From 53d6378bac540af8e69522d1e22887b56b598bf0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=81lvaro=20Velad=20Galv=C3=A1n?= <ladvan91@hotmail.com>
Date: Thu, 22 Jun 2023 12:49:26 +0200
Subject: [PATCH] feat(HLS): Optimize LL-HLS with byterange (#5342)

- Mark the the full segment as preload if it has some partial preload
segment
- Request _HLS_part=0 when using LL-HLS byterange optimization
---
 lib/hls/hls_parser.js     | 9 +++++++++
 test/hls/hls_live_unit.js | 1 +
 2 files changed, 10 insertions(+)

diff --git a/lib/hls/hls_parser.js b/lib/hls/hls_parser.js
index 277f7e8615..35451eb4d1 100644
--- a/lib/hls/hls_parser.js
+++ b/lib/hls/hls_parser.js
@@ -2360,6 +2360,9 @@ shaka.hls.HlsParser = class {
     const partialReferences = lastSegment.partialReferences;
     if (!lastSegment.partialReferences.length) {
       nextMediaSequence++;
+      if (lastSegment.hasByterangeOptimization()) {
+        nextPart = 0;
+      }
       return {
         nextMediaSequence,
         nextPart,
@@ -2844,6 +2847,7 @@ shaka.hls.HlsParser = class {
     let segmentWithByteRangeOptimization = false;
     let getUrisOptimization = null;
     let somePartialSegmentWithGap = false;
+    let isPreloadSegment = false;
 
     if (this.lowLatencyMode_ && hlsSegment.partialSegments.length) {
       const byterangeOptimizationSupport = (mimeType == 'video/mp4' ||
@@ -2937,6 +2941,7 @@ shaka.hls.HlsParser = class {
             hlsAes128Key);
         if (item.name == 'EXT-X-PRELOAD-HINT') {
           partial.markAsPreload();
+          isPreloadSegment = true;
         }
         // The spec doesn't say that we can assume INDEPENDENT=YES for the
         // first partial segment. It does call the flag "optional", though, and
@@ -3043,6 +3048,10 @@ shaka.hls.HlsParser = class {
 
     if (segmentWithByteRangeOptimization) {
       reference.markAsByterangeOptimization();
+
+      if (isPreloadSegment) {
+        reference.markAsPreload();
+      }
     }
 
     return reference;
diff --git a/test/hls/hls_live_unit.js b/test/hls/hls_live_unit.js
index 7e867ec33b..de6279371c 100644
--- a/test/hls/hls_live_unit.js
+++ b/test/hls/hls_live_unit.js
@@ -722,6 +722,7 @@ describe('HlsParser live', () => {
             /* baseUri= */ '', /* startByte= */ 0, /* endByte= */ null,
             /* timestampOffset= */ 0);
         ref2.markAsByterangeOptimization();
+        ref2.markAsPreload();
 
         await testInitialManifest(master, mediaWithPartialSegments,
             [ref, ref2]);