MBs Tab Volume Control od monerobull

Tab Volume Control

A lightweight Firefox extension to set the audio volume of individual websites. Volumes are remembered per site (by hostname) and re-applied automatically on future visits.

Features

• Per-site volume control from 0–100%, saved automatically
• Mute / unmute with one click (restores your previous level)
• Works with both plain <audio>/<video> elements and sites that use the Web Audio API
• Acts as a multiplier on top of the site's own volume control, so a site's
  built-in slider (e.g. YouTube's) keeps working alongside it
• Embedded cross-origin players (e.g. iframes) inherit the parent page's setting
• Visual indicator for tabs that are currently producing audio
• Leaves a site's audio untouched until you actually set a volume for it

Usage

Click the toolbar icon to open the popup. It lists the open tabs in the current
window that support volume control. Drag a slider to set that site's volume, or
click the speaker icon to mute/unmute. Changes apply immediately to every open
tab of the same site and are remembered for next time.

How it works

• A content script injects a small page-context script (content_scripts/inject.js)
  that hooks HTMLMediaElement and the Web Audio API. It intercepts the
  element's volume property so the chosen level is applied as a multiplier
  (output = siteVolume × extensionVolume), letting a site's own volume control
  keep functioning, and uses a Web Audio gain node for sites that route audio
  through the Web Audio API.
• A background script (background.js) resolves the requesting frame's
  top-level host, so cross-origin iframes get the volume set for the page
  they're embedded in.
• Settings are stored with browser.storage.local, keyed by hostname.

Permissions

• tabs — list open tabs and their titles/favicons in the popup
• storage — remember per-site volume settings
• <all_urls> — apply volume on any site you visit