fix: live dash segment changes should be considered a playlist update

src/dash-playlist-loader.js

@@ -6,7 +6,8 @@ import {
 } from 'mpd-parser';
 import {
   refreshDelay,
-  updateMaster as updatePlaylist
+  updateMaster as updatePlaylist,
+  isPlaylistUnchanged
 } from './playlist-loader';
 import { resolveUrl, resolveManifestRedirect } from './resolve-url';
 import parseSidx from 'mux.js/lib/tools/parse-sidx';
@@ -21,6 +22,67 @@ import {toUint8} from '@videojs/vhs-utils/es/byte-helpers';
 
 const { EventTarget, mergeOptions } = videojs;
 
+const dashPlaylistUnchanged = function(a, b) {
+  if (!isPlaylistUnchanged(a, b)) {
+    return false;
+  }
+
+  // for dash the above check will often return true in scenarios where
+  // the playlist actually has changed because mediaSequence isn't a
+  // dash thing, and we often set it to 1. So if the playlists have the same amount
+  // of segments we return true.
+  // So for dash we need to make sure that the underlying segments are different.
+
+  // if sidx changed then the playlists are different.
+  if (a.sidx && b.sidx && (a.sidx.offset !== b.sidx.offset || a.sidx.length !== b.sidx.length)) {
+    return false;
+  } else if ((!a.sidx && b.sidx) || (a.sidx && !b.sidx)) {
+    return false;
+  }
+
+  // one or the other does not have segments
+  // there was a change.
+  if (a.segments && !b.segments || !a.segments && b.segments) {
+    return false;
+  }
+
+  // neither has segments nothing changed
+  if (!a.segments && !b.segments) {
+    return true;
+  }
+
+  // check segments themselves
+  for (let i = 0; i < a.segments.length; i++) {
+    const aSegment = a.segments[i];
+    const bSegment = b.segments[i];
+
+    // if uris are different between segments there was a change
+    if (aSegment.uri !== bSegment.uri) {
+      return false;
+    }
+
+    // neither segment has a byterange, there will be no byterange change.
+    if (!aSegment.byterange && !bSegment.byterange) {
+      continue;
+    }
+    const aByterange = aSegment.byterange;
+    const bByterange = bSegment.byterange;
+
+    // if byterange only exists on one of the segments, there was a change.
+    if ((aByterange && !bByterange) || (!aByterange && bByterange)) {
+      return false;
+    }
+
+    // if both segments have byterange with different offsets, there was a change.
+    if (aByterange.offset !== bByterange.offset || aByterange.length !== bByterange.length) {
+      return false;
+    }
+  }
+
+  // if everything was the same with segments, this is the same playlist.
+  return true;
+};
+
 /**
  * Parses the master XML string and updates playlist URI references.
  *
@@ -92,7 +154,7 @@ export const updateMaster = (oldMaster, newMaster, sidxMapping) => {
         addSidxSegmentsToPlaylist(playlist, sidxMapping[sidxKey].sidx, playlist.sidx.resolvedUri);
       }
     }
-    const playlistUpdate = updatePlaylist(update, playlist);
+    const playlistUpdate = updatePlaylist(update, playlist, dashPlaylistUnchanged);
 
     if (playlistUpdate) {
       update = playlistUpdate;
@@ -104,7 +166,7 @@ export const updateMaster = (oldMaster, newMaster, sidxMapping) => {
   forEachMediaGroup(newMaster, (properties, type, group, label) => {
     if (properties.playlists && properties.playlists.length) {
       const id = properties.playlists[0].id;
-      const playlistUpdate = updatePlaylist(update, properties.playlists[0]);
+      const playlistUpdate = updatePlaylist(update, properties.playlists[0], dashPlaylistUnchanged);
 
       if (playlistUpdate) {
         update = playlistUpdate;

src/playlist-loader.js

@@ -57,6 +57,14 @@ export const resolveSegmentUris = (segment, baseUri) => {
   }
 };
 
