fix: player UX, ad fingerprinting, Android TV 9 white screen

Address issues #217 #218 and integrate the useful parts of PR #219 without
regressions: stop player rebuild on episode reverse, grid/paged episodes,
poster placeholders, chrome69 client transpile for Amlogic WebView, and
duration-signature ad block detection while keeping interstitial/proxy filters.

Bump to 4.9.15.

lib/utils/m3u8-ad-detector.ts

@@ -211,15 +211,72 @@ export function learnMainPattern(blocks: Block[]): MainPattern {
     return { filenameRegex, avgDuration, commonPrefix, pathPrefix };
 }
 
+/**
+ * Find blocks that share an identical sequence of segment durations (fingerprint)
+ * with another block in the playlist.
+ *
+ * If a block (with >= 3 segments) has an identical duration signature
+ * as another block in the playlist, and it is not the main content block,
+ * it is extremely likely to be a repeated inserted ad block.
+ */
+export function findDuplicateSignatureBlockIndices(blocks: Block[]): Set<number> {
+    const duplicateIndices = new Set<number>();
+    if (!blocks || blocks.length < 2) return duplicateIndices;
+
+    // Find the largest block (assumed main content block)
+    let mainBlockIndex = -1;
+    let maxSegments = 0;
+    blocks.forEach((block, idx) => {
+        if (block.segments.length > maxSegments) {
+            maxSegments = block.segments.length;
+            mainBlockIndex = idx;
+        }
+    });
+
+    // Map signature -> array of block indices
+    const signatureMap = new Map<string, number[]>();
+
+    blocks.forEach((block, idx) => {
+        // Require at least 3 segments to form a signature to prevent accidental single-segment collisions
+        if (block.segments.length < 3) return;
+
+        // Signature based on segment durations rounded to 3 decimal places (milliseconds precision)
+        const signature = block.segments.map(s => s.duration.toFixed(3)).join(',');
+
+        const existing = signatureMap.get(signature) || [];
+        existing.push(idx);
+        signatureMap.set(signature, existing);
+    });
+
+    // Flag blocks whose signatures appear 2 or more times
+    signatureMap.forEach((indices) => {
+        if (indices.length >= 2) {
+            indices.forEach(idx => {
+                // Ensure we don't accidentally flag the main content block
+                if (idx !== mainBlockIndex && blocks[idx].segments.length < maxSegments * 0.8) {
+                    duplicateIndices.add(idx);
+                }
+            });
+        }
+    });
+
+    return duplicateIndices;
+}
+
 /**
  * Score a block for ad likelihood based on heuristics
  * Returns a score where higher = more likely to be an ad
  */
-export function scoreBlock(block: Block, mainPattern: MainPattern, extraKeywords: string[] = []): number {
+export function scoreBlock(
+    block: Block,
+    mainPattern: MainPattern,
+    extraKeywords: string[] = [],
+    isDuplicateSignature: boolean = false
+): number {
     let score = 0;
 
-    // If block has CUE tag, it's definitely an ad
-    if (block.hasCueTag) {
+    // If block has CUE tag or matches a duplicate signature, it's definitely an ad
+    if (block.hasCueTag || isDuplicateSignature) {
         return 10; // Max score
     }
 

lib/utils/m3u8-utils.ts

@@ -3,7 +3,13 @@
  * Utility functions for M3U8 playlist manipulation
  */
 
-import { parseBlocks, learnMainPattern, scoreBlock, shouldFilterBlock } from './m3u8-ad-detector';
+import {
+    parseBlocks,
+    learnMainPattern,
+    scoreBlock,
+    shouldFilterBlock,
+    findDuplicateSignatureBlockIndices,
+} from './m3u8-ad-detector';
 
 const INTERSTITIAL_DATERANGE_MARKERS = [
     'class="com.apple.hls.interstitial"',
@@ -67,7 +73,7 @@ function isAuxiliaryAdMetadataLine(trimmedLine: string, normalizedKeywords: stri
  * 1. Keyword matching (configurable via env)
  * 2. CUE-OUT/CUE-IN standard tags
  * 3. HLS interstitial metadata removal
- * 4. Heuristic block analysis (filename patterns, ad path keywords)
+ * 4. Heuristic block analysis (filename patterns, ad path keywords, duration signature fingerprints)
  * 
  * Also converts relative URLs to absolute URLs for Blob playback.
  * 
@@ -113,9 +119,13 @@ export function filterM3u8Ad(content: string, baseUrl: string, mode: AdFilterMod
         const blocks = parseBlocks(lines);
         if (blocks.length > 0) {
             const mainPattern = learnMainPattern(blocks);
-            for (const block of blocks) {
+            const duplicateIndices = findDuplicateSignatureBlockIndices(blocks);
+
+            for (let blockIdx = 0; blockIdx < blocks.length; blockIdx++) {
+                const block = blocks[blockIdx];
+                const isDuplicate = duplicateIndices.has(blockIdx);
                 // Pass all keywords (including custom ones) to heuristic scorer
-                const score = scoreBlock(block, mainPattern, normalizedKeywords);
+                const score = scoreBlock(block, mainPattern, normalizedKeywords, isDuplicate);
                 const threshold = mode === 'aggressive' ? 3.0 : 5.0;
 
                 if (shouldFilterBlock(score, threshold)) {
@@ -125,8 +135,8 @@ export function filterM3u8Ad(content: string, baseUrl: string, mode: AdFilterMod
                         adLineIndices.add(segment.lineIndex - 1); // EXTINF line
                     }
                 } else if (block.segments.length > 0) {
-                    // Segment-level detection: 
-                    // Even if the whole block didn't trigger, check segments individually 
+                    // Segment-level detection:
+                    // Even if the whole block didn't trigger, check segments individually
                     // if it's a suspicious single-segment "block" (common for ads without discontinuity)
                     for (const segment of block.segments) {
                         const singleSegmentBlock = {