CastSponsorSkip

A Go program that skips sponsored YouTube content and skippable ads on all local Google Cast devices, using the SponsorBlock API. This project was inspired by sponsorblockcast, but written from scratch to decrease memory and CPU usage, and to work around some of its problems (see Differences from sponsorblockcast).

When run, this program will watch all Google Cast devices on the LAN. If a Cast device begins playing a YouTube video, sponsored segments are fetched from the SponsorBlock API. When the device reaches a sponsored segment, the CastSponsorSkip will quickly seek to the end of the segment.

Additionally, CastSponsorSkip will look for skippable YouTube ads, and automatically hit the skip button when it becomes available.

Installation

Docker

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You can install Docker directly or use Docker Compose (Or use Podman, Portainer, etc). Please note you MUST use the host network as shown below for cli or in the example docker-compose file.

Docker

Run the below commands as root or a member of the docker group:

docker run --network=host --name=castsponsorskip ghcr.io/gabe565/castsponsorskip

Docker Compose

First you will need a docker-compose.yaml file, such as the one included in this repo. Run the below commands as root or a member of the docker group:

docker compose up -d

Home Assistant Addon

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A Home Assistant addon is provided by @alexbelgium and @bruvv. See alexbelgium/hassio-addons for installation instructions.

APT (Ubuntu, Debian)

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1. If you don't have it already, install the ca-certificates package

   sudo apt install ca-certificates

2. Add gabe565 apt repository

   echo 'deb [trusted=yes] https://apt.gabe565.com /' | sudo tee /etc/apt/sources.list.d/gabe565.list
   

3. Update apt repositories

   sudo apt update

4. Install CastSponsorSkip

   sudo apt install castsponsorskip

RPM (CentOS, RHEL)

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1. If you don't have it already, install the ca-certificates package

   sudo dnf install ca-certificates

2. Add gabe565 rpm repository to /etc/yum.repos.d/gabe565.repo

   [gabe565]
   name=gabe565
   baseurl=https://rpm.gabe565.com
   enabled=1
   gpgcheck=0

3. Install CastSponsorSkip

   sudo dnf install castsponsorskip

AUR (Arch Linux)

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Install castsponsorskip-bin with your AUR helper of choice.

Homebrew (macOS, Linux)

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Install CastSponsorSkip from gabe565/homebrew-tap:

brew install gabe565/tap/castsponsorskip

Kubernetes

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CastSponsorSkip doesn't require a Service or Ingress, so it's simple to host in Kubernetes with a single Deployment. The only gotcha is that hostNetwork must be enabled for device discovery to work.

A Helm chart is available to make Kubernetes deployment even simpler. For more information, see charts.gabe565.com or Artifact Hub.

Manual Installation

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Download and run the latest release binary for your system and architecture.

Usage

Run castsponsorskip from a terminal or activate the service with systemd:

systemctl enable --now castsponsorskip

Homebrew Instructions

Use brew services to start CastSponsorSkip:

brew services start castsponsorskip

Configuration

CastSponsorSkip can be configured with envs, command-line flags, or a config file. Some notable envs are listed below, but all flags can be set with envs.
To use an env that is not listed here, capitalize all characters, replace - with _, and prefix with CSS_. For example, --paused-interval=1m would become CSS_PAUSED_INTERVAL=1m.

Notable Envs

Here's a list of commonly used envs. Also see full env reference.

Env	Description	Default
CSS_DISCOVER_INTERVAL	Interval to restart the DNS discovery client.	5m
CSS_PAUSED_INTERVAL	Time to wait between each poll of the Cast device status when paused.	1m
CSS_PLAYING_INTERVAL	Time to wait between each poll of the Cast device status when playing.	500ms
CSS_CATEGORIES	Comma-separated list of SponsorBlock categories to skip, see category list and category breakdown.	sponsor
CSS_YOUTUBE_API_KEY	YouTube API key for fallback video identification (required on some Chromecast devices).
CSS_MUTE_ADS	Mutes the device while an ad is playing.	true
CSS_DEVICES	Comma-separated list of device addresses. This will disable discovery and is not recommended unless discovery fails.	[]
CSS_SKIP_SPONSORS	Toggles sponsored segment skipping via the SponsorBlock API. If disabled, only YouTube ads will be skipped.	true

Note

sponsorblockcast envs are also supported to simplify the migration to CastSponsorSkip. When used, a deprecation warning will be logged with an updated env key and value. There are currently no plans to remove these envs.

Flags

See command-line reference.

Systemd

To modify the variables when running as a systemd service, create an override for the service with:

sudo systemctl edit castsponsorskip.service

This will open a blank override file where you can specify environment variables like so:

[Service]
Environment="CSS_PAUSED_INTERVAL=1m"
Environment="CSS_PLAYING_INTERVAL=1s"
Environment="CSS_CATEGORIES=sponsor,selfpromo"

To modify the variables when running as a Docker container, you can add arguments to the docker run command like so:

docker run --network=host --env CSS_PAUSED_INTERVAL=5m --env CSS_PLAYING_INTERVAL=2s --name=castsponsorskip ghcr.io/gabe565/castsponsorskip

Docker Compose

When using docker-compose.yaml, you can simply edit the environment directive as shown in the example file.

Differences from sponsorblockcast

• Uses the SponsorBlock enhanced privacy endpoint. When searching for sponsored segments, the video ID is hashed and only the first 4 characters of the hash are passed to SponsorBlock. This allows CastSponsorSkip to fetch segments without telling SponsorBlock what video is being watched.
• Compiles to a single binary. No dependencies are required other than CastSponsorSkip.
• Scans Cast device status much less frequently when a YouTube video is not playing, resulting in decreased CPU usage and less stress on the Cast device.
• Written Go, which is the same language as go-chromecast. This means go-chromecast functions can be called directly instead of relying on shell scripts, child commands, or string parsing.
• go-chromecast only needs to be loaded once within a single Go program, resulting in lower memory usage.
• Dependency updates are automated with Renovate.

I own 12 Google Cast devices, and have compared CPU and memory usage of the two programs. Note that CPU usage is measured in "milliCPU", meaning that 1m is equal to 1/1000 of a CPU. Here are the averages:

Program	CPU	Memory
sponsorblockcast	75m	70Mi
castsponsorskip	1m	10Mi