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• How to convert an ffmpeg texture to Open GL texture without copying to CPU memory

  19 avril, par PPP

  This ffmpeg example demonstrates how to do hardware decoding : https://github.com/FFmpeg/FFmpeg/blob/release/4.2/doc/examples/hw_decode.c

  



  At line 109 it does this :

  



  /* retrieve data from GPU to CPU */
            if ((ret = av_hwframe_transfer_data(sw_frame, frame, 0)) < 0) {


  



  I want to avoid this because it takes time. Therefore, I need a way to reuse that decoded video, which is in GPU memory, to redo color conversion.

  



  How to transform the decoded texture in GPU memory to texture in Open GL without getting it back to CPU memory like in the code above ?

  



  If the above is not possible, how to do color conversion in the decoded video using open gl ? I heard that ffmpeg supports passing opengl shaders as input, so I guess it's possible.

  


• ffmpeg decoding MP4 to Open GL texture black screen

  5 septembre 2019, par Dakiaiu

  I decoded a MP4 video and want to display the AVFrame via glTexImage2D and glTexSubImage2D but all I get is a blank GL Window.

  I’ve tried looking at the various examples in the ffmpeg github examples tree. https://github.com/FFmpeg/FFmpeg/tree/master/doc/examples and different posts from the past and recently on this site learning slowly from them but I could not find anything I am doing wrong.

  while(av_read_frame(format_context,packet) >= 0){
  
  
  
          if(packet->stream_index == video_stream_index){
  
  
  
              av_frame = decode(codec_context,av_frame,packet);
  
  
  
              sws_context = sws_getContext(codec_context->width,codec_context->height,codec_context->pix_fmt,codec_context->width,codec_context->height,
  
                      AV_PIX_FMT_RGB24, SWS_BICUBIC,nullptr,nullptr,nullptr);
  
  
  
              sws_scale(sws_context,
  
                      av_frame->data,
  
                      av_frame->linesize,
  
                      0,
  
                      codec_context->height,
  
                      gl_frame->data,
  
                      gl_frame->linesize);
  
  
  
              sws_freeContext(sws_context);
  
  
  
              if(first_use == true) {
  
  
  
                  glTexImage2D(GL_TEXTURE_2D,
  
                               0,
  
                               GL_RGB,
  
                               codec_context->width,
  
                               codec_context->height,
  
                               0,
  
                               GL_RGB,
  
                               GL_UNSIGNED_BYTE,
  
                               gl_frame->data[0]);
  
  
  
                  first_use = false;
  
  
  
              }else{
  
  
  
                  glTexSubImage2D(GL_TEXTURE_2D,
  
                          0,
  
                          0,
  
                          0,
  
                          codec_context->width,
  
                          codec_context->height,
  
                          GL_RGB,
  
                          GL_UNSIGNED_BYTE,
  
                          gl_frame->data[0]);
  
  
  
              }
  
  
  
          }
  
  
  
  
  
      }
  
  
  
  
  
      while( glfwGetKey(window, GLFW_KEY_ESCAPE ) != GLFW_PRESS &&
  
             glfwWindowShouldClose(window) == 0 );
  
  
  
  }

  The frames decode successfully but I cannot see anything. It has to be something with the above gl code that I have done wrong. I can show the ffmpeg code above if necessary.

• avcodec/h264 : Fix poc_lsb in open gop context

  23 juillet 2019, par Nicolas Gaullier

  avcodec/h264 : Fix poc_lsb in open gop context
  When no IDR nor mmco_reset is found, prev_poc_lsb is
  
  undefined and shall not be assumed to be zero
  

  • [DH] libavcodec/h264_parse.c
  • [DH] libavcodec/h264dec.c