CapoWhy most audio extensions do nothing on Spotify or Tidal
Protected streaming audio will not give its decoded samples to page scripts. Any extension that works by attaching an analyser to the media element therefore produces silence on Spotify, Tidal, Apple Music, Amazon Music and Deezer. Processing the audio in place, inside the context that negotiated the encryption, is the way around it.
- The usual approach taps the media element. Protected media refuses.
- Capo instead splices its worklet into the audio graph itself.
- The samples never leave the context, so playback keeps working.
If you have tried a pitch or equalizer extension on a paid streaming service, you have probably watched it do nothing at all. The controls move, the audio does not change, and there is rarely any explanation. The reason is the same in every case, and it is not a bug.
What protected playback refuses to do
Streaming services deliver encrypted audio through the browser’s Encrypted Media Extensions. The decryption happens somewhere the page cannot see, and the browser will not hand the decoded samples back to ordinary JavaScript. That is the entire point: if page scripts could read the samples, the protection would be meaningless.
The standard way to process a page’s audio is to attach an analyser or a processing node to the media element. On protected media the browser refuses, and what comes out is silence or nothing at all. Every extension built that way stops at the same wall.
Processing in place instead of extracting
Capo takes a different route. Rather than pulling audio out of the page, it replaces the audio context so that every context — the page’s own included — carries a proxy destination, with the pitch-shifting worklet spliced between that proxy and the real output.
The consequence is the one that matters: the samples never leave the context that negotiated the encryption. Nothing is decrypted by Capo, nothing is copied, and nothing is exposed to any other script. The audio is processed on its way to the speakers and then it is gone.
Which services this covers
| Service | Where |
|---|---|
| Spotify | open.spotify.com, web player only |
| Apple Music | music.apple.com, web player only |
| Tidal | tidal.com and listen.tidal.com |
| Amazon Music | music.amazon.* regional storefronts |
| Deezer | deezer.com |
The desktop applications for these services are native software. No browser extension can reach them, and that limitation is not something a different approach would solve.
Pitch and speed, even on protected players.
Free · nothing uploadedWhat this does not settle
It does not mean every protected player behaves identically. Services change their web clients, and a layout change can break track detection without breaking audio processing. It also does not cover pages that never produce sound in the first place, where there is nothing to process at all.
Questions
Can a browser extension change the pitch of DRM-protected audio?
Why does my equalizer extension do nothing on Spotify?
Does Capo decrypt anything?
Does this work in the Spotify or Apple Music desktop apps?
Is processing protected audio the same as downloading it?
Keep reading
How to change the pitch or key of a song on Apple Music
The web player has no key control, and its audio is encrypted. Capo shifts it anyway, without downloading anything.
Why Capo ships three time-stretch engines instead of one
Audio quality picks between SoundTouch, Signalsmith and Rubber Band. What each one costs you, and when to change it.
Every site Capo works on, and the handful it cannot
Anything with HTML5 audio or video, plus per-site track detection on ten services. And the real limits.