Notes on hacking various Android-based media devices
Theatres, immersive experiences, and escape rooms are increasingly making use of video effects displayed on monitors and screens or projected onto surfaces. These would ideally be controlled via centralised show control software which could either deliver media over a network, or at least send a signal to trigger playback of a local media file.
| Device | Cost | Notes |
|---|---|---|
| Sprite |  |
Can be paired with ESP32/Arduino to trigger network playback |
| Raspberry Pi | |
Requires RPi4/5 for reliable 1080p playback |
| NUC PC + VLC etc. |  |
Most powerful, possible dual HDMI output, but also most expensive |
| Android-based "HD Media Player" |  |
Cheapest |
There are many "Media Players" available on AliExpress etc. which are running some variant of the Android operating system and would seem to have all the hardware required - they have (normally wireless, sometimes wired) network connection, HDMI output, can access media on USB storage. The problem is that they are not designed to be controlled by anything other than their supplied IR remote. One alternative then is to use an IR blaster device to clone and replay the command signals sent by the controller. Another is to try to modify and control the built-in Android operating system to remotely trigger playback of files from the USB/SD storage.
Note that Amazon Fire sticks etc. do not generally have any local storage, nor the ability to load files from USB storage.
- External USB support can be added using https://www.amazon.co.uk/Power-Cable-Firestick-Lite-Cube-Black/dp/B07XTSQ8ZY
- Wired ethernet support can be added using https://www.amazon.co.uk/Ethernet-Adapter-Compatible-Chromecast-Streaming-1PCS/dp/B0GR8WM124
This is running a cut-down version of Android that has ADB access already authorised, which means it's possible to connect to and control over a network using ADB. Set up the projector to access the local Wi-Fi, and take a note of the assigned IP address. Then issue ADB commands from a PC on the same network.
https://dl.google.com/android/repository/platform-tools-latest-windows.zip
adb connect 192.168.1.42:5555 (e.g.)
Check it is connected:
adb devices
adb shell pm list packages
Check available space
adb shell df /
adb push black_1920x1080.png /sdcard/black_1920x1080.png
adb shell am start -a android.intent.action.VIEW -d file:///sdcard/black_1920x1080.png -t image/png
adb shell rm /sdcard/black_1920x1080.png
adb shell find /storage/sda1 -iname "*.mp4"
adb shell ls -l /sdcard/
adb shell am start -a android.intent.action.VIEW -p com.hisilicon.android.videoplayer -d "file:///storage/sda1/Airplane.mp4" -t video/mp4
or:
adb shell am start -a android.intent.action.VIEW -n com.newlink.cast/tv.danmaku.ijk.media.example.activities.VideoActivity -d "file:///storage/sda1/Pirate.mp4" -t video/mp4
adb shell getevent -lp
adb shell input keyevent KEYCODE_MEDIA_NEXT
or by number:
adb shell input keyevent 87
List of events:
KEYCODE_HOME 3 Home KEYCODE_BACK 4 Back / exit KEYCODE_MENU 82 Menu / player options KEYCODE_SETTINGS 176 Settings KEYCODE_DPAD_UP 19 Up KEYCODE_DPAD_DOWN 20 Down KEYCODE_DPAD_LEFT 21 Left / rewind in some players KEYCODE_DPAD_RIGHT 22 Right / forward in some players KEYCODE_DPAD_CENTER 23 OK / select KEYCODE_ENTER 66 Enter / select KEYCODE_ESCAPE 111 Escape / back-like
KEYCODE_MEDIA_PLAY_PAUSE 85 Play/pause toggle KEYCODE_MEDIA_STOP 86 Stop KEYCODE_MEDIA_NEXT 87 Next item KEYCODE_MEDIA_PREVIOUS 88 Previous item KEYCODE_MEDIA_REWIND 89 Rewind KEYCODE_MEDIA_FAST_FORWARD 90 Fast-forward KEYCODE_MEDIA_PLAY 126 Play KEYCODE_MEDIA_PAUSE 127 Pause KEYCODE_MEDIA_CLOSE 128 Close media KEYCODE_MEDIA_EJECT 129 Eject KEYCODE_MEDIA_RECORD 130 Record KEYCODE_MEDIA_SKIP_FORWARD 272 Skip forward KEYCODE_MEDIA_SKIP_BACKWARD 273 Skip backward KEYCODE_MEDIA_STEP_FORWARD 274 Step forward KEYCODE_MEDIA_STEP_BACKWARD 275 Step backward
KEYCODE_POWER 26 Power toggle; you found this turns projector off KEYCODE_SLEEP 223 Sleep; did nothing on your firmware KEYCODE_WAKEUP 224 Wake; only works if ADB remains alive KEYCODE_TV_POWER 177 TV/projector power KEYCODE_TV_INPUT 178 Input/source KEYCODE_STB_POWER 179 Set-top-box power KEYCODE_STB_INPUT 180 Set-top-box input KEYCODE_AVR_POWER 181 AV receiver power KEYCODE_AVR_INPUT 182 AV receiver input KEYCODE_GUIDE 172 Guide KEYCODE_CAPTIONS 175 Captions/subtitles KEYCODE_INFO 165 Info / OSD KEYCODE_TV 170 TV KEYCODE_WINDOW 171 Window / PiP-like on some builds KEYCODE_CHANNEL_UP 166 Channel up / sometimes next KEYCODE_CHANNEL_DOWN 167 Channel down / sometimes previous KEYCODE_TV_MEDIA_CONTEXT_MENU 257 TV media menu
KEYCODE_VOLUME_UP 24 Volume up KEYCODE_VOLUME_DOWN 25 Volume down KEYCODE_VOLUME_MUTE 164 Mute KEYCODE_MUTE 91 Mute mic/audio route on some builds
KEYCODE_PROG_RED 183 KEYCODE_PROG_GREEN 184 KEYCODE_PROG_YELLOW 185 KEYCODE_PROG_BLUE 186
KEYCODE_0 7 KEYCODE_1 8 KEYCODE_2 9 KEYCODE_3 10 KEYCODE_4 11 KEYCODE_5 12 KEYCODE_6 13 KEYCODE_7 14 KEYCODE_8 15 KEYCODE_9 16 KEYCODE_STAR 17 KEYCODE_POUND 18
KEYCODE_APP_SWITCH 187 Recent apps KEYCODE_SEARCH 84 Search KEYCODE_ASSIST 219 Assistant KEYCODE_BRIGHTNESS_DOWN 220 Brightness down KEYCODE_BRIGHTNESS_UP 221 Brightness up KEYCODE_NOTIFICATION 83 Notification panel KEYCODE_SOFT_SLEEP 276 Soft sleep, if supported