simpson-tv

This project transforms your Raspberry Pi into a dedicated video playback device, ideal for display installations like a DIY Simpsons TV. It features two primary components: video_player and button_handler. These components interact to create a user-friendly media player with simple physical button-based controls. This project is inspired by Simpsons TV

`encode.py`

The encode.py script is a utility designed to encode video files into a format optimized for efficient playback on the Raspberry Pi. It utilizes the ffmpeg tool to transcode videos into a format compatible with the hardware acceleration capabilities of the Raspberry Pi's GPU.

Functionality

Video Detection: The script identifies video files within a specified directory by checking file extensions (e.g., .mp4, .mkv, .mov, .avi).
Video Encoding: For each detected video file, the script transcodes it into the MP4 format using the H.264 codec. This format is preferred for its compatibility with hardware-accelerated decoding on the Raspberry Pi.
Optimization Parameters: The encoding parameters are chosen to balance file size and playback quality. These parameters include:
- Resolution: Resized to 320x240 pixels, optimized for a 2.8-inch screen.
- Codec: H.264 (libx264) with the baseline profile and level 3.0.
- Encoding Speed: Medium preset, balancing speed and file size.
- Compression: Constant Rate Factor (CRF) of 26 for moderately high compression.
- Pixel Format: YUV420P for compatibility with hardware decoding.
Concurrency: The script uses a thread pool to parallelize the encoding process, improving efficiency by leveraging multiple CPU cores.

Encoded video files will be saved in a subdirectory named encoded within the specified directory.

`video_player`

Description

The video_player is a custom C program designed to efficiently manage and play a list of video files on the Raspberry Pi. It uses omxplayer, a command-line media player optimized for the Raspberry Pi's GPU, ensuring smooth video playback even on less powerful models like the Raspberry Pi Zero.

Features

Hardware Accelerated Playback: Utilizes the GPU for decoding video, which minimizes CPU usage and ensures smooth playback.
Automatic Video Looping: Automatically loops through a playlist of videos stored in a specified directory.
Shuffle Playback: Randomizes the order of videos to provide a varied viewing experience each cycle.
Signal Handling: Listens for signals to pause/resume playback and skip to the next video, allowing external control through physical buttons or other means.

Usage

The video_player is executed at startup and continuously loops through all MP4 files located in a specified directory. It can be controlled externally via UNIX signals to pause/resume and change videos.

`button_handler`

Description

The button_handler is a C program designed to interface with physical buttons connected to the GPIO pins of the Raspberry Pi. It provides physical controls for the video playback managed by video_player, enhancing user interaction without the need for a graphical interface.

Features

Multi-Function Button Input: Differentiates between single, double, and long button presses to provide multiple controls:
- Single Press: Pauses or resumes the video playback.
- Double Press: Skips to the next video in the playlist.
- Long Press: Can be configured to perform actions like shutting down the Raspberry Pi or resetting the playlist.
Debounce Logic: Implements software debouncing to ensure reliable button press detection.
Signal Emission: Sends specific UNIX signals to video_player based on button inputs to control video playback.

Usage

The button_handler monitors configured GPIO pins for button presses and sends commands to video_player based on user interactions. It must be started at boot to listen for button presses continuously.

Optimizing boot time

1. Use Raspberry Pi OS Lite

The Lite version of Raspberry Pi OS, doesn't include many of the desktop environment components, making it inherently faster to boot up than the full version. You've likely already chosen this, but it's important to reinforce its benefit for boot time optimization.

2. Disable Unnecessary Services

Raspberry Pi OS starts several services at boot that may not be necessary. Disabling these can speed up booting:

Disable HDMI if your project doesn't require video output to a monitor:
```
/usr/bin/tvservice -o
```
Add the above line to /etc/rc.local before exit 0 to disable HDMI output at boot.

3. Optimize `/boot/config.txt`

Adjust settings in /boot/config.txt to skip some checks and speed up the boot process:

Disable the Rainbow Screen: Add disable_splash=1.
Reduce boot delay: Set boot_delay=0 to skip the delay before boot code execution.

4. Limit Kernel and Service Logging

Verbose logging can slow down the boot process:

Configure rsyslog or systemd-journald to limit what is logged.
Edit /boot/cmdline.txt and adjust the console= settings to reduce the amount of logging to the console during boot.

5. Asynchronous Service Starting

Make sure services start asynchronously to avoid waiting for one to finish before starting another. This is generally handled by systemd but check that dependencies are managed correctly so that non-critical services do not block the boot sequence.

6. Profile the Boot Process

Use systemd-analyze to find out what's taking up the most time during boot:

systemd-analyze
systemd-analyze blame
systemd-analyze critical-chain

This tool shows you a breakdown of how long each service takes to start. Focus on optimizing or disabling the slowest services.

Steps to Configure a Read-Only Filesystem

1. Backup Your Data

Before making any changes, ensure you have a backup of your SD card or important data.

2. Prepare Your Raspberry Pi

Update your system to ensure all packages are up to date:
```
sudo apt-get update
sudo apt-get upgrade
```

3. Minimize Writing to the Disk

Move log files to a temporary filesystem (tmpfs):

sudo nano /etc/fstab

Add these lines:

tmpfs        /tmp            tmpfs   defaults,noatime,nosuid,size=100m        0       0
tmpfs        /var/log        tmpfs   nosuid,nodev                             0       0
tmpfs        /var/tmp        tmpfs   nosuid,nodev                             0       0

Save and close the file.

