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Android TV as HTPC

The dumb TVs have slowly given up their place to so-called smart TVs, not much different of how dumb phones were (relatively quickly rather) slowly replaced by smartphones. Basically a smart TV is a traditional TV with integrated features once found in set-top boxes. Though initially every manufacturer was using their own proprietary firmware, Android, the dominant (by installed base) operating system in smartphones, has, also, taken its place on most new smart TVs.

Android TV refers to the Android builds running on set-top boxes, plug-in sticks, and TVs but can simply refer to the TVs running it. It actually is a successor to Google TV, a similar platform but not that tied to Android. Interestingly the first devices running Google TV were x86-based making them basically personal computers hidden in plain sight. Later devices and every Android TV is ARM-based making them more like big Android tablets with TV remote control rather touch input and TV tuner.

Home-theater PC or HTPC refers to a personal computer with software for media playback and recording that integrated with a home entertainment system. Those computers basically run a specialized application, called media center software, on top of a common operating system (Windows or Linux). The software basically made the device usable with a remote controller providing a convenient interface as the one smart TVs have. In the past they’re predominantly traditional x86 computers but nowadays ARM is common thanks to the popularization of low-cost low-consumption ARM computers such as Raspberry Pi. Videogame consoles were also commonly used for this position, at least my PS3 did for a long time (thanks to Movian and multiMAN’s NTFS support for external HDD).

Wireless adb

The Android Debug Bridge or adb is a tool allowing communication with an Android device. Among the variety actions allowed it can be used to exchange files, app installation and Unix shell access on the device. It normally works over wired connection something not convenient with a TV, but can also be used over Wi-Fi.

NixOS users can enable it adding the following in system configuration. This also installs and the required udev rules for smartphones. Not that important in our case.

  programs.adb.enable = true;
  users.users.user.extraGroups = [ ] ++ "adbusers"

To enable it on TV, you’ve to open Settings > Device Preferences > About. Scroll down to ‘Build’, then click it a bunch of times until the message “You are a developer” appears. Now go to Settings > Preferences > Developer options > USB debugging and enable the option. Finally, Setting > Network & Internet > active connection, and note the IP address.

The connection can be done using the following command, where IP=192.168.1.2 the IP found previously. A prompt requesting access will appear on TV.

adb connect 192.168.1.2

Files can be sent with

adb push /path/to/file/to/sent /mnt/sdcard/

Programs can be installed with

adb install /path/to/downloaded/program.apk

A Unix shell can be opened with

adb shell

Alternative input methods

TV remote controllers aren’t always the best input. Especially when having to write anything such as in a search box. Android TVs support Bluetooth keyboards just fine. Rather getting one an alternative will be using a smartphone as keyboard or sending input from laptop.

The simplest solution for the first is using the official Android TV Remote Control app. It allows three functionalities, (i) dpad navigation, (ii) touchpad input, and (iii) keyboard input. It can work over Bluetooh but can also work over Wi-Fi as long as the two devices are in the same network. Also some apps may offer a second screen experience utilizing the Nearby API. Those will prompt a user to initiate connection on smartphone and further interaction will proceed on smartphone.

The second comes a bit unexpected. Android usually run on smartphones and therefore people primarily wanted a way to control their PC from the smartphone rather their smartphone from PC. Therefore there aren’t many solutions for this. Text input at least can easily be send using adb as follows

adb shell input text "text to send"

It also has commands for sending keyevents and taps but isn’t very user-friendly. Touch taps specifically require the exact screen coordinates to be supplied making it tedious at least. Schedenig Marian made a wrapper that doesn’t only allow sending the previous commands conveniently but also shows the display (kinda laggy). Basically it’s like an Android emulator running but is connected to a device over adb. Though made for debugging a broken smartphone it applies to this case as well.

Download from previous page, unzip and run the following command in the unzipped folder.

#!/bin/sh
mkdir -p /home/$USER/.cache
cat <<EOF > config.properties
	adbCommand = `which adb`
	screenshotDelay = 100
	localImageFilePath = /home/$USER/.cache/adbcontrol_screenshot.png
	phoneImageFilePath = /mnt/sdcard/adbcontrol_screenshot.png
EOF

Then, having a Java runtime installed

java -jar adbcontrol.jar

File manager

Like smartphones or/and tablets the pre-installed file manager is very barebones. There’re a few good file managers. Unfortunately none of them is free as in freedom. The one I’ll recommend is File Commander. It is freeware (ad-supported), feature-rich, has a traditional interface making it braindead simple to use, and supports FTP and SMB. More interestingly it integrates another functionality usually provided by another app which has no good contenders for the place. That functionality is file transfer by allowing access to device files and upload through a web browser. Another option is FX File Explorer which has a more modern interface but all its advanced features and networking functionality requires payment.

As both apps are on store, their file sharing capabilities can be used to send apks and install them on device rather using the adb shown previously.

Web browser

There’re uses for a web browser even on an HTPC, such as checking the router panel or various media-related sites. During the move from Google TV to Android TV, Chrome got removed from the default installation leaving Android TV without a web browser. Basically the Play Store doesn’t have any of the popular Android browsers found in smartphones. Instead it only a has handful ones specifically designed for Android TV. I found none of them good and had issues with all that I tried. Also, none of them is free (as in freedom).

Both Chromium and Firefox can be sideloaded onto an Android TV device but none of them has a suitable interface. Nevertheless there’s an official Firefox for Fire TV version. Fire TV is an Amazon brand which functions identical to Android TV, and Fire OS is basically Android-based and for time being Android compatible. Therefore Firefox for Fire TV can run fine on Android TVs.

Someone has to download the (latest available) apk from the releases page and then install it either using adb or sending it on TV by other means (see previous section).

