Advantages of Digital Signage Linux Media Player

What is Linux and where does it differ to Android

To be precise, Linux is only a Kernel. Together with the GNU-Software packeges it forms the unix-like operating system GNU/Linux. This is usually simply known as Linux.

Free and Business Distributors

Several commercial vendors and communities are bringing together easy-to-maintain packages. These are the so-called distributions such as Debian, Arch, Gentoo, Mint, Ubuntu, Red Hat, Suse. Companies like Canonical (Ubuntu), Red Hat or Suse even certify hardware and provide professional long time support.

Lightning-fast Software Installations and Updates

You install and update software packages comfortably with distributions using a package manager. Debian and its derivatives like Ubuntu use apt, for example. A complete office installation takes less than a minute. Updates do not block the system for hours or annoy at startup or shutdown like Windows.

Differences to Android

Android, in smartphones and tablets was developed by Google and is based on Linux kernel. However, the system is conceptually different. For example, it uses another C-Library (Bionic) and most of its apps are based on a special Java runtime called ART (Android Runtime). Because of these differences, most people do not see Android as a classic Linux distribution.

Stability is not the Point

Often, supporters of Linux argue that it is virus-free and stable, but that is too superficial. Other Systems are stable, too. On the contrary! In my opinion this should be a minimal requirement for an operating systems in the 21 century. The time of the regular non-reproducible Windows blue screens has come to an end. The argument of the so-called virus-freedom, in my view, is also misrepresented as each platform is vulnerable.

Stand with Linux Penguin
Digital Signage Linux

The real true advantages of Linux can be reduced to the generic term of freedom. But what does that mean for Digital Signage?

The Advantages

Linux represents a free open source solution. This applies to the development process, the documentation and the software. Therefore, the advantages of Linux go closely hand in hand with those of open source software in general.

Freely configurable

Linux can be configured transparently to the last detail. This makes it possible to customize it precisely according to the customers request. Especially for digital signage players, this provides us with many advantages in terms of security, stability and resource consumption:

A window manager is not necessary

It is possible to build an extremely economical player without a window manager. This means your digital signage player software can also acts as grahical user interface. While running the software, you do not need to worry about any dialogues, error messages or installation instructions on your displays which come from operating system.

In 2008 I worked for a company, which builded digital signage player based on Windows XP. One of the more annoying tasks was to write scripts which suppresses Windows messages. Our customers were not amused when dialogues pop up on their displays during opening hours without any keyboard or mouse plugged in.

While using Linux, such notifications can be redirected to the logs files and become invisible. Grafik does not need a window manager.

Unnecessary services can be removed

The services needed to run are determined by the requirements of your project. Not by the operating system manufacturer. This saves resources, increases stability and security. Each additional component and every service adds complexity to your digital signage system. Additional services may have errors and, in the worst case, become a gateway for viruses or trojans. Fewer additional service you add to your digital signage player, the better it is.

Cost Savings on Hardware

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At the end of the day, the first 3 reasons already save you money. You need less memory and a less powerful CPU for your digital signage hardware.

An extreme example: I got my garlic-player running stably on a 5 EUR Raspberry Pi Zero out of pure curiosity in summer 2016. Even HD videos were played. Try running Windows or Android on such a hardware and play some videos.

Easier Monitoring and Error Analysis

As mentioned in the last paragraph, almost any notification can be redirected to log files. With an easy-to-learn scripting language, it is possible to monitor the state of the system (memory, CPU) and send it regularly to one or more recipients.

There are a lot of small assisting applications existing onboard, which are based on the Unix philosophy. This means they are created to handle only one task, which is done perfectly. However they are designed to cooperate together and can be easily combined. In most cases no extra software has to be purchased or developed.

In case of failure, a technician does not need a VNC, Remote Desktop or Teamviewer. He can analyze and repair the device remotely using a text console. Of course, this also works with a graphical interface.

No necessary for insecure “rooting“

An Android media player must be rooted before being used as an interactive kiosk system. On unix operating systems, root is the administrator. This is the only way to remove the typical Android status bar. This does not only look unprofessional, but also raises the risk of abuse.

The status bar allows the user to exit the kiosk program and access the default Android user interface. To avoid this scenario, additional configurations are necessary. Some manufacturers change the Android operating system to enable an additional configuration in the setups. This makes the status bar disappear. Of course, these changes are incompatible with each other and complicate updates.

In a digital signage network, remote maintenance capabilities are essential. No one wants to send expensive technicians to a device for every little issue. Without root, Android asks the user for confirmation at every reboot or software update.

However, a rooted Android is a problem for security. Root means that any program is able to manipulate foreign files or uninstall software. So, further security measures have to be taken. These in turn increase complexity. More complexity means more possibilities for errors and security holes. A vicious circle!

