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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. 

• Death of A Micro Center

  21 septembre 2012, par Multimedia Mike — History

  The Micro Center computer store located in Santa Clara, CA, USA closed recently :

  
  
  

  I liked Micro Center. I have liked Micro Center ever since I first visited their Denver, CO location 10 years ago. I would sometimes drive an hour in each direction just to visit that shop. I was excited to see that they had a location in the Bay Area when I moved here a few years ago (despite the preponderance of Fry’s stores).

  Now this location is gone. I wonder how much of the “we couldn’t come to favorable terms on a lease” was true (vs. an excuse to close a retail store at a time when more business is moving online, particularly in the heart of Silicon Valley). But that’s not what I wanted to discuss. I came here to discuss…

  The Micro Center Window Logos

  The craziest part about shopping the Santa Clara Micro Center location was the logos they displayed on the window outside. Every time I saw it, it made me sentimental for a time when some of these logos were current, or when some of these companies were still in business. Some of the logos on their front window were for companies I’ve never heard of. It reminds me of the nearby 7-11 convenience stores when I was growing up– their walls were decorated with people sporting embarrassingly 1970s styles long after the 1970s had transpired.

  I thought I would record what those front window logos were and try to pinpoint when the store launched exactly (assuming the logos have been their since the initial opening and never changed).

  
  
  Click for larger image
  

  Here we have Lotus, Hewlett Packard/HP, Corel, Fuji, Power Macintosh, NEC, and Fujitsu. Lotus was purchased by IBM in 1995 and still seems to be maintained as a separate brand. The Power Macintosh was introduced as a brand in 1994. Corel’s logo has seen a few mutations over the years but I don’t know when this one fell out of favor.

  Fuji (vs. Fujitsu) appears to refer to Fujifilm, though this logo is also obsolete.

  
  
  Click for larger image
  

  Hayes– I specifically remember reading the Slashdot post accouncing that Hayes is dead (followed by many comments reminiscing about the Hayes command set). Here is the post, from early 1999.

  From Googling, it doesn’t appear IBM still has a presence in the consumer computing space (though they do have something pertaining to software for consumer products). Then there’s the good old rainbow Apple logo, something that went away in 1997. I suspect 1997 was also the last hurrah of the name ‘Macintosh’ (though I remember mistakenly referring to Apple computer products as Macintoshes well into the mid-2000s and inadvertently angering some Apple enthusiasts).

  
  
  Click for larger image
  

  As for the next segment, obviously, both Sony and Toshiba are still very much alive. Iomega was acquired by EMC in 2008 but is still maintained as a separate brand. USRobotics is still around and making — what else ? — 56K modems (and their current logo is slightly different than the one seen here).

  Targus seems to be a case maker (“Leading Provider of Cases, Bags and Accessories for Laptops and Tablets”). I wonder if that’s just their current business or if they had more areas long ago ? It seems strange that they would get brand billing like this.

  Finally, searching for information about Practical Peripherals only produces sites about how they’re long dead (like this history lesson). It’s unclear when they died.

  The interior of this store was also decorated with more technology company logos near the ceiling (I didn’t really register that fact until I had visited many times). Regrettably, I now won’t be able to see how up to date those logos were.

  Based on the data points above, it’s safe to conclude that the store opened between 1995 or 1996 (again, assuming the logos were placed at opening and never changed).

  Epilogue

  Here’s one more curious item still visible from the outside :

  
  
  

  “See the world’s fastest PC !” Featuring an Intel Core 2 Extreme ? That CPU dates back to 2007 and was succeeded by Nehalem in late 2008. So even that sign, which is presumably easier and cleaner to replace than the window logos, was absurdly out of date.