Browser Compatibility

Browser detection, feature detection, and compatibility handling in lib-jitsi-meet

Browser Compatibility

lib-jitsi-meet uses the BrowserCapabilities class for browser detection and feature support checking, along with webrtc-adapter for polyfills.

BrowserCapabilities Class

Extends BrowserDetection from @jitsi/js-utils with lib-jitsi-meet-specific capabilities.

import BrowserDetection from '@jitsi/js-utils/browser-detection/BrowserDetection';

export default class BrowserCapabilities extends BrowserDetection {
    // lib-jitsi-meet specific methods
}

Source: modules/browser/BrowserCapabilities.ts:1, 22

Minimum Browser Versions

const MIN_REQUIRED_CHROME_VERSION = 72;
const MIN_REQUIRED_FIREFOX_VERSION = 91;
const MIN_REQUIRED_SAFARI_VERSION = 14;
const MIN_REQUIRED_IOS_VERSION = 14;

Source: modules/browser/BrowserCapabilities.ts:4-7

Version Detection

Safari Version

_getSafariVersion(): number {
    if (this.isSafari()) {
        return Number.parseInt(this.getVersion(), 10);
    }
    return -1;
}

Source: modules/browser/BrowserCapabilities.ts:41-47

iOS Version

_getIOSVersion(): number {
    if (this.isWebKitBased()) {
        return Number.parseInt(this.getOSVersion(), 10);
    }
    return -1;
}

Source: modules/browser/BrowserCapabilities.ts:28-34

Browser Support Checks

Overall Support

isSupported(): boolean {
    // Check for WebRTC APIs (some security extensions disable them)
    if (typeof RTCPeerConnection === 'undefined'
            || !navigator?.mediaDevices?.enumerateDevices 
            || !navigator?.mediaDevices?.getUserMedia) {
        return false;
    }
    
    if (this.isSafari() && this._getSafariVersion() < MIN_REQUIRED_SAFARI_VERSION) {
        return false;
    }
    
    return (this.isChromiumBased() && this.isEngineVersionGreaterThan(MIN_REQUIRED_CHROME_VERSION - 1))
        || (this.isFirefox() && this.isVersionGreaterThan(MIN_REQUIRED_FIREFOX_VERSION - 1))
        || this.isReactNative()
        || this.isWebKitBased();
}

Source: modules/browser/BrowserCapabilities.ts:101-116

Platform-Specific Support

Android

isSupportedAndroidBrowser(): boolean {
    return this.isChromiumBased() || this.isFirefox();
}

Source: modules/browser/BrowserCapabilities.ts:123-125

iOS

isSupportedIOSBrowser(): boolean {
    // After iPadOS 13, UA string conceals version and pretends to be macOS 10.15.7
    if (!this.isSafari() && this.isWebKitBased() && this.getOSVersion() === FROZEN_MACOS_VERSION) {
        return true;
    }
    
    return this._getSafariVersion() >= MIN_REQUIRED_IOS_VERSION
            || this._getIOSVersion() >= MIN_REQUIRED_IOS_VERSION;
}

The iPad detection workaround is necessary because iPadOS 13+ masquerades as macOS in the user agent.

Source: modules/browser/BrowserCapabilities.ts:10-11, 132-140

Mobile Detection

isMobileDevice(): boolean {
    return this.isAndroidBrowser() || this.isIosBrowser() || this.isReactNative();
}

isAndroidBrowser(): boolean {
    return !this.isReactNative() && this.getOS() === 'Android';
}

isIosBrowser(): boolean {
    return !this.isReactNative() && this.getOS() === 'iOS';
}

Source: modules/browser/BrowserCapabilities.ts:83-85, 65-67, 74-76

Trusted Web App Detection

isTwa(): boolean {
    return 'matchMedia' in window && window.matchMedia('(display-mode:standalone)').matches;
}

Detects if running as a Trusted Web App (Android).

Source: modules/browser/BrowserCapabilities.ts:92-94

Codec Support

setCodecPreferences API

supportsCodecPreferences(): boolean {
    return Boolean('setCodecPreferences' in window.RTCRtpTransceiver?.prototype
        && typeof window.RTCRtpReceiver?.getCapabilities !== 'undefined')
        
        // Safari bug: https://bugs.webkit.org/show_bug.cgi?id=215567
        && !this.isWebKitBased()
        
        // Firefox freeze bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1917800
        && !this.isFirefox();
}

Source: modules/browser/BrowserCapabilities.ts:178-189

Codec Selection API

supportsCodecSelectionAPI(): boolean {
    return this.isChromiumBased() && this.isEngineVersionGreaterThan(125);
}

Chrome 126+ supports changing codecs on encodings without renegotiation.