I therefore consider the use of TeamViewer to be nothing more than a crutch. It not only increases the complexity of the digital signage solution, but also the maintenance effort. Administering a few hundred players with TeamViewer is time-consuming and expensive.

With a digital signage hardware player based on Linux, this effort would not be necessary!

Investment Securities and lesser Dependencies

The Linux source codes are published under a free open source licence which is usually the GPL. That means the source code can be changed or customized whenever you want. Your digital signage solution is not dependent on one vendor (verndor-lock-in) anymore.

He can raise his prices or, in the worst case scenario, discontinue support for his product. In such cases you may face a lot of problems. With Linux and open source you can freely choose a service provider with appropriate knowledge or do the support by yourself.

No Royalties

I would like to address this point only for the sake of adequate understanding, because I personally do not like to use this as the reason. Of course, free open source implies that there are no royalties. Of course, saving money is a plus point.

However, from my point of view in the professional environment everyone should be aware that a support service is always associated with costs. Especially software connected to the Internet has a constant need of care and maintenance. Bugs and vulnerabilities need to be fixed.

The openness of open source grants freedoms with which many dependencies can be reduced. In my opinion, this is the main advantage of Linux and free software. Free and easily availability is a side effect. For example, these are the main reasons for the popularity of the Raspberry Pi.

Practical Digital Signage with Linux

With Linux, efficient digital signage devices can be developed, which are tailored exactly to a customer’s requirement. Also, they are easy to monitor and administer. However, this freedom comes at a price. It is not easy to find devices on the market that fully support Linux.

For PCs with Intel or AMD processors and sufficient budget, this is not a problem. However, many users only want to play HD/4K videos or view images. Small, cost-efficient devices from the Internet of Things (IoT) are sufficient for this purpose. Generally, these devices do not require movable parts such as fans and hardly consume electricity.

On the market, there is a virtually unlimited number of inexpensive media players, especially among East Asian providers. Most of them run Android, but some players have the option to install Linux instead. You should keep a few things in mind during the evaluation.

Bild: Digital Signage Linux Player
Digital Signage Linux Player

Manufacturer Support

Basically, no matter if you choose Android or Linux, make always sure the manufacturer offers regular updates. This is often not the case, especially with cheap devices. It’s hard to get accurate information.

While some vendors specify Linux or Ubuntu support in their specifications, some vendors do not disclose details such as kernel version, video acceleration, or support periods. I. e. You may get devices that run with a kernel version 3.4 (published on May 20, 2012) or Android 4.0 or even older.

Restricted Driver Support

The main reasons for the lack of maintenance are partly because of the manufacturers and the license model of ARM Ltd. ARM Ltd is a British microprocessor supplier who does not produce CPUs but merely designs them.

Companies such as Qualcomm, Samsung, Rockchip, Apple, Intel and many others license a certain processor design and adapt it for their product. The licensees then generally have their “CPUs” produced as “Systems On a Chip” (SoC) in a factory (fab).

Apple A8X ARM Chip
Apple A8X ARM Chip

In contrast to the Linux philosophy, for patent law reasons, the SoC producers offer non-free binary driver versions. Of course, these are not available in the source code. Therefore, they cannot be customized or compiled by others and often work with a certain kernel version. For this reason, such drivers do not enter the so-called upstream or mainline kernel.

But this would be important because only from this original Linux kernel every 8-9 weeks on average new improved versions are released. A free upstream-capable driver in the mainline kernel ensures that the hardware will continue to run flawlessly for future updates in the coming years.

Mystery-Monger

At the same time, device specifications are kept under lock and key for patent reasons. This especially applies for graphics and video processors (GPU/VPU), which are so important to us. ARM (Mali) and other GPU manufacturers such as Imagination (PowerVR) fear that open drivers would tell competitors about the internal functioning of their chips.

This means that even drivers programmed voluntarily by the open source community can only be developed by reverse engineering. That means a big effort. Unfortunately, video acceleration is often missing.

The company Allwinner was a negative example in the past. Although their processors are widely used, software support was more than questionable both legally and technically .

In addition, many Asian low-cost suppliers simply sold the chips to a PCB and do not offer any further support. For a local media player, this may still be okay; for a digital signage network, this is an absolute No-go.

What’s the problem?

The mainline kernel is rapidly evolving. Buyers of poorly supported hardware will remain seated on obsolete non-customizable software. You will no longer be able to benefit from the improvements and bug fixes in the Linux kernel.

If the manufacturer doesn’t care because he doesn’t see it as earning any more money, even serious errors are no longer eliminated. This happens frequently and affects both Android and Linux devices. However, Linux has a large open source community and this can mitigate the consequences over time through reverse engineering.

But corporations like Samsung also declare documentation and specifications to be national secrets. In 2014, we at SmilControl, along with two resellers, tried to get documentation to address the MagicInfo player. At the time, we had customer requests expressing interest in buying Samsung SoC displays if they worked with our CMS. The Samsung representatives either ignored us or we received only meaningless marketing pdf instead of documentation despite NDA.

