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• Rendering YUV420P ffmpeg decoded images on QT with OpenGL, only see black screen

  17 février 2019, par Lucas Zanella

  I’ve found this QT OpenGL Widget which should render a 420PYUV image on screen. I’m feeding a ffmpeg decoded buffer into its paintGL() function but I see nothing. Neither noises or correct images, only a black screen. I’m trying to understand why.

  I want to exclude the possibilities of other things being wrong, but I need to be sure first that my code will produce anything. I std::couted some bytes from the ffmpeg just to see if they were arriving and they were. So I should see at least some noise.

  Can you see anything wrong with my code that wouldn’t make it able to render images on screen ?

  This is the widget that should output the image :

  #include "XVideoWidget.h"
  
  #include <qdebug>
  
  #include <qtimer>
  
  #include <iostream>
  
  //自动加双引号
  
  #define GET_STR(x) #x
  
  #define A_VER 3
  
  #define T_VER 4
  
  
  
  //顶点shader
  
  const char *vString = GET_STR(
  
      attribute vec4 vertexIn;
  
      attribute vec2 textureIn;
  
      varying vec2 textureOut;
  
      void main(void)
  
      {
  
          gl_Position = vertexIn;
  
          textureOut = textureIn;
  
      }
  
  );
  
  
  
  
  
  //片元shader
  
  const char *tString = GET_STR(
  
      varying vec2 textureOut;
  
      uniform sampler2D tex_y;
  
      uniform sampler2D tex_u;
  
      uniform sampler2D tex_v;
  
      void main(void)
  
      {
  
          vec3 yuv;
  
          vec3 rgb;
  
          yuv.x = texture2D(tex_y, textureOut).r;
  
          yuv.y = texture2D(tex_u, textureOut).r - 0.5;
  
          yuv.z = texture2D(tex_v, textureOut).r - 0.5;
  
          rgb = mat3(1.0, 1.0, 1.0,
  
              0.0, -0.39465, 2.03211,
  
              1.13983, -0.58060, 0.0) * yuv;
  
          gl_FragColor = vec4(rgb, 1.0);
  
      }
  
  
  
  );
  
  
  
  
  
  
  
  //准备yuv数据
  
  // ffmpeg -i v1080.mp4 -t 10 -s 240x128 -pix_fmt yuv420p  out240x128.yuv
  
  XVideoWidget::XVideoWidget(QWidget * parent)
  
  {
  
     // setWindowFlags (Qt::WindowFullscreenButtonHint);
  
    //  showFullScreen();
  
  
  
  }
  
  
  
  XVideoWidget::~XVideoWidget()
  
  {
  
  }
  
  
  
  //初始化opengl
  
  void XVideoWidget::initializeGL()
  
  {
  
      //qDebug() &lt;&lt; "initializeGL";
  
      std::cout &lt;&lt; "initializing gl" &lt;&lt; std::endl;
  
      //初始化opengl （QOpenGLFunctions继承）函数
  
      initializeOpenGLFunctions();
  
  
  
      this->m_F  = QOpenGLContext::currentContext()->functions();
  
  
  
      //program加载shader（顶点和片元）脚本
  
      //片元（像素）
  
      std::cout &lt;&lt; program.addShaderFromSourceCode(QOpenGLShader::Fragment, tString) &lt;&lt; std::endl;
  
      //顶点shader
  
      std::cout &lt;&lt; program.addShaderFromSourceCode(QOpenGLShader::Vertex, vString) &lt;&lt; std::endl;
  
  
  
      //设置顶点坐标的变量
  
      program.bindAttributeLocation("vertexIn",A_VER);
  
  
  
      //设置材质坐标
  
      program.bindAttributeLocation("textureIn",T_VER);
  
  
  
      //编译shader
  
      std::cout &lt;&lt; "program.link() = " &lt;&lt; program.link() &lt;&lt; std::endl;
  
  
  
      std::cout &lt;&lt; "program.bind() = " &lt;&lt; program.bind() &lt;&lt; std::endl;
  
  
  
