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.

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

docker compose up -d

brew install gabe565/tap/castsponsorskip

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

systemctl enable --now castsponsorskip

brew services start castsponsorskip

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.

See command-line flag documentation here.

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

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

• 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: