Stop hls.js from flapping between quality levels on cellular (with abrSwitchInterval)

TL;DR ABR "flapping" is when your player hops between quality levels every few seconds on a jittery network, and each hop is a visible lurch. We'll detect it from LEVEL_SWITCHED events, then fix it in layers: widen the bandwidth-estimator memory, make upswitches earn their place, and cap the switch rate with abrSwitchInterval (new in hls.js 1.7). Config + a detection snippet you can paste in today. 📦 Code: github.com/USER/hlsjs-abr-tuning, replace before publishing The bug nobody reports correctly Users don't file "my ABR is flapping." They say the video "kept changing" or "couldn't decide." What's happening: on cellular, throughput is spiky, and the player's bandwidth estimator treats every spike as the new truth. One fast segment and it jumps to 1080p, one slow segment and it drops to 240p, over and over. Low rebuffer ratio, good startup time, and still a miserable watch. Counterintuitively, feeding the player fresher bandwidth data makes this worse, because fresher data is noisier. The fix is a player with a longer memory and slower reflexes. Let's build that. 1. First, detect the flap 📊 Don't tune by vibes. Count level switches per minute of playback. Every switch fires Hls.Events.LEVEL_SWITCHED . // abr-monitor.js, hls.js 1.7.x, node 20+ tooling / any modern browser import Hls from " hls.js " ; export function attachFlapMonitor ( hls ) { const switches = []; hls . on ( Hls . Events . LEVEL_SWITCHED , ( _evt , data ) => { const now = performance . now (); switches . push ({ t : now , level : data . level }); // keep a 60s sliding window while ( switches . length && now - switches [ 0 ]. t > 60 _000 ) switches . shift (); const perMin = switches . length ; const reversals = countReversals ( switches ); if ( perMin >= 6 ) { console . warn ( `[abr] flapping: ${ perMin } switches/min, ${ reversals } reversals` ); } }); } // a "reversal" = up then down (or down then up), the signature of flapping function countReversals ( s ) { let r = 0 ; for ( let i = 2 ; i < s . l