Here is a curated list of active, responsive and valid BitTorrent trackers. Add them to the list of trackers of your torrents to increase your chance of finding peers and improve download speed.(more…)

There was a time that Apple macOS was the best platform to handle multimedia (audio, image, video). This might be still true in the GUI space. But Linux presents a much wider range of possibilities when you go to the command line, specially if you want to:

Process hundreds or thousands of files at once

Same as above, organized in many folders while keeping the folder structure

Same as above but with much fine grained options, including lossless processing, pixel perfectness that most GUI tools won’t give you

The Open Source community has produced state of the art command line tools as ffmpeg, exiftool and others, which I use every day to do non-trivial things, along with Shell advanced scripting. Sure, you can get these tools installed on Mac or Windows, and you can even use almost all these recipes on these platforms, but Linux is the native platform for these tools, and easier to get the environment ready.

These are my personal notes and I encourage you to understand each step of the recipes and adapt to your workflows. It is organized in Audio, Video and Image+Photo sections.

I use Fedora Linux and I mention Fedora package names to be installed. You can easily find same packages on your Ubuntu, Debian, Gentoo etc, and use these same recipes.

Audio

Show information (tags, bitrate etc) about a multimedia file

ffprobe file.mp3

ffprobe file.m4v

ffprobe file.mkv

Lossless conversion of all FLAC files into more compatible, but still Open Source, ALAC

Has been said the Fraunhofer AAC library can’t be legally linked to ffmpeg due to license terms violation. In addition, ffmpeg’s default AAC encoder has been improved and is almost as good as Fraunhofer’s, specially for constant bit rate compression. In this case, this is the command:

Same as above but under a complex directory structure

This is one of my favorites, extremely powerful. Very useful when you get a Hi-Fi, complete but useless WMA-Lossless collection and need to convert it losslesslly to something more portable, ALAC in this case. Change the FMT=flac to FMT=wav or FMT=wma (only when it is WMA-Lossless) to match your source files. Don’t forget to tag the generated files.

Convert APE+CUE, FLAC+CUE, WAV+CUE album-on-a-file into a one file per track ALAC or MP3

If some of your friends has the horrible tendency to commit this crime and rip CDs as 1 file for entire CD, there is an automation to fix it. APE is the most difficult and this is what I’ll show. FLAC and WAV are shortcuts of this method.

Make a lossless conversion of the APE file into something more manageable, as WAV:

ffmpeg -i audio-cd.ape audio-cd.wav

Now the magic: use the metadata on the CUE file to split the single file into separate tracks, renaming them accordingly. You’ll need the shnplit command, available in the shntool package on Fedora (to install: yum install shntool). Additionally, CUE files usually use ISO-8859-1 (Latin1) charset and a conversion to Unicode (UTF-8) is required:

It is not UTF-8 encoded, it is some ISO-8859 variant, which I need to know to correctly convert it. My example uses a Brazilian Portuguese subtitle file, which I know is ISO-8859-15 (latin1) encoded because most latin scripts use this encoding.

Now we are ready to add them all to the movie along with setting the movie name and embedding a cover image to ensure the movie looks nice on your media player list of content. Note that this process will write the movie file in place, will not create another file, so make a backup of your movie while you are learning:

You’ll get a directory tree with decrypted VOB and BUP files. You can generate an ISO file from them or, much more practical, use HandBrake to convert the DVD titles into MP4/M4V (more compatible with wide range of devices) or MKV/WEBM files.

Convert 240fps video into 30fps slow motion, the loss-less way

Modern iPhones can record videos at 240 or 120fps so when you’ll watch them at 30fps they’ll look slow-motion. But regular players will play them at 240 or 120fps, hiding the slo-mo effect.

We’ll need to handle audio and video in different ways. The video FPS fix from 240 to 30 is loss less, the audio stretching is lossy.

# make sure you have the right packages installed
dnf install mkvtoolnix sox gpac faac

1 Photo + 1 Song = 1 Movie

The above method will create a very efficient 0.2 frames per second (-framerate 0.2) H.264 video from the photo while simply adding the audio losslessly. Such very-low-frames-per-second video may present sync problems with subtitles on some players. In this case simply remove the -framerate 0.2 parameter to get a regular 25fps video with the cost of a bigger file size.

The -vf scale=960:-1 parameter tells FFMPEG to resize the image to 960px width and calculate the proportional height. Remove it in case you want a video with the same resolution of the photo. A 12 megapixels photo file (around 4032×3024) will get you a near 4K video.

