feat: support serverControl and preloadSegment behind experimentalLLH…

…LS flag (#1078)

src/manifest.js

@@ -78,6 +78,19 @@ export const parseManifest = ({
       });
     }
   }
+  if (!manifest.targetDuration) {
+    let targetDuration = 10;
+
+    if (manifest.segments && manifest.segments.length) {
+      targetDuration = manifest
+        .segments.reduce((acc, s) => Math.max(acc, s.duration), 0);
+    }
+
+    if (onwarn) {
+      onwarn(`manifest has no targetDuration defaulting to ${targetDuration}`);
+    }
+    manifest.targetDuration = targetDuration;
+  }
 
   return manifest;
 };

src/master-playlist-controller.js

@@ -1311,8 +1311,12 @@ export class MasterPlaylistController extends videojs.EventTarget {
       return;
     }
 
-    const suggestedPresentationDelay = this.masterPlaylistLoader_.master.suggestedPresentationDelay;
-    const mainSeekable = Vhs.Playlist.seekable(media, expired, suggestedPresentationDelay);
+    const master = this.masterPlaylistLoader_.master;
+    const mainSeekable = Vhs.Playlist.seekable(
+      media,
+      expired,
+      Vhs.Playlist.liveEdgeDelay(master, media)
+    );
 
     if (mainSeekable.length === 0) {
       return;
@@ -1326,7 +1330,11 @@ export class MasterPlaylistController extends videojs.EventTarget {
         return;
       }
 
-      audioSeekable = Vhs.Playlist.seekable(media, expired, suggestedPresentationDelay);
+      audioSeekable = Vhs.Playlist.seekable(
+        media,
+        expired,
+        Vhs.Playlist.liveEdgeDelay(master, media)
+      );
 
       if (audioSeekable.length === 0) {
         return;

src/playlist-loader.js

@@ -83,7 +83,7 @@ export const updateSegments = (original, update, offset) => {
 };
 
 export const resolveSegmentUris = (segment, baseUri) => {
-  // preloadSegments will not have a uri at all
+  // preloadSegment will not have a uri at all
   // as the segment isn't actually in the manifest yet, only parts
   if (!segment.resolvedUri && segment.uri) {
     segment.resolvedUri = resolveUrl(baseUri, segment.uri);
@@ -113,6 +113,19 @@ export const resolveSegmentUris = (segment, baseUri) => {
   }
 };
 
+const getAllSegments = function(media) {
+  const segments = media.segments || [];
+
+  // a preloadSegment with only preloadHints is not currently
+  // a usable segment, only include a preloadSegment that has
+  // parts.
+  if (media.preloadSegment && media.preloadSegment.parts) {
+    segments.push(media.preloadSegment);
+  }
+
+  return segments;
+};
+
 // consider the playlist unchanged if the playlist object is the same or
 // the number of segments is equal, the media sequence number is unchanged,
 // and this playlist hasn't become the end of the playlist
@@ -147,6 +160,8 @@ export const updateMaster = (master, media, unchangedCheck = isPlaylistUnchanged
 
   const mergedPlaylist = mergeOptions(playlist, media);
 
+  media.segments = getAllSegments(media);
+
   // if the update could overlap existing segment information, merge the two segment lists
   if (playlist.segments) {
     mergedPlaylist.segments = updateSegments(
@@ -188,16 +203,16 @@ export const updateMaster = (master, media, unchangedCheck = isPlaylistUnchanged
  */
 export const refreshDelay = (media, update) => {
   const lastSegment = media.segments[media.segments.length - 1];
-  let delay;
-
-  if (update && lastSegment && lastSegment.duration) {
-    delay = lastSegment.duration * 1000;
-  } else {
-    // if the playlist is unchanged since the last reload or last segment duration
-    // cannot be determined, try again after half the target duration
-    delay = (media.targetDuration || 10) * 500;
+  const lastPart = lastSegment && lastSegment.parts && lastSegment.parts[lastSegment.parts.length - 1];
+  const lastDuration = lastPart && lastPart.duration || lastSegment && lastSegment.duration;
+
+  if (update && lastDuration) {
+    return lastDuration * 1000;
   }
-  return delay;
+
+  // if the playlist is unchanged since the last reload or last segment duration
+  // cannot be determined, try again after half the target duration
+  return (media.partTargetDuration || media.targetDuration || 10) * 500;
 };
 
