Video Streaming for ARM

UV4L was originally conceived as a modular collection of Video4Linux2-compliant, cross-platform, user space drivers for real or virtual video input and output devices (with absolutely no external difference from kernel drivers), and other pluggable back-ends or front-ends.

It has evolved over the years and now includes a full-featured Streaming Server component with a customisable web UI providing a set of standard, modern and unique solutions for encrypted live bidirectional data, audio and video streaming, mirroring or conferencing over the web and for the IoT . Since recent releases UV4L has also been providing a RESTful API for the developers who want to implement their custom applications.

HDMI Capturing

The Video4Linux2 uv4l-raspicam driver for Raspberry Pi  has been extended to support the TC358743 HDMI to MIPI converter chip. This chipset is often found in the B101 capture boards made by Auvidea.

Reverse Port Forwarding

On the remote computer

Create a ssh connection to the home computer and start a local ssh server listening on port 2210 on it.

 ssh -R 2210:localhost:22 homeuser@[home-ip]

add –C to activate compression

add -f -N to put the process into the background

On the home computer

Connect to the local ssh server created by the remote connection.

ssh -p 2210 remoteuser@localhost

HowTo build the Marlin 3D Printer Firmware on the Raspberry Pi

If you are already running the excellent octoprint as a printserver on a Raspberry Pi it is very convenient to also build Marlin on it. The new Raspberry Pi Zero W with onboard wifi is at only 10$ just perfect for both tasks. If you want to use the camera streaming of octoprint I would recommend a Pi3 though.

I made a script that sets up the necessary build environment and provides commands for building and uploading. It uses the official Arduino toolchain. Everything is standalone, nothing is installed outside the marlintool directory.

Code

here on github: https://github.com/mmone/marlintool

or download directly as a zip: https://github.com/mmone/marlintool/archive/master.zip

Build configuration

Before first use: Rename the marlintool.params.example file to “marlintool.params”

In its default configuration the script is setup to build the official “Marlin” firmware  but can be easily reconfigured to build any Marlin variant.

Several additional parameters in the “marlintool.params” file allow to adapt the script to your needs.

parameter description
marlinRepositoryUrl The marlin git repository.
marlinRepositoryBranch The branch of the configured repo to use.
marlinDependencies A list of dependencies to download in the format:
[name],[repo url],[library directory](optional).
A library directory should only be specified if the library is not in the root of the repository.
hardwareDefinitionRepo If you build for the Anet board this downloads the necessary hardware definition for the Arduino build environment. If you dont need this set it to an empty string.
boardString The Anet board identifier.
arduinoToolchainVersion The Arduino toolchain version to use. The build platform and architecture are auto detected. At the moment Linux 32 Bit, 64 Bit, ARM and OS X are supported.
port The serialport to use for uploading.
arduinoDir Where to put the Arduino toolchain.
marlinDir Where to checkout Marlin sources.
buildDir The build directory.

Reminder: If you are running octopi on you Raspberry you need to disconnect it from your printer before uploading, otherwise the serial port is blocked.

Note: On OS X due to how the Arduino toolchain is packaged the Arduino splash screen will be displayed even when the toolchain is used from the commandline. This will cause the terminal window you launch marlintool from to lose focus. It also means that a build cannot be launched from a remote ssh session.

Building for Anet Hardware

If you are building the firmware for the Anet A6/A8 you can find suitable example configurations in the Marlin sources at: github.com/MarlinFirmware/Marlin/tree/1.1.x/Marlin/example_configurations/Anet. Just replace the “Configuration.h” and “Configuration_adv.h” in the marlin directory with the files your find there for a good starting point of your configuration.

 

Commandline parameters

-s  — setup

Download and configure the toolchain and the necessary libraries for building Marlin. Also fetches the Anet board hardware definition from github if specified.

-m  — marlin

Download Marlin sources.

-f –fetch

Update an existing Marlin clone.

-v  — verify

Build without uploading.

-u  — upload

Build and upload Marlin. If you are running octopi on you Raspberry you need to disconnect it before uploading otherwise the serial port is blocked.

-b  –backupConfig  [name]

Backup the Marlin configuration to the named backup.

-r  –restoreConfig [name]

Restore the given configuration into the Marlin directory.

-c  — clean

Cleanup everything. Remove Marlin sources and Arduino toolchain.

-p  — port [port]

Set the serialport for uploading the firmware. Overrides the default set in the script.

-h  — help

Show help.

BitTorrent Sync – Serverless Cloud Storage

BitTorrent Sync is what seems to be a great encrypted serverless Dropbox alternative. You can read more about the technical background here. It provides clients on OSX, Linux, Windows, Android, iOS, ARM and others. The client for ARM can easily be run on the Raspberry Pi. Just download the binary and copy it to your pi. Start it by executing “./btsync”. You can now access a web interface at http://[raspberry IP]:8888/gui. This interface allows you to create new “Shares” or connect a local folder to and existing one.

 

Android Ported to C#

Android Ported to C# – Xamarin

Xamarin the company behind Mono the .NET runtime for Linux, iOS, MacOS and Android has just announced that they got the Java part of Android ported to C# via machine translation. They claim some serious performance gains over Dalvik. For them, this is an experiment that they are not planning to focus on, but they will be using some of the technologies in Mono for Android. As Part of the project they improved the automated Java to C# translator “Sharpen”. Their version of Sharpen besides the code of the Android port itself is available on Github.