There is also a more efficient and completely lossless way to turn a photo into a video with audio, using extended podcast techniques. But thats much more complicated and requires advanced use of GPAC’s MP4Box and NHML. In case you are curious, see the Podcast::chapterize() and Podcast::imagify() methods in my music-podcaster script. The trick is to create an NHML (XML) file referencing the image(s) and add it as a track to the M4A audio file.

-Directory, -FileName and -RegionName specify the things you want to see in the output. You can remove -RegionName for a cleaner output.
The -r is to search recursively. This is pretty powerful.

Make photos timezone-aware

Your camera will tag your photos only with local time on CreateDate or DateTimeOriginal tags. There is another set of tags called GPSDateStamp and GPSTimeStamp that must contain the UTC time the photos were taken, but your camera won’t help you here. Hopefully you can derive these values if you know the timezone the photos were taken. Here are two examples, one for photos taken in timezone -02:00 (Brazil daylight savings time) and on timezone +09:00 (Japan):

This shows that the local time when the photo was taken was 2013:10:12 23:45:36. To use exiftool to set timezone to -02:00 actually means to find the correct UTC time, which can be seen on GPSDateTime as 2013:10:13 01:45:36Z. The difference between these two tags gives us the timezone. So we can read photo time as 2013:10:12 23:45:36-02:00.

The source code currently brings to life (as an example), integrated with some Bluemix services and Docker infrastructure, a PHP application (the WordPress popular blogging platform), but it could be any Python, Java, Ruby etc app.

Before we start: understand Bluemix 3 pillars

I feel it is important to position what Bluemix really is and which of its parts we are going to use. Bluemix is composed of 3 different things:

Bluemix is a hosting environment to run any type of web app or web service. This is the only function provided by the CloudFoundry Open Source project, which is an advanced PaaS that lets you provision and de-provision runtimes (Java, Python, Node etc), libraries and services to be used by your app. These operations can be triggered through the Bluemix.net portal or by the cf command from your laptop. IBM has extended this part of Bluemix with functions not currently available on CloudFoundry, notably the capability of executing regular VMs and Docker containers.

Bluemix provides pre-installed libraries, APIs and middleware. IBM is constantly adding functions to the Bluemix marketplace, such as cognitive computing APIs in the Watson family, data processing middleware such as Spark and dashDB, or even IoT and Blockchain-related tools. These are high value components that can add a bit of magic to your app. Many of those are Open Source.

UI to build, manage and execute the app delivery pipeline, which does everything needed to transform your pure source code into a final running application.

The Track & Plan module, based on Rational Team Concert, to let your team mates and clients exchange activities and control project execution.

This tutorial will dive into #1 and some parts of #3, while using some services from #2.

The architecture of our app

When fully provisioned, the entire architecture will look like this. Several Bluemix services (MySQL, Object store) packaged into a CloudFoundry App (bridge app) that serves some Docker containers that in turns do the real work. Credentials to access those services will be automatically provided to the containers as environment variables (VCAP_SERVICES).

Structure of Source Code

The example source code repo contains boilerplate code that is intentionally generic and clean so you can easily fork, add and modify it to fit your needs. Here is what it contains:

bridge-app folder and manifest.yml file

The CloudFoundry manifest.yml that defines app name, dependencies and other characteristics to deploy the app contents under bridge-app.

containers

Each directory contains a Dockerfile and other files to create Docker containers. In this tutorial we’ll use only the phpinfo and wordpress directories, but there are some other useful examples you can use.

.bluemix folder

When this code repository is imported into Bluemix via the “Deploy to Bluemix” button, metadata in here will be used to set up your development environment under DevOps Services.

admin folder

Random shell scripts, specially used for deployments.

Watch the deployment

The easiest way to deploy the app is through DevOps Services:

Click to deploy

Provide a unique name to your copy of the app, also select the target Bluemix space

The idea is to encapsulate all these steps in code so deployments can be done entirely unattended. Its what I call brainless 1-click deployment. There are 2 ways to do that:

A regular shell script that extensively uses the cf command. This is the admin/deploy script in our code.

An in-code delivery pipeline that can be executed by Bluemix DevOps Services. This is the .bluemix/pipeline.yml file.

From here, we will detail each of these steps both as commands (on the script) and as stages of the pipeline.

