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• How to insert lots of small looped videos or GIFs in HTML (thousand or more), but keep decent quality and page size ?

  10 novembre 2020, par Armen Avakian

  I need to place a thousand of small GIFs (20x20 pixels or slightly bigger) in the HTML. Almost all of them are visible at once, when page is loaded. There are several ways I tried, but each one has a problem.

  


  Way 1. Placing GIF images. GIFs are inefficient and heavy, so a lot of traffic will be needed to load the page. WEBP is better, but it is not supported fully in recent versions of Safari. So I made GIFs smaller, with low quality. In Safari I am loading this low quality GIFs, in other browsers I load WEBP. And it works nice, but the problem is that with a thousand of small GIFs, a user will need to load more than 600 MB for this page... So this way is... not as good. I can make them even lower in quality, but I don't want to make experience worse. Even now the quality is average.

  


  Way 2. Making MP4 and embedding them into looped video tags with autostart, so they look like a GIF. This way would be AWESOME, because MP4 is much smaller in size, but it keeps good quality. The problem here is when I add even 10-15 small videos in tags, the browser can't manage with it and starts working veeeery slowly. Each video is becoming very slow. So the experience is even worse than with low quality GIFs.

  


  My question is – how to achieve best way in this case, keeping decent quality and low sizes for each video ? Maybe I can use somehow MP4 videos in another way ? Does anyone know how to solve this issue ?

  


  For scaling videos and converting to GIF/WEBP I use ffmpeg.

  


• ffmpeg hangs in avcodec_encode_video2

  3 août 2016, par Иван Чванов

  I encode the video stream using ffmeg. Shell QT Creator. OC Windows 7. The compiler MinGW. H264 codec.

  There is a function, which I give to the input frame, and I must return an encoded byte array. Within this function it hangs when calling avcodec_encode_video2, but not on the first call, and at random.
  That is, an arbitrary coding frame hangs (100 to 10000).

  QByteArray VideoEncoder::createFrameVideoFromImage(QImage picture)
  
  {
  
      AVFrame* frame_source = av_frame_alloc();        
  
      avpicture_fill((AVPicture*)frame_source, picture.bits(), AV_PIX_FMT_RGB24, this->width_frame, this->height_frame);
  
  
  
      AVFrame* frame_dst = av_frame_alloc();
  
  
  
      avpicture_fill((AVPicture*)frame_dst, (uint8_t*)this->inbuffer, AV_PIX_FMT_YUV420P, this->width_frame, this->height_frame);
  
  
  
      sws_scale(this->convert_rgb_yuv, frame_source->data, frame_source->linesize,
  
          0, this->ctx_codec_in->height, frame_dst->data, frame_dst->linesize);
  
  
  
      AVPacket packet;
  
      av_init_packet(&packet);
  
      packet.data = NULL;
  
      packet.size = 0;
  
      packet.pts = packet.dts = AV_NOPTS_VALUE;
  
  
  
      int nOutputSize = 0;
  
      if (avcodec_encode_video2(this->ctx_codec_in, &packet, frame_dst, &nOutputSize) < 0)
  
      {
  
          qDebug() << "VideoEncoder error";
  
      }
  
      this->traffic += packet.size;
  
  
  
      QByteArray data_frame = QByteArray((char*)packet.data, packet.size);
  
  
  
      av_frame_free(&frame_source);
  
      av_frame_free(&frame_dst);
  
      av_free_packet(&packet);
  
  
  
      return data_frame;
  
  }

  Thank you in advance !

• Streaming live video from webcam and displaying in VLC

  17 septembre 2017, par Robert

  I have webcam connected to the computer. This camera is detected by ffmpeg.
  This command works correctly :

  ffmpeg -f dshow -i video="Integrated Webcam" out6.mp4

  I can display out6.mp4 file in VLC. But I want to display video in VLC directly from webcam using ffmpeg. So I’ve invoke such a command :

  ffmpeg -f dshow -i video="Integrated Webcam" -preset ultrafast -vcodec libx264 -tune zerolatency -b 900k -f mpegts udp://192.168.0.11:1234/

  and in VLC I enter address udp ://192.168.0.11:1234/ in Open streaming network but the video doesn’t display. I only see traffic bollard.
  In cmd I see that everythink works correctly :

  frame= 1753 fps= 20 q=35.0 size=    7257kB time=00:01:26.63 bitrate= 686.2kbits/
  
  frame= 1766 fps= 20 q=35.0 size=    7305kB time=00:01:27.13 bitrate= 686.8kbits/
  
  frame= 1778 fps= 20 q=35.0 size=    7354kB time=00:01:27.63 bitrate= 687.5kbits/
  
  frame= 1790 fps= 20 q=32.0 size=    7392kB time=00:01:28.13 bitrate= 687.1kbits/
  
  frame= 1793 fps= 20 q=32.0 size=    7402kB time=00:01:28.63 bitrate= 684.2kbits/
  
  frame= 1796 fps= 20 q=33.0 size=    7411kB time=00:01:29.09 bitrate= 681.3kbits/
  
  frame= 1796 fps= 20 q=33.0 Lsize=    7411kB time=00:01:29.09 bitrate= 681.3kbits
  
  /s speed=0.999x

  How can I debug what is wrong ?