The second screen world in the Google Cast era

TVs are the biggest, most beautiful screen in people’s living rooms. Google Cast is a technology that enables true multi-screen experiences for the users. Integrating Google Cast into existing applications is simple, and we’re going to cover the SDK and resources available to make your application Cast enabled really easily. Android, iOS and Web. Possibilities? Endless: not only casting video or audio, but also games where the TV becomes the new and high-tech game board or a variety of other apps to enjoy with friends, sitting together on the couch.

(Codemotion Roma 2015)

Raspberry Pi, RPi Camera and Roomba: a first-person experience of the housecleaning

Raspberry and RoombaToday’s challenge

Have a first-person view of the Roomba cleaning, using a RasperryPi, a RPi Camera and some additional stuff.


Raspberry basic configuration

Hardware side, I used the most standard available components: a Raspberry Pi model B, the RPi Camera module and a Edimax EW-7811Un 150Mbps Wi-Fi USB card.

Regarding the OS, there are a lot of distributions available for the Raspberry Pi, but I went for a plan Raspbian: wide support, flexibility, de-facto standard. I installed it using the NOOBS setup, following detailed instruction to load NOOBS image on a sd-card under by Ubuntu pc. Then, started the RasPi, selected Raspbian from the distro installation menu, waited a little bit for the installation to complete.
In the raspi-config app, I enabled the camera and enabled SSH server. Then the usual sudo apt-get update && sudo apt-get -y dist-upgrade && sudo rpi-update && sudo reboot combo, to update everything. The RasPi is ready to rock :)


WiFi setup

Configure the WiFi is easy with the right card (this is an evergreen truth in Linux world). Because the Edimax is supported natively, the only thing I did was:

sudo nano /etc/network/interfaces

and added these lines at the end of file (change them for a different WiFi encryption model). Alternative steps are available too.

allow-hotplug wlan0
iface wlan0 inet dhcp

Reboot and voilà, now the ethernet cable can be unplugged and the RasPi made another step toward movement freedom.


Camera software and configuration

There are different options available. Out-of-the-box, Raspian can both capture still images from camera or recording videos using raspistill and raspivid commands, respectively.

Another option is to use motion as backend to expose the camera video stream. The only problem is that stock version doesn’t (still) support RasPi camera device file, so a big thanks to dozencrows for the fixes has as done. There is a detailed forum post with the final files to replace on the RasPi, plus a couple of tutorials explaining detailed steps to have a working setup, included the sudo apt-get install libjpeg62 part.
With a working motion installation, different frontends can be used to see the camera stream, like the motion server itself, motionEye etc, and the RasPi can even be seen as a normal IP camera from lot of software, included Synology Surveillance Station.
Too lazy to do everything by hand? A complete distro, MotionPie, is an out-of-the-box solution in active development. Flashing the image on a sd-card and reboot the RaspPi is the only requirement, wifi configuration apart.

I found also another project, RaspberrIPCam, a fork of raspivid that offers a working website for accessing the camera stream, Synology Surveillance Station integration and more. Step-by-step guide here.

But, personally and because of the challenge, I chose another way: the project RPi Cam Web Interface.


RPi Cam Web Interface

This solution works in a pretty clever way: instead of using motion infrastructure, it relies on the raspimjpeg command, that is able to capture single frames from the camera stream and its configuration can be changed on the fly writing commands to a Unix pipe. Then motion is configured to point to raspimjpeg output, so it can do all its motion detection magic without a real access to the camera. And Apache serves a micro-site where camera stream is shown and some php scripts glue all together and provide additional features like an easy access to captured video files, changing camera parameters, controlling the entire RasPi from the web interface (included a restart / reboot) and much more.

To install RPi Cam Web Interface, I execute

git clone
cd RPi_Cam_Web_Interface
chmod u+x

and started the whole app (only the first time), using

./ start

The install script allows to customize the Apache directory where all the files are stored changing the rpicamdir variable value in the script itself. Doing so, it’s possible to avoid conflicts with other apps that serve additional pages and sites on the same RasPi. Additional info are available reading the bash file. Use the source, Luke!

To access the website, opening http://raspi_address/ from any browser is enough.

To disable the red light from the camera module, I run

sudo nano /boot/config.txt

and added the following line at the end of file



Roomba setup

Thank to the WiFi, the RasPi could freely connect to the network, and an USB power bank provided the necessary power for the experiment. Scotch tape to assemble everything and here the final result. Pretty cool, isn’t it?

