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• Render FFmpeg AVFrame as OpenGL texture ?

  5 mars 2019, par ZeroDefect

  I’m attempting to to render a jpeg image (1024x1024 pixels) in the form of an FFmpeg AVFrame as a texture in OpenGL. What I get instead is something that appears as a 1024x1024 dark green quad :

  

  The code to render the AVFrame data in OpenGL is shown below. I have convinced myself that the raw RGB data held within the FFmpeg AVFrame data is not solely dark green.

  GLuint g_texture = {};
  
  
  
  //////////////////////////////////////////////////////////////////////////
  
  void display()
  
  {
  
      // Clear color and depth buffers
  
      glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  
      glMatrixMode(GL_MODELVIEW);     // Operate on model-view matrix
  
  
  
      glEnable(GL_TEXTURE_2D);
  
      GLuint texture = g_texture;
  
      glBindTexture(GL_TEXTURE_2D, texture);
  
  
  
      // Draw a quad
  
      glBegin(GL_QUADS);
  
      glVertex2i(0, 0); // top left
  
      glVertex2i(1024, 0); // top right
  
      glVertex2i(1024, 1024); // bottom right
  
      glVertex2i(0, 1024); // bottom left
  
      glEnd();
  
  
  
      glDisable(GL_TEXTURE_2D);
  
      glBindTexture(GL_TEXTURE_2D, 0);
  
  
  
      glFlush();
  
  }
  
  
  
  /* Initialize OpenGL Graphics */
  
  void initGL(int w, int h)
  
  {
  
      glViewport(0, 0, w, h); // use a screen size of WIDTH x HEIGHT
  
      glEnable(GL_TEXTURE_2D);     // Enable 2D texturing
  
  
  
      glMatrixMode(GL_PROJECTION);     // Make a simple 2D projection on the entire window
  
      glOrtho(0.0, w, h, 0.0, 0.0, 100.0);
  
      glMatrixMode(GL_MODELVIEW);    // Set the matrix mode to object modeling
  
      //glTranslatef( 0, 0, -15 );
  
  
  
      glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
  
      glClearDepth(0.0f);
  
      glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear the window
  
  }
  
  
  
  //////////////////////////////////////////////////////////////////////////
  
  int main(int argc, char *argv[])
  
  {
  
      std::shared_ptr<avframe> apAVFrame;
  
      if (!load_image_to_AVFrame(apAVFrame, "marble.jpg"))
  
      {
  
          assert(false);
  
          return 1;
  
      }
  
  
  
      // From here on out, the AVFrame is RGB interleaved
  
      // and is sized to 1,024 x 1,024 (power of 2).
  
  
  
      glutInit(&amp;argc, argv);
  
      glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);
  
      glutInitWindowSize(1060, 1060);
  
      glutInitWindowPosition(0, 0);
  
      glutCreateWindow("OpenGL - Creating a texture");
  
  
  
      glGenTextures(1, &amp;g_texture);
  
  
  
      //glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
  
      glBindTexture(GL_TEXTURE_2D, g_texture);
  
      glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, apAVFrame->width,
  
                   apAVFrame->height, 0, GL_RGB, GL_UNSIGNED_BYTE,
  
                   apAVFrame->data[0]);
  
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); /* We will use linear interpolation for magnification filter */
  
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); /* We will use linear interpolation for minifying filter */
  
  
  
      initGL(1060, 1060);
  
  
  
      glutDisplayFunc(display);
  
  
  
      glutMainLoop();
  
  
  
      return 0;
  
  }
  
  </avframe>

  Environment :

  • Ubuntu 18.04
  • GCC v8.2

  EDIT : As per @immibis’ suggestion below, it all works when I change the rendering of the quad to :

  // Draw a quad
  
  glBegin(GL_QUADS);
  
  glTexCoord2f(0, 0);
  
  glVertex2i(0, 0); // top left
  
  glTexCoord2f(1, 0);
  
  glVertex2i(1024, 0); // top right
  
  glTexCoord2f(1, 1);
  
  glVertex2i(1024, 1024); // bottom right
  
  glTexCoord2f(0, 1);
  
  glVertex2i(0, 1024); // bottom left
  
  glEnd();

• FFMPEG to OpenGL Texture

  23 avril 2014, par Spamdark

  I was here to ask, how can I convert an AVFrame to an opengl texture. Actually, I created a renderer the outputs me the audio (Audio is working) and the video, but the video is not outputing. Here is my code :

