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• Streaming android to windows

  13 juin 2017, par iYehuda

  I’m writing an app that enables controlling android devices from windows machines.
  Major part of controlling the device is viewing it’s screen. Currently, my android app (Java code) captures the screen on a fixed rate, compresses it (JPEG) and sends it, while the windows side (C# code) receives buffers of data, each for frame, decompresses them and displays the last decompressed frame.

  Two issues came up from this solution :

  1. Compression of a single image takes 0.3 seconds, which limits me to low FPS streaming with single thread for compressing. I made a thread pool for compressing captured frames, and it damages the app performance.

  2. The compression is not optimal. The screen can be idle for a while and a continuous transmission of the same frame would be done. Usage of streaming/encoding format would be handful and can ease the network traffic.

  I searched for encoding APIs such as MediaCodec and third party libraries such as ffmpeg. All those libraries encode videos and write them to files (maybe I misunderstood them ?).

  What API can I use for streaming my screen and follow these requirements :

  • Fast encoding / non blocking API
  • Outputs raw binary data for each frame. The data must be sent immediately
  • Can be embedded into my existing applicative protocol (protocol buffers based)
  • Available on C# (Windows) and Java or C++ (Android)

• Piwik analytics database : migrating from MySQL to MariaDB

  11 novembre 2015, par Piwik Core Team — Meta

  This short blog post is an announcement regarding the Piwik technology stack.

  Piwik compatible with MySQL and MariaDB

  Since our first public release Piwik uses the open source database server MySQL to store the analytics data.

  Piwik is also compatible with MariaDB. MariaDB is an enhanced, drop-in replacement for MySQL.

  Upgrading to MariaDB

  Many users from our community as well as Piwik PRO have confirmed that using MariaDB for Piwik has several advantages. MariaDB has in some cases significantly improved query performance and reliability of Piwik. Because MariaDB 5.5 is a complete drop-in-replacement for MySQL 5.5, upgrading can be as easy as running apt-get install mariadb-server (or equivalent for your platform). Existing third party techologies such as TokuDB (FAQ) and Galera are fully compatible with MariaDB.

  Learn more about upgrading to MariaDB : Upgrading from MySQL to MariaDB

  In the future, Piwik will stay compatible with both MySQL and MariaDB.

• Swapping FFMPEG input source

  21 novembre 2017, par stevendesu

  I’m using FFMPEG to stream RMTP to a server. I wish to change what I’m streaming without breaking the connection to this server.

  My current FFMPEG command looks like so :

  ffmpeg -f v4l2 -s 1280x720 -r 10 -i /dev/video0 -c:v libx264 -f flv -r 30 -pix_fmt yuv420p "rtmp://server live=true pubUser=user pubPasswd=pass playpath=stream"

  If I wanted to change from /dev/video0 to /dev/video1 then I need to stop this program and re-run the command swapping out the -i bit.

  Since FFMPEG can read from stdin as well as files, I believe it should be possible to switch the input source on the fly by either piping the output of a different program, or utilizing UNIX sockets. There may also be a solution built into FFMPEG which I’m not aware of.

  My question now is : what’s the simplest / least code / most recommended way of switching these inputs ? Is there a third-party tool that’s recommended ? Does FFMPEG have an alternate command-line parameter I’ve never heard of ? If I do use a UNIX socket of stdin, is there a recommended way to change what’s being written to them ?

  One of my concerns is that if I have FFMPEG read in from a UNIX socket and in a separate shell I have a different instance of FFMPEG writing to this UNIX socket, during the brief period when I’m switching sources the first instance of FFMPEG (which is doing the broadcasting) would die, as it couldn’t find any video data to stream.