 /**
@@ -326,7 +341,7 @@ export default class PlaylistLoader extends EventTarget {
     // merge this playlist into the master
     const update = updateMaster(this.master, playlist);
 
-    this.targetDuration = playlist.targetDuration;
+    this.targetDuration = playlist.partTargetDuration || playlist.targetDuration;
 
     if (update) {
       this.master = update;
@@ -405,7 +420,7 @@ export default class PlaylistLoader extends EventTarget {
     window.clearTimeout(this.finalRenditionTimeout);
 
     if (shouldDelay) {
-      const delay = (playlist.targetDuration / 2) * 1000 || 5 * 1000;
+      const delay = ((playlist.partTargetDuration || playlist.targetDuration) / 2) * 1000 || 5 * 1000;
 
       this.finalRenditionTimeout =
         window.setTimeout(this.media.bind(this, playlist, false), delay);
@@ -538,7 +553,7 @@ export default class PlaylistLoader extends EventTarget {
     const media = this.media();
 
     if (shouldDelay) {
-      const delay = media ? (media.targetDuration / 2) * 1000 : 5 * 1000;
+      const delay = media ? ((media.partTargetDuration || media.targetDuration) / 2) * 1000 : 5 * 1000;
 
       this.mediaUpdateTimeout = window.setTimeout(() => this.load(), delay);
       return;
@@ -660,11 +675,11 @@ export default class PlaylistLoader extends EventTarget {
       // then resolve URIs in advance, as they are usually done after a playlist request,
       // which may not happen if the playlist is resolved.
       manifest.playlists.forEach((playlist) => {
-        if (playlist.segments) {
-          playlist.segments.forEach((segment) => {
-            resolveSegmentUris(segment, playlist.resolvedUri);
-          });
-        }
+        playlist.segments = getAllSegments(playlist);
+
+        playlist.segments.forEach((segment) => {
+          resolveSegmentUris(segment, playlist.resolvedUri);
+        });
       });
       this.trigger('loadedplaylist');
       if (!this.request) {

src/playlist.js

@@ -9,6 +9,62 @@ import {TIME_FUDGE_FACTOR} from './ranges.js';
 
 const {createTimeRange} = videojs;
 
+/**
+ * A function to get a combined list of parts and segments with durations
+ * and indexes.
+ *
+ * @param {Playlist} playlist the playlist to get the list for.
+ *
+ * @return {Array} The part/segment list.
+ */
+const getPartsAndSegments = (playlist) => (playlist.segments || []).reduce((acc, segment, si) => {
+  if (segment.parts) {
+    segment.parts.forEach(function(part, pi) {
+      acc.push({duration: part.duration, segmentIndex: si, partIndex: pi});
+    });
+  } else {
+    acc.push({duration: segment.duration, segmentIndex: si, partIndex: null});
+  }
+  return acc;
+}, []);
+
+/**
+ * Get the number of seconds to delay from the end of a
+ * live playlist.
+ *
+ * @param {Playlist} master the master playlist
+ * @param {Playlist} media the media playlist
+ * @return {number} the hold back in seconds.
+ */
+export const liveEdgeDelay = (master, media) => {
+  if (media.endList) {
+    return 0;
+  }
+
+  // dash suggestedPresentationDelay trumps everything
+  if (master && master.suggestedPresentationDelay) {
+    return master.suggestedPresentationDelay;
+  }
+
+  const lastSegment = media.segments && media.segments.length && media.segments[media.segments.length - 1];
+  const hasParts = lastSegment && lastSegment.parts && lastSegment.parts.length;
+
+  // look for "part" delays from ll-hls first
+  if (hasParts && media.serverControl && media.serverControl.partHoldBack) {
+    return media.serverControl.partHoldBack;
+  } else if (hasParts && media.partTargetDuration) {
+    return media.partTargetDuration * 3;
+
+  // finally look for full segment delays
+  } else if (media.serverControl && media.serverControl.holdBack) {
+    return media.serverControl.holdBack;
+  } else if (media.targetDuration) {
+    return media.targetDuration * 3;
+  }
+
+  return 0;
+};
+
 /**
  * walk backward until we find a duration we can use
  * or return a failure
@@ -252,17 +308,9 @@ export const playlistEnd = function(playlist, expired, useSafeLiveEnd, liveEdgeP
     expired
   );
 