  Texture creation :

  glGenTextures(1,&_texture);
  
  glBindTexture(GL_TEXTURE_2D,_texture);
  
  glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
  
  
  
  glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR ); 
  
  glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );

  Code Info : _texture variable is a GLuint that keeps the texture ID

  Function that gets the AVFrame and convert it to OpenGL Texture :

  int VideoGL::NextVideoFrame(){
  
  // Get a packet from the queue
  
  AVPacket *videopacket = this->DEQUEUE(VIDEO);
  
  int frameFinished;
  
  if(videopacket!=0){
  
      avcodec_decode_video2(_codec_context_video, _std_frame,&frameFinished,videopacket);
  
  
  
      if(frameFinished){
  
  
  
          sws_scale(sws_ctx, _std_frame->data, _std_frame->linesize, 0, _codec_context_video->height, _rgb_frame->data, _rgb_frame->linesize);
  
  
  
          if(_firstrendering){
  
          glBindTexture(GL_TEXTURE_2D,_texture);
  
          glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, _codec_context_video->width,_codec_context_video->height,0,GL_RGB,GL_UNSIGNED_BYTE,_rgb_frame->data[0]);
  
  
  
          _firstrendering = false;
  
  
  
          }else{
  
  
  
              glActiveTexture(_texture);
  
              glBindTexture(GL_TEXTURE_2D,_texture);
  
              glTexSubImage2D(GL_TEXTURE_2D,0,0,0,_codec_context_video->width,_codec_context_video->height,GL_RGB,GL_UNSIGNED_BYTE,_rgb_frame->data[0]);
  
  
  
          }
  
          av_free_packet(videopacket);
  
          return 0;
  
      }else{
  
  
  
          av_free_packet(videopacket);
  
          return -1;
  
      }
  
  
  
  }else{
  
      return -1;
  
  }
  
  return 0;
  
  }

  Code Information : There is a queue where a thread store the AVFrames, this function is frequently called to get the AVFrames, until it gets a NULL it stops to being called.

  That’s actually not working. (I tried to look at some questions in stack overflow, it’s still not working)
  Any example, or someone that helps me to correct any error there ?

  Additional Data : I tried to change the GL_RGB to GL_RGBA and started to play with the formats, anyway it crashes when I try GL_RGBA (Because the width and height are very big, anyway I tried to resize them). I have tried to change the sizes to Power Of 2, stills not working.

  1 Edit :

  Thread function :

  DWORD WINAPI VideoGL::VidThread(LPVOID myparam){
  
  
  
  VideoGL * instance = (VideoGL*) myparam;
  
  instance->wave_audio->Start();
  
  
  
  int quantity=0;
  
  
  
  AVPacket packet;
  
  while(av_read_frame(instance->_format_context,&packet) >= 0){
  
      if(packet.stream_index==instance->videoStream){
  
          instance->ENQUEUE(VIDEO,&packet);
  
      }
  
      if(packet.stream_index==instance->audioStream){
  
          instance->ENQUEUE(AUDIO,&packet);
  
      }
  
  }
  
  
  
  instance->ENQUEUE(AUDIO,NULL);
  
  instance->ENQUEUE(VIDEO,NULL);
  
  
  
  return 0;
  
  }

  Thread creation function :

  CreateThread(NULL, 0, VidThread, this, NULL, NULL);

  Where this refers to the class that contains the NextVideoFrame, and the _texture members.

  Solved :

  I followed some of the datenwolf tips, and now the video is displaying correctly with the audio/video :

  

• Is there a way to eliminate seek time when decoding part of a video using ffmpeg ?

  17 décembre 2019, par Babis

  I’ve got some MKV videos encoded with FFV1. For each of the frames, I want to run some complex and time-intensive python or matlab code, so I’m using multithreading, where each thread works on an individual image.

  I’ve tried extracting a single frame from the video using -ss, but it’s terribly inefficient.

  The most efficient way is to decompress everything into images in one go, but then I’m writing to disk, and then I’ll be reading from disk, therefore it’s not ideal either.

  I’ve tried using a ram disk to export images to, and reading them from python/matlab, but it’s not great performance-wise either. Also, I have to split the export into several batches, as the video file is 20GB and all of the exported images will not fit into memory

  Is there a way to rapidly extract individual frames from ffmpeg directly into RAM (or ram disk), so that they can be used by another program ? For example using something like a lookup-table.

  For reference, each video is about 20GB, comprised of 50000 frames, and they are all keyframes (it’s for archival purposes)