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• Loop a song for a certain amount of time using FFMPEG

  10 avril 2017, par Eduardo Perez

  So, I am trying to loop a song from a video game for one hour, using FFMPEG on Linux or in Windows 10 Bash. I have 3 versions of the song, they are as follows :

  1.Full song in OGG format with LOOPSTART and LOOPLENGTH metadata.
  
  2.Same song in OGG format, except only the segment before LOOPSTART.
  
  3.Same song in OGG format, except only the segment from LOOPSTART to LOOPSTART+LOOPLENGTH.

  So, what I want to do is use either the full song file for the loop, which I don’t think FFMPEG supports, or use the files for the beginning and looping portions of the song. Basically, I want to have FFMPEG create a song which starts off with the beginning segment of the song and loops the looping segment indefinitely until an hour has been played. If possible, I also want a second command so I can add an image or an MP4 video to be shown in a loop while the song is being played, but in the case of a video being used to be shown while the song is played, the music from that video won’t be merged with the music from the song. What command should I use for this ?

• FFmpeg stream dynamic png

  13 avril 2017, par Azarus

  I would like to know if its possible to stream a png or any kind of image using ffmpeg. I would like to generate the image contiously using nodejs that updates every 10 seconds. I would like to display game stats with this in a corner and mix it with some background music or pre recorded commentary on it. Additionaly i would like to mix a video and the image should act like an overlay.

  I am also not sure if using a transparent png image its possible to do

  I couldn’t get my head around doing the mixing with ffmpeg and its looks very complicated so i would like to get some help on it.

  I have video files stored in a folder that i would like to continously stream and mix different music and an image on it. I would like to have it all continously working without stopping the stream.

  Is it possible with ffmpeg cli on linux or i cant avoid using a desktop windows pc for such thing ?

• FFMPEG and DirectX Capture in C++

  13 décembre 2016, par tankyx

  I have a system that allows me to capture a window and save it as a mp4, using ffmpeg. I use gdigrab to capture the frame, but it is fairly slow (60ms per av_read_frame calls)

  I know I can capture a game using the DirectX API, but I don’t know how to convert the resulting BMP to an AVFrame.

  The following code is the DirectX code I use to capture the frame

  extern void* pBits;
  
  extern IDirect3DDevice9* g_pd3dDevice;
  
  IDirect3DSurface9* pSurface;
  
  g_pd3dDevice->CreateOffscreenPlainSurface(ScreenWidth, ScreenHeight,
  
                                        D3DFMT_A8R8G8B8, D3DPOOL_SCRATCH, 
  
                                        &pSurface, NULL);
  
  g_pd3dDevice->GetFrontBufferData(0, pSurface);
  
  D3DLOCKED_RECT lockedRect;
  
  pSurface->LockRect(&lockedRect,NULL,
  
                 D3DLOCK_NO_DIRTY_UPDATE|
  
                 D3DLOCK_NOSYSLOCK|D3DLOCK_READONLY)));
  
  for( int i=0 ; i < ScreenHeight ; i++)
  
  {
  
      memcpy( (BYTE*) pBits + i * ScreenWidth * BITSPERPIXEL / 8 , 
  
           (BYTE*) lockedRect.pBits + i* lockedRect.Pitch , 
  
           ScreenWidth * BITSPERPIXEL / 8);
  
  }
  
  g_pSurface->UnlockRect();
  
  pSurface->Release();

  And here is my read loop :

  {
  
      while (1) {
  
      if (av_read_frame(pFormatCtx, &packet) < 0 || exit)
  
          break;
  
      if (packet.stream_index == videoindex) {
  
          // Decode video frame
  
          av_packet_rescale_ts(&packet, { 1, std::stoi(pParser->GetVal("video-fps")) }, pCodecCtx->time_base);
  
          avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);
  
  
  
          if (frameFinished) {
  
              pFrame->pts = i;
  
              i++;
  
              sws_scale(sws_ctx, (uint8_t const * const *)pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pFrameRGB->data, pFrameRGB->linesize);
  
              pFrameRGB->pts = pFrame->pts;
  
              enc.encodeFrame(pFrameRGB);
  
  
  
      }
  
      // Free the packet that was allocated by av_read_frame
  
      av_free_packet(&packet);
  
  }

  How can I create an AVFrame using the bmp I have, without using the av_read_frame ?