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• Simulating MPEG1/2 transmission over a noisy channel [on hold]

  17 novembre 2015, par StepTNT

  The question may sound out of scope here but this is my last resource.

  I need to write a software that does :

  1. Get an uncompressed video from disk
  2. Compress it into MPEG-1 or MPEG-2 being able to change quantization matrix, GOP size and/or macroblock size for DCT/motion search
  3. Apply a repetition code to add redundancy
  4. Simulate transmission over a noisy channel with given error rate
  5. Reconstruct the original stream from the repetition code
  6. Decode the video and compare it with the original one by gathering stats like frame-by-frame difference, file size and stuff like that

  This should by done by a nice GUI to show the input and output videos, alongside their frame difference.

  Given what I need to do, I can write some requirements :

  • An encoder which allows me to change some of the parameters (needed for point 2)
  • A language that allows me to work at bit level (needed for points 3 and 5)
  • A language that allows me to build a nice GUI using a designer (GUI is not the core of the project so I can’t afford wasting time by writing one)

  So far my searches have led to mixed results that are not giving me enough resources to start.

  My first find was this MATLAB project which implements MPEG and has some parameters that can be tweaked (like quantization matrix and GOP pattern for example).
  The problem here is that I don’t know MATLAB at all, so I have no idea on how to link everything and build a GUI.

  So the next step was to move to JAVA, and I found a LOT of FFMPEG wrappers, but none seems to allow me to set the parameters that I need. My last try was with Xuggler but the Wiki is down and the documentation does not talk about what I need. Plus, JAVA doesn’t work at bit level so I’d have issues applying the repetition code.

  Failing with JAVA led me to C# and DirectShowNet, but the documentation is quite lacking and I don’t know how to start because I didn’t find anything related to setting the parameters that I need using Filters.

  The question now is : is there any language/framework/platform that allows me to do what I need without having to deal with pure C/C++ ?
  I’d expect a lot of stuff on this matter since we’re talking about well known codecs, still I’m having a hard time finding what I need.

• libavformat/tcp.c : add send_buffer_size and recv_buffer_size options

  19 janvier 2016, par Perette Barella

  libavformat/tcp.c : add send_buffer_size and recv_buffer_size options
  adds two new options that may be set via the dictionary :
   send_buffer_size
  
   recv_buffer_size
  When present, setsockopt() is used with SO_SNDBUF and SO_RCVBUF to set
  
  socket buffer sizes.  I chose to make send and receive independent
  
  because buffering requirements are often asymmetric.
  Errors in setting the buffer size mean the socket will use its
  
  default, so they are ignored.
  There is no sanity checking on values, as the kernel/socket layers
  
  already impose reasonable limits if asked for something crazy.
  Rationale for enlarging receive buffers is to reduce susceptibility
  
  to intermittent network delays/congestion.  I added setting the send
  
  buffer for symmetry.
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] doc/protocols.texi
  • [DH] libavformat/tcp.c

• Senior Software Engineer for Enterprise Analytics Platform

  28 janvier 2016, par Matthieu Aubry — Uncategorized

  We’re looking for a lead developer to work on Piwik Enterprise Analytics core platform software. We have some exciting challenges to solve and need you !

  You’ll be working with both fellow employees and our open-source community. Piwik staff lives in New Zealand, Europe (Poland, Germany) and in the U.S. We do the vast majority of our collaboration online.

  We are a small, flexible team, so when you come aboard, you will play an integral part in engineering. As a leader you’ll help us to prioritise work and grow our community. You’ll help to create a welcoming environment for new contributors and set an example with your development practices and communications skills. You will be working closely with our CTO to build a future for Piwik.

  Key Responsibilities

  • Strong competency coding in PHP and JavaScript.
  • Scaling existing backend system to handle ever increasing amounts of traffic and new product requirements.
  • Outstanding communication and collaboration skills.
  • Drive development and documentation of internal and external APIs (Piwik is an open platform).
  • Help make our development practices better and reduce friction from idea to deployment.
  • Mentor junior engineers and set the stage for personal growth.

  Minimum qualifications

  • 5+ years of experience in product development, security, usable interface design.
  • 5+ years experience building successful production software systems.
  • Strong competency in PHP5 and JavaScript application development.
  • Skill at writing tests and reviewing code.
  • Strong analytical skills.

  Location

  • Remote work position !
  • or you can join us in our office based in Wellington, New Zealand or in Wrocław, Poland.

  Benefits

  • Competitive salary.
  • Remote work is possible.
  • Yearly meetup with the whole team abroad.
  • Be part of a successful open source company and community.
  • In our Wellington (NZ) and Wroclaw (PL) offices : snacks, coffee, nap room, Table football, Ping pong…
  • Regular events.
  • Great team of people.
  • Exciting projects.

  Learn more

  Learn more what it’s like to work on Piwik in our blog post

  About Piwik

  At Piwik we develop the leading open source web analytics platform, used by more than one million websites worldwide. Our vision is to help the world liberate their analytics data by building the best open alternative to Google Analytics.

  The Piwik platform collects, stores and processes a lot of information : hundreds of millions of data points each month. We create intuitive, simple and beautiful reports that delight our users.

  Apply online

  To apply for this position, please Apply online here. We look forward to receiving your applications !