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• Streaming android to windows

  13 juin 2017, par iYehuda

  I’m writing an app that enables controlling android devices from windows machines.
  Major part of controlling the device is viewing it’s screen. Currently, my android app (Java code) captures the screen on a fixed rate, compresses it (JPEG) and sends it, while the windows side (C# code) receives buffers of data, each for frame, decompresses them and displays the last decompressed frame.

  Two issues came up from this solution :

  1. Compression of a single image takes 0.3 seconds, which limits me to low FPS streaming with single thread for compressing. I made a thread pool for compressing captured frames, and it damages the app performance.

  2. The compression is not optimal. The screen can be idle for a while and a continuous transmission of the same frame would be done. Usage of streaming/encoding format would be handful and can ease the network traffic.

  I searched for encoding APIs such as MediaCodec and third party libraries such as ffmpeg. All those libraries encode videos and write them to files (maybe I misunderstood them ?).

  What API can I use for streaming my screen and follow these requirements :

  • Fast encoding / non blocking API
  • Outputs raw binary data for each frame. The data must be sent immediately
  • Can be embedded into my existing applicative protocol (protocol buffers based)
  • Available on C# (Windows) and Java or C++ (Android)

• Still on Piwik 2 ? Update now to Piwik 3, the most efficient and secure Piwik version

  5 avril 2017, par Piwik Core Team — Community

  It has been almost four months since we released Piwik 3. The major new release came with a new UI, performance and security improvements. If you are still on Piwik 2, the security improvements alone should be worth updating your Piwik now to Piwik 3. We cannot recommend this enough.

  Since the Piwik 3.0 release we have released three new versions that fix over 250 issues including more performance and security issues. And new features : the Life Time Revenue, or the Cross Domain linking feature to track visitors across different domains accurately. Also, most plugins from the Piwik Marketplace are now compatible with Piwik 3 so there is no reason to wait anymore.

  The update to Piwik 3 should be smooth, but may take a while depending on the amount of data you have. If you have any problem with the update, feel free to get in touch with us. At Piwik and at InnoCraft, the company of the makers of Piwik, we have successfully updated many Piwik installations.

  

  Wondering what’s changed ?

  • Piwik 3.0.0 Changelog
  • Piwik 3.0.1 Changelog
  • Piwik 3.0.2 Changelog
  • Piwik 3.0.3 Changelog
  • Piwik 3.0.4 Changelog

• OpenCV no longer opens video files VideoCapture

  15 février 2018, par gruffmeister

  I have a problem seemingly caused by OpenCV 3.xx - the problem does not manifest in OpenCV 2.xx

  The issue is reading video files. I’ve set my code up as follows :

  >#include 
  
  >#include 
  
  >#include 
  
  >#include 
  
  >#include 
  
  
  
  >int main()
  
  
  
  >    cv::VideoCapture cap;
  
  >    cv::Mat frame;
  
  >    if(!cap.open("Myfile.avi"))
  
  >        std::cout << "Open failed" << std::endl;
  
  >    else
  
  >        cap.read(frame);
  
  >
  
  >    cv::imshow("Frame", frame);
  
  >    cv::waitKey(5000);
  
  >    return 0;

  Now the problem is when the code gets to "cap.read(frame)" I get a "vector subscript is out of range" error with OpenCV 3.40 and this does not happen with my build of OpenCV 2.4.9. The format of the file is in avi, its not some weird codec, and clearly it works in previous versions of OpenCV.

  I’ve tried other OpenCV 3.xx builds and I get the same or similar problems with simply reading a file in.

  My question is twofold :
  How do I get OpenCV 3.xx to work with reading video files (or do I need to regress to 2.xx ?)

  Why has the major revision change completely screwed up video file reading ? That doesn’t make any sense for a computer vision API.

  As a guess it will be something to do with the FFMPEG implementation because various searches have turned up other people having issues with this.

  Any help is much appreciated.

  Thanks