      //传递顶点和材质坐标
  
      //顶点
  
      static const GLfloat ver[] = {
  
          -1.0f,-1.0f,
  
          1.0f,-1.0f,
  
          -1.0f, 1.0f,
  
          1.0f,1.0f
  
      };
  
  
  
      //材质
  
      static const GLfloat tex[] = {
  
          0.0f, 1.0f,
  
          1.0f, 1.0f,
  
          0.0f, 0.0f,
  
          1.0f, 0.0f
  
      };
  
  
  
      //顶点
  
      glVertexAttribPointer(A_VER, 2, GL_FLOAT, 0, 0, ver);
  
      glEnableVertexAttribArray(A_VER);
  
  
  
      //材质
  
      glVertexAttribPointer(T_VER, 2, GL_FLOAT, 0, 0, tex);
  
      glEnableVertexAttribArray(T_VER);
  
  
  
      //glUseProgram(&amp;program);
  
      //从shader获取材质
  
      unis[0] = program.uniformLocation("tex_y");
  
      unis[1] = program.uniformLocation("tex_u");
  
      unis[2] = program.uniformLocation("tex_v");
  
  
  
      //创建材质
  
      glGenTextures(3, texs);
  
  
  
      //Y
  
      glBindTexture(GL_TEXTURE_2D, texs[0]);
  
      //放大过滤，线性插值   GL_NEAREST(效率高，但马赛克严重)
  
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  
      //创建材质显卡空间
  
      glTexImage2D(GL_TEXTURE_2D, 0, GL_RED, width, height, 0, GL_RED, GL_UNSIGNED_BYTE, 0);
  
  
  
      //U
  
      glBindTexture(GL_TEXTURE_2D, texs[1]);
  
      //放大过滤，线性插值
  
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  
      //创建材质显卡空间
  
      glTexImage2D(GL_TEXTURE_2D, 0, GL_RED, width/2, height / 2, 0, GL_RED, GL_UNSIGNED_BYTE, 0);
  
  
  
      //V
  
      glBindTexture(GL_TEXTURE_2D, texs[2]);
  
      //放大过滤，线性插值
  
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  
      //创建材质显卡空间
  
      glTexImage2D(GL_TEXTURE_2D, 0, GL_RED, width / 2, height / 2, 0, GL_RED, GL_UNSIGNED_BYTE, 0);
  
  
  
      ///分配材质内存空间
  
      datas[0] = new unsigned char[width*height];     //Y
  
      datas[1] = new unsigned char[width*height/4];   //U
  
      datas[2] = new unsigned char[width*height/4];   //V
  
  }
  
  
  
  //刷新显示
  
  void XVideoWidget::paintGL(unsigned char**data)
  
  //void QFFmpegGLWidget::updateData(unsigned char**data)
  
  {
  
      std::cout &lt;&lt; "painting!" &lt;&lt; std::endl;
  
      memcpy(datas[0], data[0], width*height);
  
      memcpy(datas[1], data[1], width*height/4);
  
      memcpy(datas[2], data[2], width*height/4);
  
  
  
      glActiveTexture(GL_TEXTURE0);
  
      glBindTexture(GL_TEXTURE_2D, texs[0]); //0层绑定到Y材质
  
      //修改材质内容(复制内存内容)
  
      glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width, height, GL_RED, GL_UNSIGNED_BYTE, datas[0]);
  
      //与shader uni遍历关联
  
      glUniform1i(unis[0], 0);
  
  
  
  
  
      glActiveTexture(GL_TEXTURE0+1);
  
      glBindTexture(GL_TEXTURE_2D, texs[1]); //1层绑定到U材质
  
                                             //修改材质内容(复制内存内容)
  
      glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width/2, height / 2, GL_RED, GL_UNSIGNED_BYTE, datas[1]);
  
      //与shader uni遍历关联
  
      glUniform1i(unis[1],1);
  
  
  
  
  
      glActiveTexture(GL_TEXTURE0+2);
  
      glBindTexture(GL_TEXTURE_2D, texs[2]); //2层绑定到V材质
  
                                             //修改材质内容(复制内存内容)
  
      glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width / 2, height / 2, GL_RED, GL_UNSIGNED_BYTE, datas[2]);
  