+// 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
+export const isPlaylistUnchanged = (a, b) => a === b ||
+  (a.segments && b.segments && a.segments.length === b.segments.length &&
+   a.endList === b.endList &&
+   a.mediaSequence === b.mediaSequence);
+
 /**
   * Returns a new master playlist that is the result of merging an
   * updated media playlist into the original version. If the
@@ -69,21 +77,15 @@ export const resolveSegmentUris = (segment, baseUri) => {
   * master playlist with the updated media playlist merged in, or
   * null if the merge produced no change.
   */
-export const updateMaster = (master, media) => {
+export const updateMaster = (master, media, unchangedCheck = isPlaylistUnchanged) => {
   const result = mergeOptions(master, {});
   const playlist = result.playlists[media.id];
 
   if (!playlist) {
     return null;
   }
 
-  // consider the playlist unchanged if the number of segments is equal, the media
-  // sequence number is unchanged, and this playlist hasn't become the end of the playlist
-  if (playlist.segments &&
-      media.segments &&
-      playlist.segments.length === media.segments.length &&
-      playlist.endList === media.endList &&
-      playlist.mediaSequence === media.mediaSequence) {
+  if (unchangedCheck(playlist, media)) {
     return null;
   }
 

test/dash-playlist-loader.test.js

@@ -1684,6 +1684,164 @@ QUnit.test('refreshXml_: updates media playlist reference if master changed', fu
   );
 });
 
+QUnit.test('refreshXml_: updates playlists if segment uri changed, but media sequence did not', function(assert) {
+  const loader = new DashPlaylistLoader('dash.mpd', this.fakeVhs);
+
+  loader.load();
+  this.standardXHRResponse(this.requests.shift());
+
+  const oldMaster = loader.master;
+  const oldMedia = loader.media();
+
+  // change segment uris
+  const newMasterXml = loader.masterXml_
+    .replace(/\$RepresentationID\$/g, '$RepresentationID$-foo')
+    .replace('media="segment-$Number$.mp4"', 'media="segment-foo$Number$.mp4"');
+
+  loader.refreshXml_();
+
+  assert.strictEqual(this.requests.length, 1, 'manifest is being requested');
+
+  this.requests.shift().respond(200, null, newMasterXml);
+
+  const newMaster = loader.master;
+  const newMedia = loader.media();
+
+  assert.notEqual(newMaster, oldMaster, 'master changed');
+  assert.notEqual(newMedia, oldMedia, 'media changed');
+  assert.equal(
+    newMedia,
+    newMaster.playlists[newMedia.id],
+    'media from updated master'
+  );
+});
+
+QUnit.test('refreshXml_: updates playlists if sidx changed', function(assert) {
+  const loader = new DashPlaylistLoader('dash-sidx.mpd', this.fakeVhs);
+
+  loader.load();
+  this.standardXHRResponse(this.requests.shift());
+  this.standardXHRResponse(this.requests.shift(), mp4VideoInitSegment().subarray(0, 10));
+  this.standardXHRResponse(this.requests.shift(), sidxResponse());
+
+  const oldMaster = loader.master;
+  const oldMedia = loader.media();
+
+  const newMasterXml = loader.masterXml_
+    .replace(/indexRange="200-399"/g, 'indexRange="500-699"');
+
+  loader.refreshXml_();
+
+  assert.strictEqual(this.requests.length, 1, 'manifest is being requested');
+
+  this.standardXHRResponse(this.requests.shift(), newMasterXml);
+
+  const newMaster = loader.master;
+  const newMedia = loader.media();
+
+  assert.notEqual(newMaster, oldMaster, 'master changed');
+  assert.notEqual(newMedia, oldMedia, 'media changed');
+  assert.equal(
+    newMedia,
+    newMaster.playlists[newMedia.id],
+    'media from updated master'
+  );
+});
+
+QUnit.test('refreshXml_: updates playlists if sidx removed', function(assert) {
+  const loader = new DashPlaylistLoader('dash-sidx.mpd', this.fakeVhs);
+
+  loader.load();
+  this.standardXHRResponse(this.requests.shift());
+  this.standardXHRResponse(this.requests.shift(), mp4VideoInitSegment().subarray(0, 10));
+  this.standardXHRResponse(this.requests.shift(), sidxResponse());
+
+  const oldMaster = loader.master;
+  const oldMedia = loader.media();
+
+  const newMasterXml = loader.masterXml_
+    .replace(/indexRange="200-399"/g, '');
+
+  loader.refreshXml_();
+
+  assert.strictEqual(this.requests.length, 1, 'manifest is being requested');
+
+  this.standardXHRResponse(this.requests.shift(), newMasterXml);
+
+  const newMaster = loader.master;
+  const newMedia = loader.media();
+
+  assert.notEqual(newMaster, oldMaster, 'master changed');
+  assert.notEqual(newMedia, oldMedia, 'media changed');
+  assert.equal(
+    newMedia,
+    newMaster.playlists[newMedia.id],
+    'media from updated master'
+  );
+});
+
+QUnit.test('refreshXml_: updates playlists if only segment byteranges change', function(assert) {
+  const loader = new DashPlaylistLoader('dashByterange.mpd', this.fakeVhs);
+
+  loader.load();
+  this.standardXHRResponse(this.requests.shift());
+
+  const oldMaster = loader.master;
+  const oldMedia = loader.media();
+
+  const newMasterXml = loader.masterXml_
+    .replace('mediaRange="12883295-13124492"', 'mediaRange="12883296-13124492"');
+
+  loader.refreshXml_();
+
+  assert.strictEqual(this.requests.length, 1, 'manifest is being requested');
+
+  this.standardXHRResponse(this.requests.shift(), newMasterXml);
+
+  const newMaster = loader.master;
+  const newMedia = loader.media();
+
+  assert.notEqual(newMaster, oldMaster, 'master changed');
+  assert.notEqual(newMedia, oldMedia, 'media changed');
+  assert.equal(
+    newMedia,
+    newMaster.playlists[newMedia.id],
+    'media from updated master'
+  );
+});
+
+QUnit.test('refreshXml_: updates playlists if sidx removed', function(assert) {
+  const loader = new DashPlaylistLoader('dash-sidx.mpd', this.fakeVhs);
+
+  loader.load();
+  this.standardXHRResponse(this.requests.shift());
+  this.standardXHRResponse(this.requests.shift(), mp4VideoInitSegment().subarray(0, 10));
+  this.standardXHRResponse(this.requests.shift(), sidxResponse());
+
+  const oldMaster = loader.master;
+  const oldMedia = loader.media();
+
+  const newMasterXml = loader.masterXml_
+    .replace(/indexRange="200-399"/g, '');
+
+  loader.refreshXml_();
+
+  assert.strictEqual(this.requests.length, 1, 'manifest is being requested');
+
+  this.standardXHRResponse(this.requests.shift(), newMasterXml);
+
+  const newMaster = loader.master;
+  const newMedia = loader.media();
+
+  assert.notEqual(newMaster, oldMaster, 'master changed');
+  assert.notEqual(newMedia, oldMedia, 'media changed');
+  assert.equal(
+    newMedia,
+    newMaster.playlists[newMedia.id],
+    'media from updated master'
+  );
+});
+
 QUnit.test('addSidxSegments_: updates master with sidx information', function(assert) {
   const loader = new DashPlaylistLoader('dash.mpd', this.fakeVhs);
   const sidxData = sidxResponse();

