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• ValueError When Reading Video Frame

  28 juin 2017, par Bassie

  I am following this article, from where I got this code :

  FFMPEG_BIN ="Z:\ffmpeg\bin\ffmpeg.exe"
  
  
  
  import subprocess as sp
  
  command = [ FFMPEG_BIN,
  
              '-i', 'video.mp4',
  
              '-f', 'image2pipe',
  
              '-pix_fmt', 'rgb24',
  
              '-vcodec', 'rawvideo', '-']
  
  pipe = sp.Popen(command, stdout = sp.PIPE, bufsize=10**8, shell=True)
  
  
  
  import numpy
  
  # read 420*360*3 bytes (= 1 frame)
  
  raw_image = pipe.stdout.read(420*360*3)
  
  # transform the byte read into a numpy array
  
  image =  numpy.fromstring(raw_image, dtype='uint8')
  
  image = image.reshape((360,420,3))
  
  # throw away the data in the pipe's buffer.
  
  pipe.stdout.flush()

  When I run it I see this error :

  Traceback (most recent call last):
  
    File "Z:\py\ffmtest\test.py", line 16, in <module>
  
      image = image.reshape((360,420,3))
  
  ValueError: total size of new array must be unchanged
  
  </module>

  Where line 16 is image = image.reshape((360,420,3)). I think this error is produced by numpy, but probably because I am calculating the values for my video incorrectly.

  Output :

  raw_image : b’ ’

  len(raw_image) : 0

  image : [ ]

  len(image) : 0

  I am not sure whether I am passing in the correct values for read or reshape functions - any help at all is much appreciated !

• ffmpeg Unrecognized option 'hls_enc'

  16 juin 2017, par riubin

  Does anyone have a ffmpeg problem that Unrecognized option ’hls_enc’ ?

  when I use ffmpeg to convert videos to hls with option ’hls_enc’,followed the document : https://www.ffmpeg.org/ffmpeg-formats.html#Options-5
  but throw error:Unrecognized option ’hls_enc’

  Is it missing any configure options ?

  configuration : —enable-gpl —enable-nonfree —yasmexe=/data/ffmpeg.src/_release/bin/yasm —prefix=/data/ffmpeg.src/_release —cc= —enable-static —disable-shared —enable-debug —extra-cflags=’-I/data/ffmpeg.src/_release/include’ —extra-ldflags=’-L/data/ffmpeg.src/_release/lib -lm -ldl’ —enable-postproc —enable-bzlib —enable-zlib —enable-parsers —enable-pthreads —enable-libx264 —enable-libmp3lame —enable-libfdk_aac —enable-libspeex —extra-libs=-lpthread —enable-encoders —enable-decoders —enable-avfilter —enable-muxers —enable-demuxers

• Some bugs when using SDL2 and ffmpeg to make a video player

  1er juin 2017, par trycatch

  used sws_scale to resize the image, and SDL2.0 to render, pixel format is YUV420P.

  1.When I Create SDL Render with SDL_RENDERER_SOFTWARE, I Get a black image like this :enter image description here, the top-left corner has a green point ;
  But When I Create SDL Render with SDL_RENDERER_ACCELERATED, I can See normal image ;

  2.When I resize the window, the player will crash on SDL_UpdateYUVTexture. I check width, height and linesize of the data, everything is OK.

  WHY ?

  Key Code :

  if (swscale_.frame.width % 2) 
  
    swscale_.frame.width -= 1;
  
  
  
  swscale_.free();
  
  swscale_.context = sws_getContext(
  
          vcodec->width, vcodec->height, vcodec->pix_fmt,
  
          swscale_.frame.width, swscale_.frame.height,
  
          AV_PIX_FMT_YUV420P, SWS_BICUBIC, nullptr, nullptr, nullptr);
  
  
  
  if (!swscale_.context)
  
      throw std::runtime_error("sws_getContext.");
  
  
  
  if (swscale_.frame.avframe)
  
    av_frame_free(&swscale_.frame.avframe);
  
  swscale_.frame.avframe = av_frame_alloc();
  
  unsigned char* out_buffer = (unsigned char *)av_malloc(av_image_get_buffer_size(AV_PIX_FMT_YUV420P, swscale_.frame.width, swscale_.frame.height, 1)+16);
  
  unsigned char* tmp = &out_buffer[16 - (unsigned long long)out_buffer % 16];
  
  av_image_fill_arrays(swscale_.frame.avframe->data, swscale_.frame.avframe->linesize, tmp,
  
    AV_PIX_FMT_YUV420P, swscale_.frame.width, swscale_.frame.height, 1);
  
  
  
  sws_scale(swscale_.context, (const unsigned char* const*)vframe_->data, vframe_->linesize, 
  
    0, vframe_->height,
  
    swscale_.frame.avframe->data, swscale_.frame.avframe->linesize);
  
  
  
  self.onRenderHandle(swscale_.frame);

  Code of SDL rendering :

  void Player::onRender(const frame& frame)
  
  {
  
    if (sdl_lock_.try_lock()) {
  
      ::ValidateRect(native_window_, NULL);
  
      if (frame.width != scr_width_ || frame.height != scr_height_) {
  
        scr_width_ = frame.width; scr_height_ = frame.height;
  
        SDL_SetWindowSize(screen_, scr_width_ + 2, scr_height_ + 2);
  
        SDL_DestroyRenderer(sdl_renderer_);
  
        sdl_renderer_ = SDL_CreateRenderer(screen_, -1, 0);
  
        video_texture_ = SDL_CreateTexture(sdl_renderer_, SDL_PIXELFORMAT_IYUV,
  
          SDL_TEXTUREACCESS_STREAMING, scr_width_, scr_height_);
  
      }
  
      SDL_UpdateYUVTexture(video_texture_, NULL,
  
        frame.avframe->data[0], frame.avframe->linesize[0],
  
        frame.avframe->data[1], frame.avframe->linesize[1],
  
        frame.avframe->data[2], frame.avframe->linesize[2]);
  
      sdl_lock_.unlock();
  
      ::InvalidateRect(native_window_, NULL, false);
  
    }
  
  }
  
  void Player::onPaint()
  
  {
  
    std::lock_guard lock(sdl_lock_);
  
    SDL_RenderClear(sdl_renderer_);
  
    SDL_RenderCopy(sdl_renderer_, video_texture_, NULL, NULL);
  
    SDL_RenderPresent(sdl_renderer_);
  
  }