      //与shader uni遍历关联
  
      glUniform1i(unis[2], 2);
  
  
  
      glDrawArrays(GL_TRIANGLE_STRIP,0,4);
  
      qDebug() &lt;&lt; "paintGL";
  
  }
  
  
  
  
  
  // 窗口尺寸变化
  
  void XVideoWidget::resizeGL(int width, int height)
  
  {
  
      m_F->glViewport(0, 0, width, height);
  
  
  
      qDebug() &lt;&lt; "resizeGL "&lt;code></iostream></qtimer></qdebug>

  Here’s a bit of code from my MainWindow :

  MainWindow::MainWindow(QWidget *parent):
  
      QMainWindow(parent)
  
      {
  
          FfmpegDecoder* ffmpegDecoder = new FfmpegDecoder();
  
          if(!ffmpegDecoder->Init()) {
  
              std::cout << "problem with ffmpeg decoder init"  << std::endl;
  
          } else {
  
              std::cout << "fmmpeg decoder initiated"  << std::endl;
  
          }
  
          XVideoWidget * xVideoWidget = new XVideoWidget(parent);
  
          ffmpegDecoder->setOpenGLWidget(xVideoWidget);
  
  
  
          mediaStream = new MediaStream(uri, ffmpegDecoder, videoConsumer);//= new MediaStream(uri, ffmpegDecoder, videoConsumer);
  
          //...
  
      }
  
      void MainWindow::run()
  
      {
  
          mediaStream->receiveFrame();
  
      }

  My main.cpp makes sure my window run() method runs in the background.

      MainWindow w;
  
      w.setFixedSize(1280,720);
  
      w.show();
  
      boost::thread mediaThread(&MainWindow::run, &w);
  
      std::cout << "mediaThread running"  << std::endl;

  If someone wants to view the entire code, please feel free to visit the commit I just did : https://github.com/lucaszanella/orwell/tree/bbd74e42bd42df685bacc5d51cacbee3a178689f

• Blog series part 2 : How to increase engagement of your website visitors, and turn them into customers

  8 septembre 2020, par Joselyn Khor — Analytics Tips, Marketing
  Long gone are the days of simply tracking page views as a measure of engagement. Now it’s about engagement analysis, which is layered and provides insight for effective data-driven decisions.

  Discover how engaged people are with your website by uncovering behavioural patterns that tell you how well your site and content is or isn’t performing. This insight helps you re-evaluate, adapt and optimise your content and strategy. The more engaged they are, the more likely you’ll be able to guide them on a predetermined journey that results in more conversions ; and helps you reach the goals you’ve set for your business. 

  Why is visitor engagement important ?

  It’s vital to measure engagement if you have anything content related that plays a role in your customer’s journey. Some websites may find more value in figuring out how engaging their entire site is, while others may only want to zone in on, say, a blogging section, e-newsletters, social media channels or sign-up pages.

  In the larger scheme of things, engagement can be seen as what’s running your site. Every aspect of the buyer’s journey requires your visitors to be engaged. Whether you’re trying to attract, convert or build a loyal audience base, you need to know your content is optimised to maintain their attention and encourage them along the path to purchase, conversion or loyalty.

  How to increase engagement with Matomo

  You need to know what’s going right or wrong to eventually be able to deliver more riveting content your visitors can’t help but be drawn to. Learn how to apply Matomo’s easy-to-use features to increase engagement :

  1. The Behaviour feature
  2. Heatmaps
  3. A/B Testing
  4. Media Analytics
  5. Transitions
  6. Custom reports
  7. Other metrics to keep an eye on

  1. Look at the Behaviour feature

  It allows you to learn how visitors are responding to your content. This information is gathered by drawing insight from features such as site search, downloads, events and content interactions. Learn more

  

  Matomo’s top five ways to increase engagement with the Behaviour feature :

  Behaviour -> Pages
  Get complete insights on what pages your users engage with, what pages provide little value to your business and see the results of entry and exit pages. If important content is generating low traffic, you need to place it where it can be seen. Spend time where it matters and focus on the content that will engage with your users and see how it eventually converts them into customers.