(tinyCam Monitor is responsible for casting the camera stream on the TV, thanks to a Chromecast)


Notes on RPi_Cam_Web_Interface

Some salient parts of RPi_Cam_Web_Interface architecture, mainly to help my memory over time.

motion is configured to read images from local server, using netcam_url http://localhost/cam_pic.php, and this php script returns the content of /dev/shm/mjpeg/cam.jpg file, where raspimjpeg writes the camera preview thanks to the setting preview_path /dev/shm/mjpeg/cam.jpg.
When motion detects something, it executes the command on_event_start echo ‘ca 1’ > /var/www/FIFO, and the corresponding on_event_end echo ‘ca 0’ > /var/www/FIFO when the event ends. /var/www/FIFO is the Unix pipe file used to control raspimjpeg  via the control_file /var/www/FIFO option. Doing so, raspimjpeg creates the video file returned in the web page with all the captured files.
All motion web-service options and recording capabilities are switched off in the config file.

When installing, a link to the camera preview file is created under Apache site directory using the command sudo ln -sf /run/shm/mjpeg/cam.jpg /var/www/$rpicamdir/cam.jpg. In this way, http://raspberry_ip/cam.jpg returns the latest image from the camera, and Android app like tinyCam monitor can points to this address to show camera stream, image by image.

To create Python app that uses the camera, picamera interface can be used.



Environmental variables, API key and secret, BuildConfig and Android Studio

You wanna create an Android app that uses Twittet APIs, so yo need an API key and an API secrets only you and your apps know. Because you need these values inside you app, it’s easy and quick to write them down directly in your source code. But when you commit this code to GitHub (or any other public repo), practically you’re telling your secret keys to entire world. Seems uncommon? Unfortunately, not so much! Same for Dropbox SDK.

One simple way to avoid this bad practice is to store your values inside an environmental variable, so only your machine knows it, then read this values in some way and inject them in your code at build time.
Let’s see how to do that using Android Studio, Gradle, and BuildConfig.

First, we need to create these environmental vars. In Linux and Mac, create or edit the file ~/.gradle/ (pay attention to the actual Gradle User Home directory position) and add some values:

#define your secret values

Second, in your module’s build.gradle file, add these lines

apply plugin: ''
//Add these lines
def TWITTER_CONSUMER_KEY = '"' + TwitterConsumerKeyProp + '"' ?: '"Define Twitter Consumer key"';def TWITTER_CONSUMER_SECRET = '"' + TwitterConsumerSecretProp + '"' ?: '"Define Twitter Consumer secret"';
android.buildTypes.each { type ->

Please note the “TwitterConsumerKeyProp” and “TwitterConsumerSecretProp” have to be the same in both Gradle settings file and Gradle build file.
Finally, to use these values in your code, filled at runtime by Gradle in the build script for you, simply use:

ConfigurationBuilder cb = new ConfigurationBuilder()
    .setOAuthConsumerKey(BuildConfig.TWITTER_CONSUMER_KEY)    .setOAuthConsumerSecret(BuildConfig.TWITTER_CONSUMER_SECRET);

That’s all, then it’s up to you how to create more elaborated configurations. For example, you can have different values based on different android.buildTypes types, or the gradle settings file in a common network folder used by the entire team or…

My Synology DS214play setup

Synology DS214 PlayA NAS is a wonderful beast: you can use it to create your private cloud to store, backup and share your files, as a DLNA media server for smart TVs, as a download station for a variety of different contents and much, much more. True, you can configure your RasPI to do the same job, but appliance solutions are just… Ready to use! In the hard task to pick-up one for my house, my choice, eventually, has gone to Synology DS214play.

Why? Because Synology is a very well known manufacturer of corporate NAS solutions and the software used in the high end products is the same of consumer segment of their offer. Because they have a huge number of clients available for practically all OSes, desktop and mobile, to sync files, watch videos, listen to music, download files, acts as a web, mail, file, git server, IP cams monitoring and much, much more. Because they are easily customizable and there is a vibrant community (even in Italian) of professional and domestic users behind these products. And because the DS214play has an Intel Atom CPU, can transcode 1080p video on-the-flight, has 2 bays for HDs and has an affordable price.


Cloud store, and file sharing

First of all, the NAS can be used as Cloud Station to create a private cloud storage, while the dedicated app  keep in sync your data across different machines (no matter of the OS). Once the router and a dynamic DNS service are configured, data is kept in sync also outside the LAN, so bye bye to Dropbox, Google Drive and any other public cloud services.
In alternative, it is possible to setup a classic rsync flow between a Linux/Mac and the NAS. I used the latter, and now I backup my entire desktop HD to the NAS, and the NAS can then backup its entire content (or part of it) on a cloud backup storage, like S3, Azure and others. Steps to setup rsync, ssh keys and all the whole process are explained here. If ssh connects to the NAS but rsync doesn’t work, Network Backup has to be enabled  via Menu -> Backup & Replication -> Network backup destination -> Enable Network Backup.


