  //Width and height
  
              0,                            //The border of the image
  
              GL_RGB, //GL_RGB, because pixels are stored in RGB format
  
              GL_UNSIGNED_BYTE, //GL_UNSIGNED_BYTE, because pixels are stored
  
                              //as unsigned numbers
  
              pFrameRGB->data[0]);               //The actual pixel data
  
    // additional opengl end   
  
  
  
  // Save the frame to disk
  
  if(++i<=5)
  
    SaveFrame(pFrameRGB, pCodecCtx->width, pCodecCtx->height, 
  
          i);
  
    }
  
  }
  
  
  
  glColor3f(1,1,1);
  
  glBindTexture(GL_TEXTURE_2D, texture);
  
  glBegin(GL_QUADS);
  
      glTexCoord2f(0,1);
  
      glVertex3f(0,0,0);
  
  
  
      glTexCoord2f(1,1);
  
      glVertex3f(pCodecCtx->width,0,0);
  
  
  
      glTexCoord2f(1,0);
  
      glVertex3f(pCodecCtx->width, pCodecCtx->height,0);
  
  
  
      glTexCoord2f(0,0);
  
      glVertex3f(0,pCodecCtx->height,0);
  
  
  
  glEnd();
  
  // Free the packet that was allocated by av_read_frame
  
  av_free_packet(&packet);
  
   }
  
  
  
  
  
    // Free the RGB image
  
   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);
  
  
  
   return 0;
  
  }

  Unfortunately i could not find my solution here

  ffmpeg video to opengl texture

  The program compiles but does not show any video on the texture. Just a OpenGL window is created.

• Using decibel values, how to detect if the user is talking or silent ?

  26 juin 2021, par Nadir Abbas

  I have used FFMPEG to extract decibel (or rms ? I am not familiar with the units) values of the audio volume from an mp4. I have 20 samples per frame.

  


  

  


  How can I use these values (which are negative in almost all frames), to determine if the frame is silent or has audio (music, speech, etc) ?