  Behaviour -> Site search
  Site search tracks how people use your website’s internal search engine. You can see :

  • What search keywords visitors used on your website’s internal search.
  • Which of those keywords resulted in no results (what content your visitors are looking for but cannot find).
  • What pages visitors visited immediately after a search.
  • What search categories visitors use (if your website employs search categories).

  Behaviour -> Downloads
  What are users wanting to take away with them ? They could be downloading .pdfs, .zip files, ebooks, infographics or other free/paid resources. For example, if you were working for an education institution and created valuable information packs for students that you made available online in .pdf format. To see an increase in downloads meant students were finding the .pdfs and realising the need to download them. No downloads could mean the information packs weren’t being found which would be problematic.

  Behaviour -> Events
  Tracking events is a very useful way to measure the interactions your users have with your website content, which are not directly page views or downloads.

  How have Events been used effectively ? A great example comes from one of our customers, Catalyst. They wanted to capture and measure the user interaction of accordions (an area of content that expands or closes depending on how a user interacts with it) to see if people were actually getting all the information available to them on this one page. By creating an Event to record which accordion had been opened, as well as creating events for other user interactions, they were able to figure out which content got the most engagement and which got the least. Being able to see how visitors navigated through their website helped them optimise the site to ensure people were getting the relevant information they were craving.

  Behaviour -> Content interactions
  Content tracking allows you to track interaction within the content of your web page. Go beyond page views, bounce rates and average time spent on page with your content. Instead, you can analyse content interaction rates based on mouse clicking and configuring scrolling or hovering behaviours to see precisely how engaged your users are. If interaction rates are low, perhaps you need to restructure your page layout to grab your user’s attention sooner. Possibly you will get more interaction when you have more images or banner ads to other areas of your business.

  

  Watch this video to learn about the Behaviour feature

  2. Set up Heatmaps

  Effortlessly discover how your visitors truly engage with your most important web pages that impact the success of your business. Heatmaps shows you visually where your visitors try to click, move the mouse and how far down they scroll on each page.

  

  You don’t need to waste time digging for key metrics or worry about putting together tables of data to understand how your visitors are interacting with your website. Heatmaps make it easy and fast to discover where your users are paying their attention, where they have problems, where useless content is and how engaging your content is. Get insights that you cannot get from traditional reports. Learn more

  TRY IT FOR FREE

  3. Carry out A/B testing

  With A/B Testing you reduce risk in your decision-making and can test what your visitors are responding well to. 

  

  Ever had discussions with colleagues about where to place content on a landing page ? Or discussed what the call-to-action should be and assumed you were making the best decisions ? The truth is, you never know what really works the best (and what doesn’t) unless you test it. Learn more

  How to increase engagement with A/B Testing : Test, test and test. This is a surefire way to learn what content is leading your visitors on a path to conversion and what isn’t.

  4. Media Analytics

  Tells you how visitors are engaging with your video or audio content, and whether they’re leading to your desired conversions. Track :

  • How many plays your media gets and which parts they viewed
  • Finish rates
  • How your media was consumed over time
  • How media was consumed on specific days
  • Which locations your users were viewing your content from
  • Learn more

  

  How to increase engagement with Media Analytics : These metrics give a picture of how audiences are behaving when it comes to your content. By showing insights such as, how popular your media content is, how engaging it is and which days content will be most viewed, you can tailor content strategies to produce content people will actually find interesting and watch/listen.

  Matomo example : When we went through the feature video metrics on our own site to see how our videos were performing, we noticed our Acquisition video had a 95% completion rate. Even though it was longer than most videos, the stats showed us it had, by far, the most engagement. By using Media Analytics to get insights on the best and worst performing videos, we gathered useful info to help us better allocate resources effectively so that in the future, we’re producing more videos that will be watched.

  5. Investigate transitions

  See which page visitors are entering the site from and where they exit to. Transitions shows engagement on each page and whether the content is leading them to the pages you want them to be directed to.