test/manifests/dashByterange.mpd

@@ -0,0 +1,58 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<MPD xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xmlns="urn:mpeg:DASH:schema:MPD:2011"
+    xsi:schemaLocation="urn:mpeg:DASH:schema:MPD:2011"
+    profiles="urn:mpeg:dash:profile:isoff-main:2011"
+    type="static"
+    mediaPresentationDuration="PT0H9M56.46S"
+    minBufferTime="PT15.0S">
+<BaseURL>http://www-itec.uni-klu.ac.at/ftp/datasets/mmsys12/BigBuckBunny/bunny_15s/</BaseURL>
+<Period start="PT0S">
+    <AdaptationSet bitstreamSwitching="true">
+        <Representation id="3" codecs="avc1" mimeType="video/mp4" width="480" height="360" startWithSAP="1" bandwidth="176031">
+            <SegmentList duration="15">
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="868-347185" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="347186-664464" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="664465-1027685" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="1027686-1367784" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="1367785-1677710" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="1677711-2001517" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="2001518-2290173" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="2290174-2634238" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="2634239-2985994" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="2985995-3323725" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="3323726-3650264" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="3650265-3978004" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="3978005-4304349" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="4304350-4629741" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="4629742-4951671" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="4951672-5282910" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="5282911-5629211" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="5629212-5963914" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="5963915-6312646" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="6312647-6612703" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="6612704-6923786" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="6923787-7272547" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="7272548-7590097" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="7590098-7947017" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="7947018-8276044" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="8276045-8551338" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="8551339-8866104" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="8866105-9171839" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="9171840-9515898" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="9515899-9849503" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="9849504-10161047" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="10161048-10494887" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="10494888-10786011" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="10786012-11142570" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="11142571-11503643" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="11503644-11859498" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="11859499-12213313" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="12213314-12578158" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="12578159-12883294" />
+                <SegmentURL media="bunny_15s_200kbit/bunny_200kbit_dashNonSeg.mp4" mediaRange="12883295-13124492" />
+            </SegmentList>
+        </Representation>
+    </AdaptationSet>
+</Period>
+</MPD>