Source: modules/browser/BrowserCapabilities.ts:199-201

VP9 Support

supportsVP9(): boolean {
    // Disabled on Firefox (simulcast disabled by default)
    // Disabled on Safari (decoder/encoder issues)
    return !(this.isWebKitBased() || this.isFirefox());
}

See: https://bugs.webkit.org/show_bug.cgi?id=231074

Source: modules/browser/BrowserCapabilities.ts:276-281

SVC Support

supportsSVC(): boolean {
    return !this.isFirefox();
}

Scalable Video Coding is supported on all browsers except Firefox.

Source: modules/browser/BrowserCapabilities.ts:288-290

Simulcast

SDP Munging for Simulcast

usesSdpMungingForSimulcast(): boolean {
    return this.isChromiumBased() || this.isReactNative() || this.isWebKitBased();
}

Chrome, Safari, and React Native use SDP munging. Firefox uses RIDs/MIDs.

Source: modules/browser/BrowserCapabilities.ts:297-299

RIDs for Simulcast

usesRidsForSimulcast(): boolean {
    return false;  // Currently unused
}

Source: modules/browser/BrowserCapabilities.ts:307-309

Scalability Mode API

supportsScalabilityModeAPI(): boolean {
    return this.isChromiumBased() && this.isEngineVersionGreaterThan(112);
}

Chrome 113+ supports the Scalability Mode API for VP9/AV1 simulcast and full SVC.

Source: modules/browser/BrowserCapabilities.ts:255-257

E2EE Support

Insertable Streams

supportsInsertableStreams(): boolean {
    if (!window.RTCRtpSender?.prototype.createEncodedStreams) {
        return false;
    }
    
    // Feature-detect transferable streams (needed for worker)
    const stream = new ReadableStream();
    
    try {
        window.postMessage(stream, '*', [ stream ]);
        return true;
    } catch {
        return false;
    }
}

Source: modules/browser/BrowserCapabilities.ts:340-357

Encoded Transform

supportsEncodedTransform(): boolean {
    return Boolean(window.RTCRtpScriptTransform);
}

Alternative to insertable streams, currently Safari/WebKit behind a flag.

Source: modules/browser/BrowserCapabilities.ts:331-333

Audio RED Format

supportsAudioRed(): boolean {
    return Boolean(
        window.RTCRtpSender?.getCapabilities('audio')?.codecs
            .some(codec => codec.mimeType === 'audio/red')
        && window.RTCRtpReceiver?.getCapabilities('audio')?.codecs
            .some(codec => codec.mimeType === 'audio/red')
    );
}

Source: modules/browser/BrowserCapabilities.ts:364-367

Statistics Support

Bandwidth Statistics

supportsBandwidthStatistics(): boolean {
    // Not implemented for Firefox or Safari on lib-jitsi-meet side
    return !this.isFirefox() && !this.isWebKitBased();
}

Source: modules/browser/BrowserCapabilities.ts:167-171

RTT Statistics

supportsRTTStatistics(): boolean {
    // Firefox doesn't report RTT for ICE candidate pairs
    // See: https://bugzilla.mozilla.org/show_bug.cgi?id=1241066
    return !this.isFirefox();
}

Source: modules/browser/BrowserCapabilities.ts:236-246

Receiver Stats

supportsReceiverStats(): boolean {
    return typeof window.RTCRtpReceiver !== 'undefined'
        && Object.keys(RTCRtpReceiver.prototype).indexOf('getSynchronizationSources') > -1;
}

Source: modules/browser/BrowserCapabilities.ts:226-229

Track-Based Stats

supportsTrackBasedStats(): boolean {
    return this.isChromiumBased() && this.isEngineVersionLessThan(112);
}

Older Chrome versions (< 112) support track-based statistics for resolution/framerate.

Source: modules/browser/BrowserCapabilities.ts:265-267

Media Capabilities

getDisplayMedia Support

supportsGetDisplayMedia(): boolean {
    return typeof navigator.getDisplayMedia !== 'undefined'
        || (typeof navigator.mediaDevices?.getDisplayMedia !== 'undefined');
}

Source: modules/browser/BrowserCapabilities.ts:316-320

Device Change Events

supportsDeviceChangeEvent(): boolean {
    return typeof navigator.mediaDevices?.ondevicechange !== 'undefined'
        && typeof navigator.mediaDevices?.addEventListener !== 'undefined';
}

Source: modules/browser/BrowserCapabilities.ts:216-219

Video Mute Strategy

doesVideoMuteByStreamRemove(): boolean {
    return this.isChromiumBased() || this.isWebKitBased() || this.isFirefox();
}

On Firefox, the MediaStream is removed from PeerConnection on mute to turn off camera. See: https://bugzilla.mozilla.org/show_bug.cgi?id=1735951

Source: modules/browser/BrowserCapabilities.ts:56-58

Video Mute Events

supportsVideoMuteOnConnInterrupted(): any | boolean {
    return this.isChromiumBased() || this.isReactNative();
}

Chrome and React Native fire ‘onmute’/‘onunmute’ events when connection is interrupted.

