Automatically Switch HDR/SDR Mode on LG TV (WebOS)

[Johnson145]

I've written a small shell script that automates syncing the hdr setting for LG tvs. It's meant to be running on the same machine as HyperHDR (not the TV itself, but e.g. a Raspberry Pi), fetches HDR information from the TV and updates HyperHDR accordingly. I.e. this does not require your TV to get rooted.

I think I haven't seen something similar on this repo yet, so maybe helpful for others:

Script

#!/bin/bash

# --- Configuration ---
#!! Change this to your TV's IP address!!
TV_IP="YOUR_LG_TV_IP"

# HyperHDR is on the same machine, so we use localhost.
HYPERHDR_IP="127.0.0.1"
POLL_INTERVAL=5 # Check every 5 seconds

# --- End of Configuration ---

LAST_STATE="unknown"

echo "[$(date)] Starting HyperHDR automation script..."

while true; do
    #echo "[$(date)] Polling picture mode from TV..."

    PIC_MODE_JSON=$(timeout 4 bscpylgtvcommand "$TV_IP" get_picture_settings '["pictureMode"]' true 2>&1)
    CMD_EXIT=$?

    if [ $CMD_EXIT -ne 0 ]; then
        echo "[$(date)] Failed to get picture settings (exit: $CMD_EXIT): $PIC_MODE_JSON"
        REQUIRED_STATE="sdr"
        PIC_MODE="unknown"
    else
        #echo "[$(date)] Raw picture settings: $PIC_MODE_JSON"

        PIC_MODE=$(echo "$PIC_MODE_JSON" | jq -r '.pictureMode | ascii_downcase' 2>/dev/null)
        if [[ $? -ne 0 || -z "$PIC_MODE" ]]; then
            echo "[$(date)] Error parsing picture mode. Defaulting to 'sdr'."
            REQUIRED_STATE="sdr"
            PIC_MODE="unknown"
        elif [[ "$PIC_MODE" == *"hdr"* || "$PIC_MODE" == *"dolby"* ]]; then
            REQUIRED_STATE="hdr"
        else
            REQUIRED_STATE="sdr"
        fi
    fi

    if [[ "$REQUIRED_STATE" != "$LAST_STATE" ]]; then
        echo "[$(date)] State change: $REQUIRED_STATE (Picture mode: $PIC_MODE)"
        if [[ "$REQUIRED_STATE" == "hdr" ]]; then
            curl -s -X POST "http://$HYPERHDR_IP:8090/json-rpc" -d '{"command":"videomodehdr","HDR":1}' -o /dev/null \
                && echo "[$(date)] HDR mode command sent." \
                || echo "[$(date)] Failed to send HDR command."
        else
            curl -s -X POST "http://$HYPERHDR_IP:8090/json-rpc" -d '{"command":"videomodehdr","HDR":0}' -o /dev/null \
                && echo "[$(date)] SDR mode command sent." \
                || echo "[$(date)] Failed to send SDR command."
        fi
        LAST_STATE=$REQUIRED_STATE
    fi

    sleep $POLL_INTERVAL
done

Tutorial

Details

Here is a complete, step-by-step guide to create a shell script that runs on your Raspberry Pi. This script will:

1. Poll your LG TV for its current picture mode.

2. Check if the mode indicates HDR or SDR.

3. Send the correct command to your local HyperHDR server only when the state changes.

4. Run persistently as a background service.

Part 1: Prerequisites & Setup on Your Raspberry Pi

First, you need to install the necessary tools on your Pi. Open an SSH terminal to your Raspberry Pi (the one running HyperHDR) and execute the following commands.

1. Update your package list:

sudo apt-get update

2. Install curl, jq (a JSON parser), and Python's package manager:

sudo apt-get install -y curl jq python3-pip

3. Install the LG TV control library:

pip3 install bscpylgtv --break-system-packages

(prefer to use virtual env instead)

4. One-Time TV Pairing:

bscpylgtvcommand YOUR_LG_TV_IP get_picture_settings "[\"pictureMode\"]" true

When you run this, your LG TV will display a pairing request. You must accept it on the TV. After you accept, the command will run successfully and show you the current picture mode. You only need to do this once.

Part 2: The Automation Shell Script

Now, let's create the script itself.

1. Create the script file:

vim /home/pi/hyperhdr_auto.sh

1. Paste the script content as given before into the editor. You must edit the TV_IP variable.

2. Make the script executable:

chmod +x /home/pi/hyperhdr_auto.sh

You can test it by running ./hyperhdr_auto.sh. You should see it poll and set the initial state. You can stop it with Ctrl+C.

Part 3: Running the Script as a Permanent Service

The final step is to make this script run automatically in the background and restart on boot. We'll use systemd for this.

1. Create a new service file:

sudo vim /etc/systemd/system/webos-hyperhdr-mode-automation.service

2. Paste the following content into the editor. This defines the service.

[Unit]
Description=HyperHDR HDR/SDR Automation Service for LG TV (WebOS)
After=network.target [email protected]
Requires[email protected]

[Service]
Type=simple
User=pi
WorkingDirectory=/home/pi
Environment="PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/local/games:/usr/games:/home/pi/.local/bin"
ExecStartPre=/bin/sleep 30
ExecStart=/home/pi/hyperhdr_auto.sh
Restart=on-failure
RestartSec=10

[Install]
WantedBy=multi-user.target

Note: If your Raspberry Pi username is not pi, change the User= and ExecStart= lines to match your user and home directory.

3. Save and Exit (Ctrl+O, Enter, Ctrl+X).

4. Enable and Start the Service:

   Now, tell systemd to recognize and run your new service.

# Reload the systemd daemon to find the new service
sudo systemctl daemon-reload

# Enable the service (so it starts on every boot)
sudo systemctl enable webos-hyperhdr-mode-automation.service

# Start the service right now
sudo systemctl start webos-hyperhdr-mode-automation.service

5. Check the Status:

   Your script is now running in the background. You can check its status or see its log output with these commands:

# Check if the service is active and running
systemctl status webos-hyperhdr-mode-automation.service

# View the live log output (press Ctrl+C to exit)
journalctl -fu webos-hyperhdr-mode-automation.service

LUT Calibration Conflict

When running the LUT calibration, you should temporarily disable this service. Otherwise it may cause incorrect calibration values.