  

  This gives you a greater understanding of user pathways. You may be assuming visitors are finding your content from one particular pathway, but figure out users are actually coming through other channels you never thought of. Through Transitions, you may discover and capitalise on new opportunities from external sites.

  How to increase engagement with Transitions : Identify clearly where users may be getting distracted to click away and where other pages are creating opportunity to click-through to conversion. 

  6. Create Custom Reports

  You can choose from over 200 dimensions and metrics to get the insights you need as well as various visualisation options. This makes understanding the data incredibly easy and you can get the insights you need instantly for faster results without the need for a developer. Learn more

  

  How to increase engagement with Custom Reports : Set custom reports to see when content is being viewed and figure out how engaged users are by looking at different hours of the day or which days of the week they’re visiting your website. For example, you could be wondering what hour of the day performed best for converting your customers. Understanding these metrics helps you figure out the best time to schedule your blog posts, pay-per-click advertising, edms or social media posts knowing that your visitors are more likely to convert at different times.

  TRY IT FOR FREE

  7. Other metrics to key an eye on …

  A good indication of a great experience and of engagement is whether your readers, viewers or listeners want to do it again and again.

  “Best” metrics are hard to determine so you’ll need to ask yourself what you want to do or what you want your site to do. How do you want your users to behave or what kind of buyer’s journey do you want them to have ?

  Want to know where to start ? Look at …

  • Bounce rate – a high bounce rate isn’t great as people aren’t finding what they’re looking for and are leaving without taking action. (This offers great opportunities as you can test to see why people are bouncing off your site and figure out what you need to change.)
  • Time on site – a long time on site is usually a good indication that people are spending time reading, navigating and being engaged with your website. 
  • Frequency of visit – how often do people come back to interact with the content on your website ? The higher the % of your visitors that come back time and time again will show how engaged they are with your content.
  • Session length/average session duration – how much time users spend on site each session
  • Pages per session – is great to show engagement because it shows visitors are happy going through your website and learn more about your business.

  Key takeaway

  Whichever stage of the buyer’s journey your visitors are in, you need to ensure your content is optimised for engagement so that visitors can easily spend time on your website.

  “Every single visit by every single visitor is no longer judged as a success or a failure at the end of 29 min (max) session in your analytics tool. Every visit is not a ‘last-visit’, rather it becomes a continuous experience leading to a win-win outcome.” – Avinash Kaushik

  As you can tell, one size does not fit all when it comes to analysing and measuring engagement, but with a toolkit of features, you can make sure you have everything you need to experiment and figure out the metrics that matter to the success of your business and website.

  Concurrently, these gentle nudges for visitors to consume more and more content encourages them along their path to purchase, conversion or loyalty. They get a more engaging website experience over time and you get happy visitors/customers who end up coming back for more.

  TRY IT FOR FREE

  Want to learn how to increase conversions with Matomo ? Look out for the final in this series : part 3 ! We’ll go through how you can boost conversions and meet your business goals with web analytics. 

• How to write UI tests for your plugin – Introducing the Piwik Platform

  18 février 2015, par Thomas Steur — Development

  This is the next post of our blog series where we introduce the capabilities of the Piwik platform (our previous post was How to write unit tests for your plugin). This time you’ll learn how to write UI tests in Piwik. For this tutorial you will need to have basic knowledge of JavaScript and the Piwik platform.

  What is a UI test ?

  Some might know a UI test under the term ‘CSS test’ or ‘screenshot test’. When we speak of UI tests we mean automated tests that capture a screenshot of a URL and then compare the result with an expected image. If the images are not exactly the same the test will fail. For more information read our blog post about UI Testing.

  What is a UI test good for ?

  We use them to test our PHP Controllers, Twig templates, CSS, and indirectly test our JavaScript. We do usually not write Unit or Integration tests for our controllers. For example we use UI tests to ensure that the installation, the login and the update process works as expected. We also have tests for most pages, reports, settings, etc. This increases the quality of our product and saves us a lot of time as it is easy to write and maintain such tests. All UI tests are executed on Travis after each commit and compared with our expected screenshots.