Instantiation of external services needed by the app…

I used the cf marketplace command to find the service names and plans available. ClearDB provides MySQL as a service. And just as an example, I’ll provision an additional Object Storage service. Note the similarities between both methods.

Creation of an empty CloudFoundry app to hold together these services

The manifest.yml file has all the details about our CF app. Name, size, CF build pack to use, dependencies (as the ones instantiated in previous stage). So a plain cf push will use it and do the job. Since this app is just a bridge between our containers and the services, we’ll use minimum resources and the minimum noop-buildpack. After this stage you’ll be able to see the app running on your Bluemix console.

Creation of Docker images

The heavy lifting here is done by the Dockerfiles. We’ll use base CentOS images with official packages only in an attempt to use best practices. See phpinfo and wordpress Dockerfiles to understand how I improved a basic OS to become what I need.

The CCS_BIND_APP on the script and BIND_TO on the pipeline are key here. Their mission is to make the bridge-app’s VCAP_SERVICES available to this container as environment variables.

In CloudFoundry, VCAP_SERVICES is an environment variable containing a JSON document with all credentials needed to actually access the app’s provisioned APIs, middleware and services, such as host names, users and passwords. See an example below.

A container group with 2 highly available, monitored and balanced identical wordpress containers

See the results

At this point, WordPress (the app that we deployed) is up and running inside a Docker container, and already using the ClearDB MySQL database provided by Bluemix. Access the URL of your wordpress container group and you will see this:

Bluemix dashboard also shows the components running:

But the most interesting evidence you can see accessing the phpinfo container URL or IP. Scroll to the environment variables section to see all services credentials available as environment variables from VCAP_SERVICES:

So I’m using sed, the text-editor-as-a-command, to edit WordPress configuration file (/etc/wordpress/wp-config.php) and change some patterns there into appropriate getenv() calls to grab credentials provided by VCAP_SERVICES.

Dockerfile best practices

The containers folder in the source code presents one folder per image, each is an example of different Dockerfiles. We use only the wordpress and phpinfo ones here. But I’d like to highlight some best practices.

A Dockerfile is a script that defines how a container image should be built. A container image is very similar to a VM image, the difference is more related to the file formats that they are stored. VMs uses QCOW, VMDK etc while Docker uses layered filesystem images. From the application installation perspective, all the rest is almost the same. But only only Docker and its Dockerfile provides a super easy way to describe how to prepare an image focusing mostly only on your application. The only way to automate this process on the old Virtual Machine universe is through techniques such as Red Hat’s kickstart. This automated OS installation aspect of Dockerfiles might seem obscure or unimportant but is actually the core of what makes viable a modern DevOps culture.

Being a build script, it starts from a base parent image, defined by the FROM command. We used a plain official CentOS image as a starting point. You must select very carefully your parent images, in the same way you select the Linux distribution for your company. You should consider who maintains the base image, it should be well maintained.

Avoid creating images manually, as running a base container, issuing commands manually and then committing it. All logic to prepare the image should be scripted in your Dockerfile.

In case complex file editing is required, capture edits in patches and use the patch command in your Dockerfile, as I did on wordpress Dockerfile.
To create a patch:

diff -Naur configfile.txt.org configfile.txt > configfile.patch

Then see the wordpress Dockerfile to understand how to apply it.

Always that possible, use official distribution packages instead of downloading libraries (.zip or .tar.gz) from the Internet. In the wordpress Dockerfile I enabled the official EPEL repository so I can install WordPress with YUM. Same happens on the Django and NGINX Dockerfiles. Also note how I don’t have to worry about installing PHP and MySQL client libraries – they get installed automatically when YUM installs wordpress package, because PHP and MySQL are dependencies.

To chose to go with Docker in some parts of your application means to give up some native integrations and facilities naturally and automatically provided by Bluemix. With Docker you’ll have to control and manage some more things for yourself. So go with Docker, instead of a buildpack, if:

If you need portability, you need to move your runtimes in and out Bluemix/CloudFoundry.

If a buildpack you need is less well maintained then the equivalent Linux distribution package. Or you need a reliable and supported source of pre-packaged software in a way just a major Linux distribution can provide.

The best balance is to use Bluemix services/APIs/middleware and native buildpacks/runtimes whenever possible, and go with Docker on specific situations. Leveraging the integration that Docker on Bluemix provides.