Extending the software

SynoCommunityAdditional software could be added using a well-know packages-repositories mechanism. The official repository has some app, but the real magic starts when the SynoCommunity repo is added to the system. Git Server, Horde, ownCloud, CouchPotato, Python, Memcached, Mercurial, Headphones, SABnzbd and many more are all at a click distance now. And they run directly on the NAS, with a lower power consumption compared to a dedicated pc.
It is also possible to create new packages with the help of spksrc, a cross compilation framework intended to compile and package softwares for Synology NAS


Manage movies, TV series and video in general

First solution is to use DS Video, the dedicated client to manage the personal collections of movies, TV series and videos. It’s available via web interface, for mobile OSes and included in some Samsung TVs. ChromeCast is supported, so is possible to browse the movie catalog from web / smartphone /tablet and watch it directly to the TV, without connecting a single cable. Obviously the video format have to be compatible with Chromecast, but it’s always possible to re-encode the video in a supported format (download on a pc, convert, copy back to the NAS).

Plex Media ServerIf DS Video is not enough, Plex Media Server can be installed too, with all the goodies Plex offers :). Once the Plex package has been downloaded, a manual install in the Synology Package center is required. Before doing so, Settings -> General -> Trust Level -> Allow any publisher, otherwise the installation will fail with a “This package does not contain a digital signature” error. Plex server new versions has to be checked from time to time, because it isn’t automatically updated by the Synology Package center. Finally, Plex does not support the hardware transcoding features of the DS214play or DS415play, so up to 720p videos are transcoded, with stuttering and pausing during playback and 100% of CPU usage. But Plex interface is way better than DS Video to me, catalog recognizes a bigger number of videos, so I still prefer to use Plex for browsing and organizing my movies and anime collection.


Music and Photos

I’m not a big user of music (I’ve a Sonos system at home, all the rest is history now), but music works pretty much like movies, with a dedicated app plus some more available from the community. Photos too.


Download station

One of the area where Synology excels is the entire pipeline of scouting, grabbing, downloading, organizing and making available contents. For example, it’s possible to simply add a movie to the IMDb Watchlist and have it automatically downloaded at home, ready to be streamed to the TV via Chromecast. Or as soon as a followed TV series has a new episode aired, it is automagically downloaded on the NAS, with subtitles, ready to be viewed on XMBC, without any intervention. Amazing! :) Let’s see a potential setup for this. Please note that the following steps bring to illegal actions in different countries, so I highly discourage everyone in doing that.

One way for automagically having latest TV series episode without a single interaction, uses a RSS feed technique. On the search results page of Kickass and other services, it’s easy to find an RSS icon that points to an RSS feed with the results of the search. Every time the feed url is loaded, new results can be found inside it, if any.  A specialized service, like showRSS, can create more fine-tuned feeds, with a particular file quality only etc.
The default Download Station app is used to download BT/HTTP/FTP/NZB/Rss feed/eMule files, so the RSS feed url can be added to the app, checking “Automatically download all items” option. Voila’, it works :) A drawback of this approach is that non-useful downloaded files must be manually deleted and subtitles are not downloaded.
If Kickass-like services are banned in a particular country, generally changing the NAS or router DNS and use OpenDNS ( or Google Public DNS (, can workaround the limitation.


A more advance setup for the download station

Sick BeardSick Beard watches for new episodes of favorite TV shows and when they are posted, it downloads, sorts, renames, generates metadata and download subtitles, plus more. It is available as package in the SynoCommunity repo and, once installed (along with Python package), can be configured to use Download Station for downloading snatched files. SABnzbd can work too for nzb files (available in the SynoCommunity repo).
If Sick Beard is unable to communicate with Download Station directly, a Watched folder can be configured in Download Stations under Settings -> BT/HTTP/FTP/NZB -> Location, and SickBeard need to save torrent and nbz files in that folder, under Settings ->Search Settings -> NBZ or Torrent search -> Method: Black hole and selecting the same folder used before. Now Download Station will look for files in that folder, grab them as soon as they’re added by Sick Beard and start the download.
In the Settings, subtitles download can be enabled, while post-processing options are useful to rename and organize files and download metadata (for XMBC, for example) once Download Station has downloaded them.

couchpotatoSimilar approach for movies, this time using CouchPotato. Once installed from the SynoCommunity repo (Python package required too), Settings -> Downloaders -> Black hole directory to communicate directly with the Download Station. Then CouchPotato can be configured to follow IMDb or Movies.IO watchlist, Goodfilms user queue, Rottentomatoes, IMDb, Kinepolis charts and much more.
The potential issues with the standard version of CouchPotato is that it searches only on some newsgroup services, with a limited support for torrents. To solve that, is possible to install the CouchPotato Custom package instead (and Git and Python packages) from the SynoCommunity repo and, during the first launch, specify a github repo with a customized version of CouchPotato. For example, is also able to search on ThePirateBay and KickAssTorrent services. Change DNS as specified above if required.

