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• select a screen section ffmpeg c++ on macos

  21 avril 2022, par C1ngh10

  I am trying to record the screen on macos, with ffmpeg. I would like to be able to select a section of the screen instead of the whole desktop. I tried to set several options such as vf, with values like "crop=150:150:0:0", or video_size with value "150x150". The result was that the output video had the correct dimensions (150x150) but whole screen has been recorded instead of the specified section. Does anybody know another way to do that ?

  


  int ScreenRecorder::openVideoDevice() {
    value = 0;
    videoOptions = nullptr;
    pAVFormatContext = nullptr;

    pAVFormatContext = avformat_alloc_context();


    string dimension = to_string(width) + "x" + to_string(height);
    av_dict_set(&videoOptions, "video_size", dimension.c_str(), 0);   //option to set the dimension of the screen section to record
    value = av_dict_set(&videoOptions, "framerate", "25", 0);
    if (value < 0) {
        cerr << "Error in setting dictionary value (setting framerate)" << endl;
        exit(-1);
    }

    value = av_dict_set(&videoOptions, "preset", "ultrafast", 0);
    if (value < 0) {
        cerr << "Error in setting dictionary value (setting preset value)" << endl;
        exit(-1);
    }

    //The distance from the left edge of the screen or desktop
    value = av_dict_set(&videoOptions, "vf", ("crop=" + to_string(width) + ":" + to_string(height) + ":" + to_string(x_offset) + ":" +
        to_string(y_offset)).c_str(), 0);

    if (value < 0) {
        cerr << "Error in setting crop" << endl;
        exit(-1);
    }

    value = av_dict_set(&videoOptions, "pixel_format", "yuv420p", 0);
    if (value < 0) {
        cerr << "Error in setting pixel format" << endl;
        exit(-1);
    }
    
    pAVInputFormat = av_find_input_format("avfoundation");

    if (avformat_open_input(&pAVFormatContext, "1:none", pAVInputFormat, &videoOptions) != 0) {
        cerr << "Error in opening input device" << endl;
        exit(-1);
    }
    //get video stream infos from context
    value = avformat_find_stream_info(pAVFormatContext, nullptr);
    if (value < 0) {
        cerr << "Error in retrieving the stream info" << endl;
        exit(-1);
    }

    VideoStreamIndx = -1;
    for (int i = 0; i < pAVFormatContext->nb_streams; i++) {
        if (pAVFormatContext->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
            VideoStreamIndx = i;
            break;
        }
    }
    if (VideoStreamIndx == -1) {
        cerr << "Error: unable to find video stream index" << endl;
        exit(-2);
    }

    pAVCodecContext = pAVFormatContext->streams[VideoStreamIndx]->codec;
    pAVCodec = avcodec_find_decoder(pAVCodecContext->codec_id/*params->codec_id*/);
    if (pAVCodec == nullptr) {
        cerr << "Error: unable to find decoder video" << endl;
        exit(-1);
    }

    return 0;
}


  


• How to stream live h.264 (IP camera) video to browser ? (bonus : low bandwidth and latency)

  4 octobre 2018, par Ryan Griggs

  I need to stream live h.264-encoded video from an IP camera to the browser, while supporting all common browsers and mobile devices (i.e. Android, Firefox, Chrome, IE, Safari (Mac OS and iOS)), and while keeping bandwidth requirements and latency to a minimum.

  MPEG-DASH requires browser support for Media Source Extensions, which are NOT supported by iOS. So that’s out.

  HLS is only supported by Safari and Edge.

  Also DASH seems to impose a latency of several seconds, which is not preferable.

  I would like to be able to chunk the incoming h.264 data (i.e. fragmented MP4), pass the chunked data to the browser via Websockets, then dump the chunks into some sort of player as they arrive.

  Broadway and its forks are a javascript h.264 decoder, and there is a Broadway-stream project that supports streams instead of files, but the docs are poor and I can only find examples of streaming when the source is not live.

  The most pressing question is : how do I hand the "chunked data" to a player or Video HTML element as it arrives at the browser ?

  I think the ideal setup would be to

  1. Use ffmpeg to transcode the original video to a chunked format (fMP4)
  2. Pipe the chunked output to a Node JS app which emits each chunk out through a Websocket to all connected viewers
  3. Viewers’ browsers dump each incoming chunk into some sort of decoder which renders the video.

  I’m clear up to the point of handing the received chunks to a video decoder. How can that be done without depending on Media Source Extensions, and allowing viewers to join the stream at random times ?

• Matomo to end support for Internet Explorer 11

  21 septembre 2021, par Matomo Core Team — Community

  A lot of the Matomo user interface is built on top of a programming framework called “Angular.js”. The support for this framework will end very soon, meaning we have to migrate the Matomo user interface to an alternative framework. The Matomo development team has chosen this new framework to be “Vue.js 3”.

  Unfortunately, Vue.js does not support Internet Explorer 11 (IE 11). Therefore, we have to drop the support for IE 11. Many other popular services like Microsoft and WordPress recently did the same. This is happening because IE 11 was released about 8 years ago and is now used by less than 0.5% of the internet. 

  When will this change happen ?

  Our next release (Matomo 4.5) will still support IE 11. It will show a notification in the user interface if you are using Internet Explorer to make you aware of this upcoming change. 

  When Matomo 4.6 is released around November 2021, then IE 11 will no longer be supported.

  What does “end support” mean ?

  The Matomo user interface will work less and less over time for people using IE 11 as a browser. While Matomo 4.6 might still mostly work with IE 11, once we migrate more of the user interface the functionality will stop working completely. It’s possible that even Matomo 4.6 will no longer be functional with IE 11 at all.

  What should I do now ?

  If you are impacted by this, then we strongly recommend that you switch to a more modern browser. Preferably a privacy-friendly browser like Mozilla Firefox or Brave. But any modern browser including Microsoft Edge, Safari and Google Chrome will work just fine.

  If you can’t use a different browser and you are using Matomo On-Premise, then you can install and configure this new plugin which lets you only receive Matomo core updates that are compatible with IE 11. This will prevent you from accidentally upgrading to a Matomo core release that doesn’t work with IE 11, and you can still receive critical security updates and bug fixes until February 2022.

  Will this affect the Matomo JavaScript tracker ?

  No, all visitors using IE 11 will still be tracked and Matomo tracker will support the same browsers as before. Meaning also some older versions of Internet Explorer are still supported.

  Have any questions about this ?

  Get in touch with us