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• FFmpeg os.system commands not working but work in Terminal

  28 janvier 2020, par Oscar Dolloway

  I’ve downloaded ffmpeg through the website and ran some commands through the terminal to confirm its install.

  when running the command ’ffmpeg’ in the Terminal it returns

   ffmpeg version 4.2.2 Copyright (c) 2000-2019 the FFmpeg 
  
   developers
  
   built with Apple LLVM version 10.0.0 (clang-1000.11.45.5)

  if i type into Python

  import os
  
  os.system ('ffmpeg')

  it returns

   os.system ('ffmpeg')
  
   sh: ffmpeg: command not found
  
   Out[25]: 32512

  any ideas ?

  Solution :

   ffmpeg = '/bin/ffmpeg' #path to the binary file
  
  
  
   os.system(ffmpeg)

  Output :

  os.system (ffmpeg)
  
  ffmpeg version 4.2.2 Copyright (c) 2000-2019 the FFmpeg developers
  
  built with Apple LLVM version 10.0.0 (clang-1000.11.45.5)

• 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);
  
      }

• 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.