Media player

The most basic functionality a HTPC requires is media playback. Again, a pre-installed media player is usually available but is very simple. One of the most popular media players on computers, VLC, is also available for Android with a TV-suitable interface available. It can be installed from the Store or downloaded from the official site and installed using adb or sending it on TV and installing it there. VLC allows adding and reading (S)FTP(S), SMB, and NFS locations.

Though I used VLC for long time, some years after moving on Linux I started using mpv, a CLI-first keyboard-driven application lacking a traditional interface. It is a fork of (short lived) mplayer2 that in turn is a fork of venerable (and still alive) MPlayer which predates VLC itself. Both mpv (and ancestors) and VLC essentially depend on ffmpeg. An unofficial Android port exists called mpv-android. It can be installed by downloading it from releases page. Unlike its computer counterpart it has a minimal GUI to allow opening files (only from internal storage) and editing some configuration. In order to play from external storage or a network location it has to be opened from a file managers (which for the later it has to be supported from the manager).

Streaming

Looking for content to watch on TV is a hassle. What is the most usual entertainment is search film on computer, add it on queue on a service with available app, then open app, and start watching. Basically TV interfaces are difficult to search content on. That is how Chromecast came to be. It cuts the part where you need to open an app or even requiring a device that supports apps at all. Specifically it started as an HDMI toggle which streams video (or music) off the internet. Android TVs have Chromecast support built-in. A Chromium-based browser should be used on computer or Firefox with fx_cast. On supported sites an “cast button” appears which can be clicked to make the TV stream the video. At that point the page on the computer doesn’t have to remain open.

Chromecast can also be used to stream a local file from computer. It can either be done using VLC (on desktop) or the Videostream app on Chrome. For VLC, open the program then from menus Playback > Renderer > appropriate Chromecast device, and finally start playing a video or audio file. The file will begin playing on the TV. The VLC controls continue working as they’re for a file rendered locally. To run Videostream after being installed on Chromium the following script can be used to run it without having to open from within the browser.

#!/bin/sh
chromium --enable-nacl --profile-directory=Default --app-id=cnciopoikihiagdjbjpnocolokfelagl

Media center

Though using a file manager, a media player, and various apps is a way to use an Android TV, thanks to its interface (basically the entire system functions as a media center) another is the more traditional way of installing a dedicated media center software that integrates all the functionality in a single program. Most popular one among them, Kodi. Kodi is an open source home theater software that is media player designed to work from small screens such as phones to big ones like TVs. The reason for its popularity is its vast customizability with skins and plug-ins allowing access to streaming services. It even has PVR functionality but as there’s no front-end to Android TV Input Framework this doesn’t work for OTA broadcasting. It can either be downloaded from Store or the releases on the official site.

Media sharing

Till here all is nice if storage is mounted directly on the device or is network accessible. The problem is what to do when none of those happen. Specifically suppose you’ve some media files on the laptop you want to watch on TV. The options shown are, (i) send the file on TV and (ii) Chromecast. The first is ridiculous whereas the second is computer-first approach. If things are organized and searching isn’t required, the media center interface is kinda comfy making casting unnecessary.

The solution is setting up a server on laptop or/and other devices, that is making the devices network accessible. This is a bit of hassle. A simpler solution is using software meant for this purpose, employing a client-server model.

The first and more popular software to do this is Plex, a proprietary freemium system and nowadays ad-supported streaming service as well. It is actually a media player with client-server model originating from Kodi (then known as XMBP). Though very polished, my media server software of choice is Jellyfin. Jellyfin is a fork of, formerly mostly open-source with closed-source components and now proprietary, Emby which was originally made as a own-content-only Plex alternative with plug-in support. Jellyfin for TV can be downloaded from Store or the releases.

Both require a media server to be setup on devices which hold the media. Let’s move a bit further than what a vanilla HTPC is supposed to do to what is usually expected to do. It shouldn’t be capable of media playback but also allow access to its media to other devices. Concluding, we’ll require to set-up a server on two devices which can be complicated. The solution is a program that functions both as a server and as a player that makes media sharing seamless.

That program is, the mentioned in previous section, Kodi. Kodi can be used as an UPnP client that can receive music and video from a UPnP server on the network, but can also be used as a UPnP server itself that will stream its library contents to other players on the network.

Issues

In contrast to what this post’s title is, this is in no case a replacement for a standalone HTPC. There’re many issues arising. From Android’s architecture that limits the software that runs on it to Android TV firmware itself being broken usually thanks to manufacturers. One that is made obvious in this post is the limited availability of relevant software. This was to be expected since as I mentioned in the beginning Android TVs can be regarded as big tablets meaning it comes with all idiosyncrasies a tablet has… and more.

Another is framebuffer being limited to resolution (1080p) smaller than TV’s native resolution (4K). Meaning the UI is rendered at 1080p and then gets upscaled to 4K. That means apps are locked to running to a lower resolution. Utilizing a specific API it is possible to render video to the 4K output directly. Unfortunately all apps mentioned in this post don’t and only a handful do such as YouTube and Netflix.

Others are codec issues. ARM CPUs installed on TVs aren’t M1-level beasts by any margin, meaning that videos with encodings not having hardware acceleration will be hard to run if run at all. Also high-quality configurations used at mpv on desktop will’ve difficulty to run in any case. On topic of quality, lack of x86 and Windows also means no madVR possibility.

Beyond any issues, a smart TV and stand-alone NAS is simpler, cheaper and more than enough for most users than building a HTPC. And with the move to streaming rather using local content the NAS is also unneeded.

TODO: Provide instructions for setting up Kodi and Jellyfin.

TODO: Provide instructions for running a server PC-side.

TODO: Provide instructions for setting up a NAS.