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• ffmpeg send intra and gop over a traditionnal tcp (or udp) server

  27 décembre 2015, par the-owner

  The Problem :
  I want to stream a continuous sequence of bitmaps (a video if stuck).
  I want to send the stream over a QTcpSocket/Server (or a QUdpServer why not, or a traditional tcp/udp server), and with the help of ffmpeg librarie.

  Context and Conditions :
  I code in C++, under msvc2013 win-32, QT-IDE, ffmpeg dev 2.8.3.
  We start with a bitmap which is a raw format, a result from GDI+ that I have gotten.
  For very low client connection, so I will use a light video format compression MPEG-1.
  I already have a TCP-Server (QTcpServer), so my goal is to not rebuild another Server for it ...

  Potential algorithm ? :
  I have thought more on the encoding question than the procole one, assume that the protocol could be good.
  It is the very first time that I do it, I don’t want to enroll into something impossible, and obviously I want your insight about this problem which I think since last month (which I have not found a good answer on internet). So, below the outlines of the algorithm that I have imagined :

  Server Side :

  1. I convert the first BMP to YUV format thanks to sws_scale (), we name it P in the following (ffmpeg - libswscale)
  2. I (MPEG1-)encode the picture P (with avcodec_encode_video2()) I get the datas encoded
  3. I serialize the AVFrame/AVpicture P (maybe we will do this step just once)
  4. In the same time I push the datas into a QByteArray (or a simple byte array ?)
  5. I compress P (maybe with QCompress why not)
  6. I send it to the clients.
  7. If the step 6 goes well : we return to number 1 if the next image is a modulus of k, it will be an Intra otherwise a GOP
  8. Otherwise, I wait ? Or I can take into account the lost frame within the code, and I could jump it ? (Inside these question there are questions of server protocols)

  Client Side (summarized)

  1. We get the datas (new Intra or GOP),
  2. We check the error function on the datas received with respect to the other datas received
  3. If the error function return :
  4. "The Error is OK with this new Intra/GOP received" we start decoding them with ffmpeg, and we display the next image of the livestream.
  5. Otherwise, error is not OK, we take the error into account ... (it is not my main problem here)

  Questions :

  It is a solution that I imagined, If the question of server/client protocol are solved, my algorithm is it viable in order to do a livestream ? Could it work ? Is there a better solution ? (another more simpler algorithm or another librarie than ffmpeg for example or something else ?) a link ? Of course critics on my server protocol are welcome.

  I remind, it is just the outlines.

• avcodec/aac_tablegen : get rid of hardcoded tables entirely

  27 novembre 2015, par Ganesh Ajjanagadde

  avcodec/aac_tablegen : get rid of hardcoded tables entirely
  Commit 96786a12f6df26990bbe7c0ca4592b3731724469 makes runtime
  
  initialization cheap.
  Tested with FATE, with/without —enable-hardcoded-tables.
  Reviewed-by : Rostislav Pehlivanov <atomnuker@gmail.com>
  
  Signed-off-by : Ganesh Ajjanagadde <gajjanagadde@gmail.com>
  

  • [DH] libavcodec/Makefile
  • [DH] libavcodec/aac.h
  • [DH] libavcodec/aac_tablegen.c
  • [DH] libavcodec/aac_tablegen.h
  • [DH] libavcodec/aac_tablegen_decl.h
  • [DH] libavcodec/aaccoder.c
  • [DH] libavcodec/aaccoder_trellis.h
  • [DH] libavcodec/aaccoder_twoloop.h
  • [DH] libavcodec/aacenc_utils.h
  • [DH] libavcodec/aactab.c
  • [DH] libavcodec/aactab.h

• 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 !