  Getting started

  In this post, we assume that you have already installed Piwik 2.11.0 or later via git, set up your development environment and created a plugin. If not, visit the Piwik Developer Zone where you’ll find the tutorial Setting up Piwik and other Guides that help you to develop a plugin.

  Next you need to install the needed packages to execute UI tests.

  Let’s create a UI test

  We start by using the Piwik Console to create a new UI test :

  ./console generate:test --testtype ui

  The command will ask you to enter the name of the plugin the created test should belong to. I will use the plugin name “Widgetize”. Next it will ask you for the name of the test. Here you usually enter the name of the page or report you want to test. I will use the name “WidgetizePage” in this example. There should now be a file plugins/Widgetize/tests/UI/WidgetizePage_spec.js which contains already an example to get you started easily :

  describe("WidgetizePage", function () {
  
      var generalParams = 'idSite=1&period=day&date=2010-01-03';
  
  
  
      it('should load a simple page by its module and action', function (done) {
  
          var screenshotName = 'simplePage';
  
          // will save image in "processed-ui-screenshots/WidgetizePageTest_simplePage.png"
  
  
  
          expect.screenshot(screenshotName).to.be.capture(function (page) {
  
              var urlToTest = "?" + generalParams + "&module=Widgetize&action=index";
  
              page.load(urlToTest);
  
          }, done);
  
      });
  
  });

  What is happening here ?

  This example declares a new set of specs by calling the method describe(name, callback) and within that a new spec by calling the method it(description, func). Within the spec we load a URL and once loaded capture a screenshot of the whole page. The captured screenshot will be saved under the defined screenshotName. You might have noticed we write our UI tests in BDD style.

  Capturing only a part of the page

  It is good practice to not always capture the full page. For example many pages contain a menu and if you change that menu, all your screenshot tests would fail. To avoid this you would instead have a separate test for your menu. To capture only a part of the page simply specify a jQuery selector and call the method captureSelector instead of capture :

  var contentSelector = '#selector1, .selector2 .selector3';
  
  // Only the content of both selectors will be in visible in the captured screenshot
  
  expect.screenshot('page_partial').to.be.captureSelector(contentSelector, function (page) {
  
      page.load(urlToTest);
  
  }, done);

  Hiding content

  There is a known issue with sparklines that can fail tests randomly. Also version numbers or a date that changes from time to time can fail tests without actually having an error. To avoid this you can prevent elements from being visible in the captured screenshot via CSS as we add a CSS class called uiTest to the HTML element while tests are running.

  .uiTest .version { visibility:hidden }

  Running a test

  To run the previously generated tests we will use the command tests:run-ui :

  ./console tests:run-ui WidgetizePage

  After running the tests for the first time you will notice a new folder plugins/PLUGINNAME/tests/UI/processed-ui-screenshots in your plugin. If everything worked, there will be an image for every captured screenshot. If you’re happy with the result it is time to copy the file over to the expected-ui-screenshots folder, otherwise you have to adjust your test until you get the result you want. From now on, the newly captured screenshots will be compared with the expected images whenever you execute the tests.

  Fixing a test

  At some point your UI test will fail, for example due to expected CSS changes. To fix a test all you have to do is to copy the captured screenshot from the folder processed-ui-screenshots to the folder expected-ui-screenshots.

  Executing the UI tests on Travis

  In case you have not generated a .travis.yml file for your plugin yet you can do this by executing the following command :

  ./console generate:travis-yml --plugin PLUGINNAME

  Next you have to activate Travis for your repository.

  Advanced features

  Isn’t it easy to create a UI test ? We never even created a file ! Of course you can accomplish even more if you want. For example you can specify a fixture to be inserted before running the tests which is useful when your plugin requires custom data. You can also control the browser as it was a human by clicking, moving the mouse, typing text, etc. If you want to discover more features have a look at our existing test cases.

  If you have any feedback regarding our APIs or our guides in the Developer Zone feel free to send it to us.