Why Twitch Mutes VOD Audio, and What -unmuted Means

What a muted passage really is

Twitch runs automated copyright detection on the audio of recorded broadcasts. When a passage matches a protected track, the audio of that range is removed from the recording. The video is untouched, the timeline keeps the same length, and playback continues normally — only the sound is gone.

This is decided on Twitch’s side, before any third-party player sees the file. A browser extension, a desktop app and NoSub all receive exactly the same muted recording.

The counterintuitive part: -unmuted marks the muted range

A Twitch VOD is served as an HLS playlist listing thousands of short segments. Inside a muted range, those segments are not named -muted as you would expect. They are listed with a -unmuted suffix.

In the public playlists handled by NoSub, requesting one of those -unmuted files returns HTTP 403 while the same path carrying -muted is served. The practical rule is therefore based on the CDN response: -unmuted does not mean that audible sound is available to the player.

What NoSub observes in public playlists

While implementing playback for muted passages, NoSub repeatedly encountered the same public-playlist behaviour:

• A -unmuted URI in the affected media playlists marks a passage that the public replay serves without its original audio.
• Requesting that -unmuted file directly returns 403, not the original sound.
• The matching -muted file is the only variant the CDN will serve.
• The timeline never changes length; only the audio of the range is missing.

What this means if you build a player

A player that forwards the playlist unchanged fails in a way that looks unrelated to audio:

• The 403 responses start exactly where the muted passage starts, so playback stalls mid-VOD instead of reporting a sound problem.
• The usual symptom is an endless loading spinner, which sends people hunting for a network or quality bug that does not exist.
• The fix is to rewrite -unmuted to -muted in the media playlist before handing it to the player.
• Separately, Twitch VOD CDNs send no CORS headers, so a browser player also needs the segments proxied to read their bytes.

Can the original audio be recovered?

Not from the public VOD source used by NoSub. Rewriting the segment name restores nothing — it only asks for the muted file that the CDN actually serves.

Recovering audible sound would require a separate copy saved before Twitch applied the muting. NoSub does not host or archive broadcasts, so it cannot supply such a copy.