I’ve searched for a long time and finally found a US regular bank that will let me open a free checking account. It is BBVA Compass bank.

All these services are free: ATM withdraw and deposit (BBVA’s and AllPoint ATMs), full featured Internet banking, full featured mobile banking, Visa debit card, Apple Pay and more. The non-free services are listed here and exact rates depend on the US state where the account was opened.

To open a checking account, you must personally visit a physical branch in US and spend 40 minutes on an interview. You will leave the branch with an open account and routing numbers containing a $26 balance plus valid user and password that can be used on BBVA’s app and Internet banking. Free Visa debit card will arrive to some US address in a week or two, so no ATM until then.

They have 2 free checking account types. You should chose the one that includes free or charge AllPoint ATM usage which are very popular throughout US, and can be found in almost every 7 Eleven store. Use the AllPoint app to find one near you. (more…)

WordPress is packaged for Fedora and can be installed as a regular RPM (with DNF/YUM). The benefits of this method are that you don’t need to mess around with configuration files, filesystem permissions and since everything is pre-packaged to work together, additional configurations are minimal. At the end of this 3 minutes tutorial, you’ll get a running WordPress under an SSL-enabled Apache using MariaDB as its backend.

On December 3 Apple has open sourced the Swift programming language on Swift.org. The language was first released (not Open Source yet) about the same time as iOS 8 and was created by Apple to make Mac and iOS app development an easier task. Swift is welcome as one more Open Source language and project but is too early to make a lot of noise about it. Here are my arguments: (more…)

I don’t know about you senior bloggers but I’m starting to hate the way the WordPress community has evolved and what it became.

From a warm and advanced blogging software and ecosystem it is now an aberration for poor site makers. Themes are now mostly commercial, focused on institutional/marketing sites and not blogs anymore. WordPress is simply a very poor tool for this purpose. You can see this when several themes are getting much more complex than WordPress per se. (more…)

Before iOS 8, the Polar H7 heart sensor with bluetooth needed special apps to pair. Now it pairs natively on the Settings app and starts sending heart rate to the new Health app on iOS 8, which will keep recording the data and building a graph like this:

At the Fedora 20 release party another guy stepped up and presented+demonstrated OpenShift, which was the most interesting new feature from Red Hat for me. First of all I had to switch my mindset about cloud from IaaS (infrastructure as a service, where the granularity are virtual machines) to PaaS. I heard the PaaS buzzword before but never took the time to understand what it really means and its implications. Well, I had to do that at that meeting so I can follow the presentation, of course hammering the presenter with questions all the time.(more…)

Few weeks ago I attended the Fedora 20 release party at São Paulo Red Hat offices. It was nice to hang together with other Fedora enthusiasts, get a refresh about newest Fedora features and also share my experiences as (I considere myself) a power user.

For some reason nobody published a simple guide like this. Maybe nobody tryied this way. I just tryied and it works with OS X Mountain Lion on a Mid 2012 MacBook Air.

If you have a Mac computer or laptop and want to install OS X, and all that you have is the operating system installation ISO image, you just need an external USB storage (disk or pen drive) of 5GB minimum size. Those regular 120GB or 1TB external disks will work too.

Just remember that all data on this external storage will be erased, even if the Mac OS X installation ISO is just 4.7GB. So make a backup of your files and after installtion you can re-format the external disk and recover the files on it.

To make the OS X installation ISO image file usable and bootable from the external storage, use the Mac OS terminal app or, on Linux, use the command line. This is the magic command:

dd if="OS X Install DVD.iso" of=/dev/disk1 bs=10m

You might want to change the red part of this command to the disk name that you get when inserted the external storage. Remember to not use things like disk1s1 or, on Linux, sdc1. The highlighted blue part on these examples are the partition name, and you don’t want that. You want to use the whole storage, otherwise it will not boot the computer.

After the command finishes execution, boot the Mac computer with the alt/option key pressed. Several devices will appear on screen for you to choose wich one to boot. Select the one with the USB logo and called “EFI Boot“.

Mac OS X installation app will boot and you can start the process. Remember that the default behavior here is to upgrade the installed system. If you want a clean install, select the Disk Utility app on the menu and make sure you erase and create a new partition on the Mac internal storage.

As a side technical note, this is all possible because ISO images — primarily designed for optical disks — can also be written to regular other storages as pen drives. And Apple has also put the right bits on these ISO images to allow it to boot from non-optical disks too.