feat: Update usage of minBufferTime according to the DASH spec (#7616)

Related to
#7602 (comment)

From 23009-1:

The value of the minimum buffer time does not provide any instructions
to the client on how long
to buffer the media. The value however describes how much buffer a
client should have under
ideal network conditions. As such, MBT is not describing the burstiness
or jitter in the network,
it is describing the burstiness or jitter in the content encoding.
Together with the BW value, it is
a property of the content. Using the "leaky bucket" model, it is the
size of the bucket that makes
    BW true, given the way the content is encoded

docs/tutorials/faq.md

@@ -191,19 +191,6 @@ the ad blocker in compiled mode as well.
 
 <hr>
 
-**Q:** Why does some DASH content take a long time to start playback?
-
-**A:** Shaka Player honors the `minBufferTime` field in DASH.  If this field is
-set to a large value, Shaka Player will buffer that much content before
-beginning playback.  To override this behavior and ignore the `minBufferTime`
-field, we offer the following configuration:
-
-```js
-player.configure('manifest.dash.ignoreMinBufferTime', true);
-```
-
-<hr>
-
 **Q:** My HLS stream is failing on Chrome, with a chunk demuxer append failed
 error.
 

docs/tutorials/manifest-parser.md

@@ -256,7 +256,6 @@ MyManifestParser.prototype.loadManifest_ = function(data) {
 
   return {
     presentationTimeline: timeline,
-    minBufferTime: 5,  // seconds
     offlineSessionIds: [],
     variants: [
       this.loadVariant_(true, true),

docs/tutorials/network-and-buffering-config.md

@@ -73,9 +73,6 @@ This is a minimum; if the stream's max segment size is longer than the
 
 *NOTES:*
  - *`rebufferingGoal` should always be less than `bufferingGoal`.*
- - *A DASH manifest's `minBufferTime`, if greater, overrides `rebufferingGoal`.*
- - *You can ignore `minBufferTime` by setting the
-   `manifest.dash.ignoreMinBufferTime` configuration to true.*
 
 All of these settings should be customized for your application.  The default
 values are very conservative.

externs/shaka/manifest.js

@@ -17,7 +17,6 @@
  *   textStreams: !Array.<shaka.extern.Stream>,
  *   imageStreams: !Array.<shaka.extern.Stream>,
  *   offlineSessionIds: !Array.<string>,
- *   minBufferTime: number,
  *   sequenceMode: boolean,
  *   ignoreManifestTimestampsInSegmentsMode: boolean,
  *   type: string,
@@ -76,11 +75,6 @@
  * @property {!Array.<string>} offlineSessionIds
  *   <i>Defaults to [].</i> <br>
  *   An array of EME sessions to load for offline playback.
- * @property {number} minBufferTime
- *   <i>Defaults to 0.</i> <br>
- *   The minimum number of seconds of content that must be buffered before
- *   playback can begin.  Can be overridden by a higher value from the Player
- *   configuration.
  * @property {boolean} sequenceMode
  *   If true, we will append the media segments using sequence mode; that is to
  *   say, ignoring any timestamps inside the media files.

externs/shaka/player.js

@@ -1104,8 +1104,7 @@ shaka.extern.xml.Node;
  *   Defaults to <code>false</code>.
  * @property {boolean} ignoreMinBufferTime
  *   If true will cause DASH parser to ignore <code>minBufferTime</code> from
- *   manifest. It allows player config to take precedence over manifest for
- *   <code>rebufferingGoal</code>.
+ *   manifest.
  *   <br>
  *   Defaults to <code>false</code>.
  * @property {boolean} autoCorrectDrift

lib/dash/dash_parser.js

@@ -643,13 +643,6 @@ shaka.dash.DashParser = class {
     }
     this.manifestPatchContext_.availabilityTimeOffset = availabilityTimeOffset;
 
-    const ignoreMinBufferTime = this.config_.dash.ignoreMinBufferTime;
-    let minBufferTime = 0;
-    if (!ignoreMinBufferTime) {
-      minBufferTime =
-          TXml.parseAttr(mpd, 'minBufferTime', TXml.parseDuration) || 0;
-    }
-
     this.updatePeriod_ = /** @type {number} */ (TXml.parseAttr(
         mpd, 'minimumUpdatePeriod', TXml.parseDuration, -1));
 
