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• Supporting HEVC/H.265 videos in Electron

  1 March 2021, by Elmo

  Chrome/Electron don't normally support H.265 videos. I want the user to be able to play .mov files recorded by Apple devices in my app. How can I do this?

  


  Possible approaches:

  


  

  1. Use ffmpeg to transcode to H.264 in real-time, which will be resource intensive (not ideal)

  


  2. Use WebAssembly to render the video in a <canvas></canvas> tag (not ideal)

  


  3. Fork and manually add H.265 codec support to Chrome/Electron (overkill)

  


  4. Use a native module that renders the video in a <canvas></canvas> or BrowserView

  


  


• Live Streaming WebM with Wowza Server

  2 December 2010, by noreply@blogger.com (John Luther)

  Guest blogger Charlie Good is CTO and co-founder of Wowza Media Systems

  As a company, we at Wowza move fast and like to tinker. When WebM was announced in May, we saw it as a promising new approach to HTML5 video and decided to do an experiment with live WebM streaming over http.

  Adding WebM VP8 video and Vorbis audio to the other encoding formats that our server supported was easy (we designed the Wowza server to be codec-agnostic). We then created a WebMfile and implemented WebM HTTP streaming.

  We originally created the demo as a proof-of-concept for the IBC show in September, 2010 but have made it available to watch on our web site.

  The file is streamed live (more precisely, "pseudo-live") over http using the Wowza server-side publishing API (PDF). The result is very impressive; playback starts fast and the VP8 image quality is fantastic.

  You will need a WebM-enabled browser or VLC media player 1.1.5 to view the live stream.

  If you’re interested in keeping up with Wowza’s WebM progress, visit Wowza Labs or drop us a note at info@wowzamedia.com.

  

• How to create video using avcodec from jpeg images of type OpenCV::Mat?

  23 July 2015, by theateist

  I have colored jpeg images of OpenCV::Mat type and I create from them video using avcodec. The video that I get is upside-down, black & white and each row of each frame is shifted and I got diagonal line. What could be the reason for such output?
  Follow this link to watch the video I get using avcodec.
  I’m using acpicture_fill function to create avFrame from cv::Mat frame!

  P.S.
  Each cv::Mat cvFrame has width=810, height=610, step=2432
  I noticed that avFrame (that is filled by acpicture_fill) has linesize[0]=2430
  I tried manually setting avFrame->linesizep0]=2432 and not 2430 but it still didn’t helped.

  ======== CODE =========================================================

  AVCodec *encoder = avcodec_find_encoder(AV_CODEC_ID_H264);
  
  AVStream *outStream = avformat_new_stream(outContainer, encoder);
  
  avcodec_get_context_defaults3(outStream->codec, encoder);
  
  
  
  outStream->codec->pix_fmt = AV_PIX_FMT_YUV420P;
  
  outStream->codec->width = 810;
  
  outStream->codec->height = 610;
  
  //...
  
  
  
  SwsContext *swsCtx = sws_getContext(outStream->codec->width, outStream->codec->height, PIX_FMT_RGB24,
  
                                      outStream->codec->width, outStream->codec->height,  outStream->codec->pix_fmt, SWS_BICUBIC, NULL, NULL, NULL);
  
  
  
  for (uint i=0; i < frameNums; i++)
  
  {
  
      // get frame at location I using OpenCV
  
      cv::Mat cvFrame;
  
      myReader.getFrame(cvFrame, i); 
  
      cv::Size frameSize = cvFrame.size();    
  
      //Each cv::Mat cvFrame has  width=810, height=610, step=2432
  
  
  
  
  
  1.  // create AVPicture from cv::Mat frame
  
  2.  avpicture_fill((AVPicture*)avFrame, cvFrame.data, PIX_FMT_RGB24, outStream->codec->width, outStream->codec->height);
  
  3avFrame->width = frameSize.width;
  
  4.  avFrame->height = frameSize.height;
  
  
  
      // rescale to outStream format
  
      sws_scale(swsCtx, avFrame->data, avFrame->linesize, 0, outStream->codec->height, avFrameRescaledFrame->data, avFrameRescaledFrame ->linesize);
  
  encoderRescaledFrame->pts=i;
  
  avFrameRescaledFrame->width = frameSize.width;
  
      avFrameRescaledFrame->height = frameSize.height;
  
  
  
  av_init_packet(&avEncodedPacket);
  
      avEncodedPacket.data = NULL;
  
      avEncodedPacket.size = 0;
  
  
  
      // encode rescaled frame
  
      if(avcodec_encode_video2(outStream->codec, &avEncodedPacket, avFrameRescaledFrame, &got_frame) < 0) exit(1);
  
      if(got_frame)
  
      {
  
          if (avEncodedPacket.pts != AV_NOPTS_VALUE)
  
              avEncodedPacket.pts =  av_rescale_q(avEncodedPacket.pts, outStream->codec->time_base, outStream->time_base);
  
          if (avEncodedPacket.dts != AV_NOPTS_VALUE)
  
              avEncodedPacket.dts = av_rescale_q(avEncodedPacket.dts, outStream->codec->time_base, outStream->time_base);
  
  
  
          // outContainer is "mp4"
  
          av_write_frame(outContainer, & avEncodedPacket);
  
  
  
          av_free_packet(&encodedPacket);
  
      }
  
  }

  UPDATED

  As @Alex suggested I changed the lines 1-4 with the code below

  int width = frameSize.width, height = frameSize.height; 
  
  avpicture_alloc((AVPicture*)avFrame, AV_PIX_FMT_RGB24, outStream->codec->width, outStream->codec->height);
  
  for (int h = 0; h < height; h++)
  
  {
  
       memcpy(&(avFrame->data[0][h*avFrame->linesize[0]]), &(cvFrame.data[h*cvFrame.step]), width*3);
  
  }

  The video (here) I get now is almost perfect. It’s NOT upside-down, NOT black & white, BUT it seems that one of the RGB components is missing. Every brown/red colors became blue (in original images it should be vice-verse).
  What could be the problem? Could rescaling(sws_scale) to AV_PIX_FMT_YUV420P format causes this?