At the end of the day both customers implemented their own player hardware. Since then we only work on SMIL basis and refuse requests to support proprietary solutions.

Security Costs

For example, BlueBorne became known in September 2017.BlueBorne is a security vulnerability in the Bluetooth stack that affects all systems (Windows, Linux, Android…). In other words, there are already millions of vulnerable devices in circulation that will never fixed because their support period has expired. The only effective protection is to turn off functionality that was once paid for.

Those who run an affected device pool and are dependent on Bluetooth now have two options: Either to live with the vulnerability and the risk associated with it or to scrap working tried-and-tested hardware. This reduces both the cost and life cycle assessments. This could be prevented by more openness amd open source driver. The player hardware would have a longer service life.

The problems with the Bluetooth stack are just one example. The TCP/IP network stack and many other essential components of your digital signage solution may also contain bugs that don't show up until years later.

Botnets

An underestimated and dangerous problem of the lack of sustainability for drivers, especially in the IoT is security. There will be billions of networked devices in the future and thus there is a huge potential for attack vectors. Unfortunately, manufacturers often do not use enough resources to take care for the security issues.

This leads to an unnecessarily high risks, e. g. by creating illegal botnets. These networks send spam, attack other computers or “mines” on the electricity bill of you or your customer’s cryptocurrencies like Bitcoins or Ethereum.

In order to avoid this, quality assurance will become more and more important in the future. But such a thing is complex and expensive. With an open and free open source development process like in Linux, quality assurance could be implemented more effectively. The distributions have been showing us for decades.

Solutions in Sight

Recently, the situation has improved in general. Also with regard to the drivers for the video acceleration, which is so important for Digital Signage. Some chip manufacturers are also rethinking things because of the safety factor mentioned above

Manufacturers with more Support Efforts

For example, Rockchip works with the open source community and releases free and non-free drivers, that are easier to integrate into the mainline kernel.

Broadcom (Raspberry Pi) even finances open source driver development directly.

The same goes for Amlogic, who has been working with the developer company BayLibre for two years to bring their drivers into the mainline kernel.

Reverse-Engineering-Projects

The laborious reverse engineering, e. g. at Sunxi by the open source community with regard to Allwinner chips, is now bearing fruit. The functionality of the CPUs and GPUs (Mali) has now been almost completely decoded.

A crowdfunding campaign to support video acceleration in the mainline kernel for Allwinner CPUs in February 2018 exceeded its financial target after less than 5 days. This means that from June 2018 onwards, all-winner CPUs could receive the long-awaited free video acceleration by default – even without manufacturer support.

Thanks to the Freedreno kreverse engineering project, Qualcomm Adreno GPUs will be able to accelerate video playback under Linux by default. Even Google and Qualcomm are now working with the Community, to get the drivers of the latest Snapdragon 845 into the Linux-Mainline-Kernel

Effects on the Digital Signage Player Hardware Industry

Our industry will benefit from these developments in the long term. In the future, Linux will make it possible to operate far more cost-effective digital signage player hardware more conveniently over an extended period of time. Many project requirements do not always require the latest octa-core processor. An older tried and tested generations of processors such as an A10 can be perfectly sufficient.

If this is perfectly supported by open source software in the coming years, we will save acquisition and operating costs. For example by means of well-adapted power-saving functions. In addition, we also do something for ecological sustainability, save resources and help to avoid e-waste.

It is readily possible to tailor and market distributions specific to digital signage solutions. Multi-vendor alliances establish universal standards, such as SMIL.

With our buying decisions for open source, we can also force suppliers to be more sustainable and open-minded. The Raspberry Pi enjoys great popularity despite its comparably weak hardware. A reason for this is that it was almost completely open from the beginning, except for the GPU firmware.

However, in my opinion, a Raspberry Pi can only be used as a digital signage device to a limited extent.

Conclusion: Linux as base for Digital Signage Hardware

Running low-cost digital signage player hardware under Linux is still difficult, but the situation is steadily improving. Unfortunately, it still requires more effort and research than is actually necessary

However, there are clear rays of hope and the future gives reasons for hope. Based on the above developments, the following years could be more and more interesting in terms of digital signage player hardware.

Image Video wall Monitorwand
Digital Signage Hardware Video Wall

For Linux Digital Signage Player hardware with Rockchip CPU, it is recommended to consider the 4K-capable Rk3288 or the 64 bit RK3399.

So there are definitely more alternatives than just the Raspberry Pi or catastrophically supported Android devices. The effort to install the free operating system is definitely worth it. Open source offers more possibilities to assemble and administer secure digital signage Linux hardware at low cost. The cherry on top is the reduced dependency on one manufacturer. You get full control over your devices.


Gravatar Nikolaos Sagiadinos
Author: Niko Sagiadinos
Specialized on Digital Signage Software
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