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• ffmpeg : Infinite length output when overlaying subtitles onto black image

  18 juillet 2020, par rosuav

  I'm trying to do some analysis of image-based subtitles by outputting them as a sequence of PNGs to a pipe. My command line looks like this :

  


  ffmpeg -y -i $INPUTFILE -f lavfi -i color=c=black:s=1920x1080 -filter_complex "[1:v][0:s:5]overlay[v]" -shortest -map "[v]" -c:v png -f image2pipe - | pike subspng.pike


  


  In theory, -shortest should mean that the stream stops at the shortest input, which would be roughly seven minutes of input file. Instead, my script receives an infinite sequence of black frames after the last frame of subtitles, until I send FFMPEG a SIGINT. Placing -shortest before -filter_complex has the same effect.

  


  Is there a different way to force the filtering to stop at the end of the input file ?

  


  EDIT : Using the shortest=1 flag on the overlay filter also doesn't help, even in combination with -shortest.

  


• Ffmpeg to OpenGL texture black screen

  23 janvier 2014, par user3177342

  I am trying to make textures from ffmpeg source, but I get the black screen.

  here is the code

  avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished,
  
              &packet);
  
  
  
          // Did we get a video frame?
  
          if(frameFinished)
  
          {
  
           f++;
  
  
  
                  pFrameRGB=avcodec_alloc_frame();
  
                  struct SwsContext* swsContext = sws_getContext(pCodecCtx->width, pCodecCtx->height,
  
                          pCodecCtx->pix_fmt,
  
                          pCodecCtx->width, pCodecCtx->height, AV_PIX_FMT_RGB24, SWS_BICUBIC,
  
                          NULL, NULL, NULL);
  
                  if (swsContext == NULL) {
  
                   fprintf(stderr, "Cannot initialize the conversion context!\n");
  
                    exit(1);
  
                    };
  
  
  
  
  
                  sws_scale(swsContext, pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pFrameRGB->data, pFrameRGB->linesize);
  
                  glGenTextures(1, &VideoTexture);
  
                  glBindTexture(GL_TEXTURE_2D, VideoTexture);
  
                  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  
                  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  
                  glTexImage2D(GL_TEXTURE_2D, 0, 3, pCodecCtx->width, pCodecCtx->height, 0, GL_RGB, GL_UNSIGNED_BYTE, pFrameRGB->data[0]);
  
   }
  
  }
  
  
  
  // Free the packet that was allocated by av_read_frame
  
  av_free_packet(&packet);
  
  if (f>1) break;

  Strangerly when I draw i get black screen, my video is not black.

  if (VideoTexture != 0)
  
      {
  
          glEnable(GL_TEXTURE_2D);
  
          glPushMatrix();
  
          glBindTexture(GL_TEXTURE_2D, VideoTexture);
  
          glBegin(GL_QUADS);
  
          glTexCoord2i(0, 0); glVertex2i(0, 0);
  
          glTexCoord2i(1, 0); glVertex2i(Width, 0);
  
          glTexCoord2i(1, 1); glVertex2i(Width, Height);
  
          glTexCoord2i(0, 1); glVertex2i(0, Height);
  
          glEnd();
  
          glPopMatrix();
  
          glDisable(GL_TEXTURE_2D);
  
      }

• Merge "Add zero offset checking in SSE2 sub-pixel filter function"

  8 mars 2011, par Yunqing Wang

  Merge "Add zero offset checking in SSE2 sub-pixel filter function"