4. Adjust Boot Configuration

Edit the cmdline.txt to mount the root filesystem as read-only:
```
sudo nano /boot/cmdline.txt
```
Find the root entry and modify it from root=/dev/mmcblk0p2 to:
```
root=/dev/mmcblk0p2 ro
```
Additionally, add fastboot noswap ro at the end of the line.

5. Make System Changes for Read-Only Compatibility

Make DHCP client changes:

sudo rm /etc/systemd/system/dhcpcd5
sudo ln -s /lib/systemd/system/dhcpcd.service /etc/systemd/system/dhcpcd.service.dhcpcd5

Edit dhcpcd configuration to use a static IP or ensure it doesn't need to write:
```
sudo nano /etc/dhcpcd.conf
```
This is optional and depends on whether you are using a static IP.

Adjust systemd to handle read-only root:

sudo systemctl mask systemd-random-seed.service
sudo ln -s /dev/null /etc/tmpfiles.d/dhcpcd.conf
sudo ln -s /dev/null /etc/systemd/system/sysinit.target.wants/systemd-random-seed.service

6. Remount Root Filesystem as Read-Write When Needed

To make changes after this setup, you'll need to remount the filesystem as read-write:

sudo mount -o remount,rw /

When done, remount it as read-only:

sudo mount -o remount,ro /

Check if everything boots up correctly and your applications function as expected in a read-only environment.

Disable Networking and Bluetooth on Raspberry Pi

1. Disable Networking

To completely disable networking on your Raspberry Pi, you can unload and blacklist the kernel modules responsible for network interfaces. Here's how to do it:

Open the cmdline.txt file to add networking disable commands:
```
sudo nano /boot/cmdline.txt
```
Add ip=off to the end of the line to disable DHCP and networking services.
Blacklist Network Kernel Modules: Create a new blacklist file in the /etc/modprobe.d/ directory:
```
sudo nano /etc/modprobe.d/raspi-blacklist.conf
```
Add the following lines to disable Ethernet and Wi-Fi modules:
```
blacklist brcmfmac
blacklist brcmutil
blacklist smsc95xx
blacklist lan78xx
```
This disables the drivers for the onboard WiFi and Ethernet (depending on your model of Raspberry Pi).

2. Disable Bluetooth

To disable Bluetooth, you need to blacklist its kernel modules and disable its system services.

Add to the Blacklist File: Open the previously created blacklist file:
```
sudo nano /etc/modprobe.d/raspi-blacklist.conf
```
Add the following lines:
```
blacklist btbcm
blacklist hci_uart
```

Disable Related Services: Stop and disable Bluetooth services:

sudo systemctl disable bluetooth.service
sudo systemctl disable hciuart.service

3. Edit the config.txt File

Disable the hardware interfaces directly from the bootloader configuration:

Edit config.txt:
```
sudo nano /boot/config.txt
```
Add these lines to the end of the file:
```
dtoverlay=disable-wifi
dtoverlay=disable-bt
```
This will completely disable the onboard WiFi and Bluetooth hardware interfaces.

4. Optimize Boot Configurations

Ensure that no unnecessary services are started at boot:

Modify systemd services to prevent networking services from starting:

sudo systemctl disable dhcpcd.service
sudo systemctl mask networking.service

5. Reboot

After making these changes, reboot your Raspberry Pi to ensure all changes take effect and the modules are not loaded:

sudo reboot

Testing and Validation

After rebooting, check that the network interfaces are indeed disabled:
```
ifconfig -a
```
This command should not show any active network interfaces except for lo (local loopback).
Check Bluetooth status:
```
hciconfig
```
There should be no Bluetooth devices listed.

Installation of Systemd Services

To use these systemd service files:

Place the service files in /etc/systemd/system/ directory.
```
sudo nano /etc/systemd/system/tvplayer.service
sudo nano /etc/systemd/system/tvbutton.service
```
Copy and paste the content for each service file respectively and save them.
Reload the systemd manager configuration to recognize changes to service files.
```
sudo systemctl daemon-reload
```

Enable the services to start at boot.

sudo systemctl enable tvplayer.service
sudo systemctl enable tvbutton.service

Start the services.

sudo systemctl start tvplayer.service
sudo systemctl start tvbutton.service

Check the status of the services to ensure they are running correctly.

sudo systemctl status tvplayer.service
sudo systemctl status tvbutton.service

skywalker212/simpson-tv

simpson-tv

encode.py

Functionality

video_player

Description

Features

Usage

button_handler

Description

Features

Usage

Optimizing boot time

1. Use Raspberry Pi OS Lite

2. Disable Unnecessary Services

3. Optimize /boot/config.txt

4. Limit Kernel and Service Logging

5. Asynchronous Service Starting

6. Profile the Boot Process

Steps to Configure a Read-Only Filesystem

1. Backup Your Data

2. Prepare Your Raspberry Pi

3. Minimize Writing to the Disk

4. Adjust Boot Configuration

5. Make System Changes for Read-Only Compatibility

6. Remount Root Filesystem as Read-Write When Needed

Disable Networking and Bluetooth on Raspberry Pi

1. Disable Networking

2. Disable Bluetooth

3. Edit the config.txt File

4. Optimize Boot Configurations

5. Reboot

Testing and Validation

Installation of Systemd Services

`encode.py`

`video_player`

`button_handler`

3. Optimize `/boot/config.txt`