-  // "The client SHALL choose which Media Segment to play first from the
-  // Media Playlist when playback starts.  If the EXT-X-ENDLIST tag is not
-  // present and the client intends to play the media normally, the client
-  // SHOULD NOT choose a segment which starts less than three target
-  // durations from the end of the Playlist file.  Doing so can trigger
-  // playback stalls."
-  // https://tools.ietf.org/html/draft-pantos-http-live-streaming-23#section-6.3.3
   if (useSafeLiveEnd) {
-    liveEdgePadding = typeof liveEdgePadding === 'number' ? liveEdgePadding : playlist.targetDuration * 3;
+    liveEdgePadding = typeof liveEdgePadding === 'number' ? liveEdgePadding : liveEdgeDelay(null, playlist);
     lastSegmentTime -= liveEdgePadding;
-
   }
 
   // don't return a time less than zero
@@ -314,31 +362,34 @@ export const getMediaInfoForTime = function(
   startIndex,
   startTime
 ) {
-  let i;
-  let segment;
-  const numSegments = playlist.segments.length;
 
+  const partsAndSegments = getPartsAndSegments(playlist);
   let time = currentTime - startTime;
 
   if (time < 0) {
     // Walk backward from startIndex in the playlist, adding durations
     // until we find a segment that contains `time` and return it
     if (startIndex > 0) {
-      for (i = startIndex - 1; i >= 0; i--) {
-        segment = playlist.segments[i];
+      for (let i = startIndex - 1; i >= 0; i--) {
+        const segment = partsAndSegments[i];
+
         time += (segment.duration + TIME_FUDGE_FACTOR);
+
         if (time > 0) {
           return {
-            mediaIndex: i,
-            startTime: startTime - sumDurations(playlist, startIndex, i)
+            mediaIndex: segment.segmentIndex,
+            startTime: startTime - sumDurations(playlist, startIndex, segment.segmentIndex),
+            partIndex: segment.partIndex
           };
         }
       }
     }
+
     // We were unable to find a good segment within the playlist
     // so select the first segment
     return {
-      mediaIndex: 0,
+      mediaIndex: partsAndSegments[0] && partsAndSegments[0].segmentIndex || 0,
+      partIndex: partsAndSegments[0] && partsAndSegments[0].partIndex || null,
       startTime: currentTime
     };
   }
@@ -347,11 +398,11 @@ export const getMediaInfoForTime = function(
   // adding target durations. If we "run out of time" before getting to
   // the first segment, return the first segment
   if (startIndex < 0) {
-    for (i = startIndex; i < 0; i++) {
+    for (let i = startIndex; i < 0; i++) {
       time -= playlist.targetDuration;
       if (time < 0) {
         return {
-          mediaIndex: 0,
+          mediaIndex: partsAndSegments[0].segmentIndex,
           startTime: currentTime
         };
       }
@@ -361,20 +412,24 @@ export const getMediaInfoForTime = function(
 
   // Walk forward from startIndex in the playlist, subtracting durations
   // until we find a segment that contains `time` and return it
-  for (i = startIndex; i < numSegments; i++) {
-    segment = playlist.segments[i];
-    time -= segment.duration + TIME_FUDGE_FACTOR;
+  for (let i = startIndex; i < partsAndSegments.length; i++) {
+    const partSegment = partsAndSegments[i];
+
+    time -= partSegment.duration + TIME_FUDGE_FACTOR;
+
     if (time < 0) {
       return {
-        mediaIndex: i,
-        startTime: startTime + sumDurations(playlist, startIndex, i)
+        mediaIndex: partSegment.segmentIndex,
+        startTime: startTime + sumDurations(playlist, startIndex, partSegment.segmentIndex),
+        partIndex: partSegment.partIndex
       };
     }
   }
 
   // We are out of possible candidates so load the last one...
   return {
-    mediaIndex: numSegments - 1,
+    mediaIndex: partsAndSegments[partsAndSegments.length - 1].segmentIndex,
+    partIndex: partsAndSegments[partsAndSegments.length - 1].partIndex,
     startTime: currentTime
   };
 };
@@ -510,6 +565,7 @@ export const isLowestEnabledRendition = (master, media) => {
 
 // exports
 export default {
+  liveEdgeDelay,
   duration,
   seekable,
   getMediaInfoForTime,