Source: modules/browser/BrowserCapabilities.ts:158-160

Browser-Specific Features

User Interaction for Unmute

isUserInteractionRequiredForUnmute(): boolean {
    return this.isFirefox() && this.isVersionLessThan(68);
}

Older Firefox versions require user interaction before unmute.

Source: modules/browser/BrowserCapabilities.ts:148-150

RTX Support

supportsRTX(): boolean {
    // Disable RTX on Firefox < 96 (prefer simulcast)
    // See: https://bugzilla.mozilla.org/show_bug.cgi?id=1738504
    return !(this.isFirefox() && this.isVersionLessThan(96));
}

Source: modules/browser/BrowserCapabilities.ts:383-387

Dependency Descriptor Headers

supportsDDExtHeaders(): boolean {
    return !(this.isFirefox() && this.isVersionLessThan(136));
}

Firefox 136+ supports Dependency Descriptor RTP header extension.

Source: modules/browser/BrowserCapabilities.ts:208-210

Voice Activity Detection

supportsVADDetection(): boolean {
    return this.isChromiumBased();
}

VADAudioAnalyser service is only supported on Chromium-based browsers.

Source: modules/browser/BrowserCapabilities.ts:374-376

webrtc-adapter Integration

lib-jitsi-meet uses webrtc-adapter for WebRTC API polyfills:

import 'webrtc-adapter';

This provides:

• Unified WebRTC API across browsers
• getUserMedia polyfill
• RTCPeerConnection shims
• Browser compatibility fixes

Source: modules/RTC/RTCUtils.js:3, CLAUDE.md:53

Usage Pattern

import browser from '../browser';

// Check feature support
if (browser.supportsCodecPreferences()) {
    // Use setCodecPreferences API
    transceiver.setCodecPreferences(capabilities);
} else {
    // Fallback to SDP munging
    mungedSdp = mungeCodecOrder(sdp);
}

// Platform-specific logic
if (browser.isMobileDevice()) {
    // Use mobile-optimized settings
    codecOrder = MOBILE_VIDEO_CODEC_ORDER;
} else {
    codecOrder = DESKTOP_VIDEO_CODEC_ORDER;
}

// Browser-specific workarounds
if (browser.isWebKitBased()) {
    // Safari bug workaround
    constraints.video.height = { ideal: height };
    constraints.video.width = { ideal: width };
}

Common Compatibility Checks

Before Using APIs

// Codec selection
if (browser.supportsCodecPreferences() && !browser.isWebKitBased()) {
    // Chrome/Edge only
}

if (browser.supportsCodecSelectionAPI()) {
    // Chrome 126+ only
}

// E2EE
if (browser.supportsInsertableStreams() || browser.supportsEncodedTransform()) {
    // Enable E2EE
}

// Screen sharing
if (browser.supportsGetDisplayMedia()) {
    // Use getDisplayMedia
} else {
    // Fallback to extension or error
}

// Statistics
if (browser.supportsReceiverStats()) {
    receiver.getSynchronizationSources();
}

Platform Detection

if (browser.isMobileDevice()) {
    if (browser.isAndroidBrowser()) {
        // Android-specific
        if (browser.isSupportedAndroidBrowser()) {
            // Chrome or Firefox on Android
        }
    } else if (browser.isIosBrowser()) {
        // iOS-specific
        if (browser.isSupportedIOSBrowser()) {
            // iOS 14+ Safari or WKWebView
        }
    }
}

iPad Detection Issue

Starting with iPadOS 13, Safari pretends to be macOS 10.15.7 in the user agent:

const FROZEN_MACOS_VERSION = '10.15.7';

if (!this.isSafari() && this.isWebKitBased() 
    && this.getOSVersion() === FROZEN_MACOS_VERSION) {
    // Likely an iPad
    return true;
}

This workaround is necessary for proper iPad detection.

Source: modules/browser/BrowserCapabilities.ts:10-11, 134-136

Best Practices

1. Always check feature support: Don’t assume APIs exist

   if (browser.supportsCodecPreferences()) {
       // Use API
   }
   

2. Use platform detection for optimization: Different defaults for mobile

   const codecOrder = browser.isMobileDevice() 
       ? MOBILE_VIDEO_CODEC_ORDER 
       : DESKTOP_VIDEO_CODEC_ORDER;
   

3. Handle browser bugs: Apply workarounds where necessary

   if (browser.isWebKitBased()) {
       // Safari-specific workaround
   }
   

4. Graceful degradation: Provide fallbacks for unsupported features

   if (!browser.supportsGetDisplayMedia()) {
       // Show extension installation prompt or disable screenshare
   }
   

5. Check minimum versions: Block unsupported browsers early

   if (!browser.isSupported()) {
       // Show unsupported browser message
   }
   

Next Steps

• WebRTC Internals - Browser-specific WebRTC handling
• Codec Selection - Codec support by browser
• Network Optimization - Connection handling