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• We are hiring engineers to build an awesome product and platform used by millions of people

  16 février 2016, par Piwik Core Team — Uncategorized

  Are you ready for a new challenge ? Or maybe you know someone who is looking for a change ? We have some exciting problems to solve and are looking for senior developers to work with us and our community on our open source Piwik Analytics platform. Piwik is used by more than one million websites all over the world. It is deployed on more than 300.000 servers and some users track more than 1 billion actions per month.

  What is it like to work on Piwik ?

  We develop this software using modern PHP, MySQL, Redis, AngularJS and more. We provide several kind of APIs and a plugin architecture to allow developers to extend and change Piwik to their needs. However, we would not be Piwik if we stopped at this point ! We want to turn Piwik into an even more awesome product and platform.
  You can imagine there is a lot to do and many challenges to face !

  While one part is to always make Piwik scale better and to improve UI and UX, we also want to provide simple APIs to make the life of developers as pleasant as possible. We aim to solve things the right way and our thousands of unit, integration, system, JavaScript and screenshot tests help us to innovate and to not be afraid of change. We like clean code and constant improvements.

  The Piwik team lives in New Zealand and Europe (Germany). We do the vast majority of our collaboration online. Our values include being open, transparent and sharing knowledge. For this we use tools like GitHub and Slack to communicate and Quake servers to take our minds off complex challenges. We are a small, flexible team, so when you come aboard, you will play an integral part in engineering and have a big impact on the product loved by so many people. You’ll help to create a welcoming environment for new contributors and set an example with your development practices and communications skills.

  Apply now, or spread the word !

  If you have strong skills in PHP send us an email with your CV and tell us a little about yourself and your experience in engineering complex applications.

  Apply for a job here http://piwik.org/jobs/ and if you’re maybe not the right candidate, contribute to the project by sharing this blog post and by sending it to your friends !

• We are hiring engineers to build an awesome product and platform used by millions of people

  16 février 2016, par Piwik Core Team — Jobs

  Are you ready for a new challenge ? Or maybe you know someone who is looking for a change ? We have some exciting problems to solve and are looking for senior developers to work with us and our community on our open source Piwik Analytics platform. Piwik is used by more than one million websites all over the world. It is deployed on more than 300.000 servers and some users track more than 1 billion actions per month.

  What is it like to work on Piwik ?

  We develop this software using modern PHP, MySQL, Redis, AngularJS and more. We provide several kind of APIs and a plugin architecture to allow developers to extend and change Piwik to their needs. However, we would not be Piwik if we stopped at this point ! We want to turn Piwik into an even more awesome product and platform.
  You can imagine there is a lot to do and many challenges to face !

  While one part is to always make Piwik scale better and to improve UI and UX, we also want to provide simple APIs to make the life of developers as pleasant as possible. We aim to solve things the right way and our thousands of unit, integration, system, JavaScript and screenshot tests help us to innovate and to not be afraid of change. We like clean code and constant improvements.

  The Piwik team lives in New Zealand, Europe (Poland, Germany) and in the U.S. We do the vast majority of our collaboration online. Our values include being open, transparent and sharing knowledge. For this we use tools like GitHub and Slack to communicate and Quake servers to take our minds off complex challenges. We are a small, flexible team, so when you come aboard, you will play an integral part in engineering and have a big impact on the product loved by so many people. You’ll help to create a welcoming environment for new contributors and set an example with your development practices and communications skills.

  Apply now, or spread the word !

  If you have strong skills in PHP send us an email with your CV and tell us a little about yourself and your experience in engineering complex applications.

  Apply for a job here http://piwik.org/jobs/ and if you’re maybe not the right candidate, contribute to the project by sharing this blog post and by sending it to your friends !

• How would I assign multiple MMAP's from single file descriptor ?

  9 juin 2011, par Alex Stevens

  So, for my final year project, I'm using Video4Linux2 to pull YUV420 images from a camera, parse them through to x264 (which uses these images natively), and then send the encoded stream via Live555 to an RTP/RTCP compliant video player on a client over a wireless network. All of this I'm trying to do in real-time, so there'll be a control algorithm, but that's not the scope of this question. All of this - except Live555 - is being written in C. Currently, I'm near the end of encoding the video, but want to improve performance.

  To say the least, I've hit a snag... I'm trying to avoid User Space Pointers for V4L2 and use mmap(). I'm encoding video, but since it's YUV420, I've been malloc'ing new memory to hold the Y', U and V planes in three different variables for x264 to read upon. I would like to keep these variables as pointers to an mmap'ed piece of memory.

  However, the V4L2 device has one single file descriptor for the buffered stream, and I need to split the stream into three mmap'ed variables adhering to the YUV420 standard, like so...

  buffers[n_buffers].y_plane = mmap(NULL, (2 * width * height) / 3,
  
                                      PROT_READ | PROT_WRITE, MAP_SHARED,
  
                                      fd, buf.m.offset);
  
  buffers[n_buffers].u_plane = mmap(NULL, width * height / 6,
  
                                      PROT_READ | PROT_WRITE, MAP_SHARED,
  
                                      fd, buf.m.offset +
  
                                      ((2 * width * height) / 3 + 1) /
  
                                      sysconf(_SC_PAGE_SIZE));
  
  buffers[n_buffers].v_plane = mmap(NULL, width * height / 6,
  
                                      PROT_READ | PROT_WRITE, MAP_SHARED,
  
                                      fd, buf.m.offset +
  
                                      ((2 * width * height) / 3 + 
  
                                      width * height / 6 + 1) / 
  
                                      sysconf(_SC_PAGE_SIZE));

  Where "width" and "height" is the resolution of the video (eg. 640x480).

  From what I understand... MMAP seeks through a file, kind of like this (pseudoish-code) :

  fd = v4l2_open(...);
  
  lseek(fd, buf.m.offset + (2 * width * height) / 3);
  
  read(fd, buffers[n_buffers].u_plane, width * height / 6);

  My code is located in a Launchpad Repo here (for more background) :
  http://bazaar.launchpad.net/ alex-stevens/+junk/spyPanda/files (Revision 11)

  And the YUV420 format can be seen clearly from this Wiki illustration : http://en.wikipedia.org/wiki/File:Yuv420.svg (I essentially want to split up the Y, U, and V bytes into each mmap'ed memory)

  Anyone care to explain a way to mmap three variables to memory from the one file descriptor, or why I went wrong ? Or even hint at a better idea to parse the YUV420 buffer to x264 ? :P

  Cheers ! ^^