SickRageIf ThePirateBay and KickAssTorrent are a need also for TV series, the same, “Custom” technique could be used with a fork of Sick Beard, called SickRage. Installation is pretty straightforward: first the Sick Beard Custom package (with Git and Python packages) from the SynoCommunity repo need to be installed and, during its first launch, must be used as Fork URL and master as branch. That’s all, with more detailed instructions in the official forum. Configuration of SickRage follows the same settings of Sick Bears, but now there are a bunch of additional Search Providers to use ;)


The NAS is really a great piece of hardware, and software flexibility allows to use in a variety of different way (what about hosting your WordPress blog there?). Future exploration will bring, for sure, to additional setups (I’ve in mind something for IP cams, for example), so stay tuned!


Ambient sound generators for your concentration

Need some background, natural sound for your coding – browsing – reading sessions? Or a simple, relaxing, white noise generator? There are plenty of sites that offer this service, here some of them:

Rainymood: just open the page and a rainy sounds will start to play. Sometimes, in foggy cities, rain sound is better that a white fog all over you! Similar to Jazz’nd Rain.

Noisli: Set different elements power (water, wind, fire and others) and compose your melody. Available for mobile devices also.

Coffitivity: able to focus only when on a public cafe? Reproduce the same background noise and make things happen! For mobile too.

There are also other sites listed here, ad what about YouTube playlists? Happy listening :)

Fastboot mode for Android Wear devices (G Watch, Gear Live, SmartWatch 3)

Putting Android devices in Recovery mode / Fastboot, when you don’t have access to adb, is an art. And Android Wear, where you have only one button (the power button), adds even more entropy to the whole process.

So let’s gather the different procedures for the different watches.

LG G Watch

  • Find the reset button: it is on the back of the device, near the pins to charge it.
  • Press the button using a paperclip, a SIM ejector or your fantasy
  • Wait for LG logo to appears on screen
  • While the logo is showing, swipe from the top left-hand corner to the the bottom right-hand corner in one, diagonal swipe.
  • From the Fastboot menu, you can launch the Recovery Mode
  • Video


LG G Watch R

  • Turn off the watch and then turn it on normally
  • Wait for LG logo to appears on screen
  • While the logo is showing, swipe from the top left-hand corner to the the bottom right-hand corner in one, diagonal swipe, pressing and holding the power button
  • Alternatively, if the swipe doesn’t work, instead of swiping start tapping the screen with two fingers, one on the top left (10) and one on the bottom right (4), pressing and holding the power button
  • From the Fastboot menu, you can launch the Recovery Mode
  • Video


Samsumg Gear Live

  • Turn off the watch and then turn it on normally
  • Wait for Samsung logo to appears on screen
  • While the logo is showing, swipe from the top left-hand corner to the the bottom right-hand corner in one, diagonal swipe, pressing and holding the power button
  • The bootloader appears
  • Select the Fastboot or Recovery mode swiping downward, and swipe to the right to confirm the selection.


Sony SmartWatch 3

  • Detach any USB cable connected to the watch
  • Turn it off holding the power button and keep holding the button until the watch vibrates three times and then switches it off
  • Press the power button and keep holding. A blue screen that prompts to insert an USB cable will display
  • Double tap the power button
  • A black menu will display, with on-screen instructions
  • Move to Fastboot or Recovery Mode pressing the power button, once a time
  • Select Fastboot (or Recovery) by double pressing the power button


For extreme modding, there is also a third mode available, the Download mode.

New year (not yet), new life (not really), new theme (oh yes)!

A couple of changes happened to this blog: the main language and the theme.

Language: I feel the (fake) need to write to a more international audience, and I need to practice more with English, so the choice is easy ;)

Blog theme: after the first “Rainbowbreeze” theme I’ve created when I moved to WordPress more that 5 year ago, I finally switched to a new theme: DW_Minion by Designwall. Responsive, polish, linear and with still some yellow. Considering my very limited graphic ability, I think this is a good compromise.

Some small changes I applied to the default theme (Appearence -> Customize -> Custom Code -> Header Code):

#secondary {
 display: none;
.primary-inner {
 margin-right: 0;
#post-format {
 display: none;
@media (min-width: 768px) {
 .site-nav .widget {
 padding-top: 20px;
 margin-top: 20px;
.lt-ie9 #page {
 padding: 40px 40px 0;
 margin-left: 40px;
@media (min-width: 1200px) {
 #page {
 padding: 40px 40px 0;
.aktt_credit {

Basically, I totally hidden the secondary (right) column of the theme, some small changes to margins and paddings while on a desktop screen and other minor stuff.

Suggestion on improvements? Let me know!