@@ -702,6 +695,12 @@ shaka.dash.DashParser = class {
         }
       }
     } else {
+      const ignoreMinBufferTime = this.config_.dash.ignoreMinBufferTime;
+      let minBufferTime = 0;
+      if (!ignoreMinBufferTime) {
+        minBufferTime =
+            TXml.parseAttr(mpd, 'minBufferTime', TXml.parseDuration) || 0;
+      }
       // DASH IOP v3.0 suggests using a default delay between minBufferTime
       // and timeShiftBufferDepth.  This is literally the range of all
       // feasible choices for the value.  Nothing older than
@@ -799,10 +798,7 @@ shaka.dash.DashParser = class {
 
     await contentSteeringPromise;
 
-    // Set minBufferTime to 0 for low-latency DASH live stream to achieve the
-    // best latency
     if (this.lowLatencyMode_) {
-      minBufferTime = 0;
       const presentationDelay = suggestedPresentationDelay != null ?
           suggestedPresentationDelay : this.config_.defaultPresentationDelay;
       presentationTimeline.setDelay(presentationDelay);
@@ -818,7 +814,6 @@ shaka.dash.DashParser = class {
         textStreams: this.periodCombiner_.getTextStreams(),
         imageStreams: this.periodCombiner_.getImageStreams(),
         offlineSessionIds: [],
-        minBufferTime: minBufferTime || 0,
         sequenceMode: this.config_.dash.sequenceMode,
         ignoreManifestTimestampsInSegmentsMode: false,
         type: shaka.media.ManifestParser.DASH,

lib/hls/hls_parser.js

@@ -1002,7 +1002,6 @@ shaka.hls.HlsParser = class {
       textStreams,
       imageStreams,
       offlineSessionIds: [],
-      minBufferTime: 0,
       sequenceMode: this.config_.hls.sequenceMode,
       ignoreManifestTimestampsInSegmentsMode:
         this.config_.hls.ignoreManifestTimestampsInSegmentsMode,

lib/media/playhead.js

@@ -231,9 +231,6 @@ shaka.media.MediaSourcePlayhead = class {
     /** @private {shaka.media.PresentationTimeline} */
     this.timeline_ = manifest.presentationTimeline;
 
-    /** @private {number} */
-    this.minBufferTime_ = manifest.minBufferTime || 0;
-
     /** @private {?shaka.extern.StreamingConfiguration} */
     this.config_ = config;
 
@@ -482,10 +479,7 @@ shaka.media.MediaSourcePlayhead = class {
     const isBuffered = (playheadTime) => shaka.media.TimeRangesUtils.isBuffered(
         this.mediaElement_.buffered, playheadTime);
 
-    const rebufferingGoal = Math.max(
-        this.minBufferTime_,
-        this.config_.rebufferingGoal);
-
+    const rebufferingGoal = this.config_.rebufferingGoal;
     const safeSeekOffset = this.config_.safeSeekOffset;
 
     let start = this.timeline_.getSeekRangeStart();

lib/media/streaming_engine.js

@@ -779,9 +779,7 @@ shaka.media.StreamingEngine = class {
     // If the new segment can be finished in time without risking a buffer
     // underflow, we should abort the old one and switch.
     const bufferedAhead = (bufferEnd || 0) - presentationTime;
-    const safetyBuffer = Math.max(
-        this.manifest_.minBufferTime || 0,
-        this.config_.rebufferingGoal);
+    const safetyBuffer = this.config_.rebufferingGoal;
     const safeBufferedAhead = bufferedAhead - safetyBuffer;
     if (timeToFetchNewSegment < safeBufferedAhead) {
       return true;
@@ -1366,9 +1364,7 @@ shaka.media.StreamingEngine = class {
         'bufferedAhead=' + bufferedAhead);
 
     const unscaledBufferingGoal = Math.max(
-        this.manifest_.minBufferTime || 0,
-        this.config_.rebufferingGoal,
-        this.config_.bufferingGoal);
+        this.config_.rebufferingGoal, this.config_.bufferingGoal);
 
     const scaledBufferingGoal = Math.max(1,
         unscaledBufferingGoal * this.bufferingScale_);

lib/mss/mss_parser.js

@@ -431,7 +431,6 @@ shaka.mss.MssParser = class {
         textStreams: context.textStreams,
         imageStreams: [],
         offlineSessionIds: [],
-        minBufferTime: 0,
         sequenceMode: this.config_.mss.sequenceMode,
         ignoreManifestTimestampsInSegmentsMode: false,
         type: shaka.media.ManifestParser.MSS,

lib/offline/manifest_converter.js

@@ -84,7 +84,6 @@ shaka.offline.ManifestConverter = class {
 
     return {
       presentationTimeline: timeline,
-      minBufferTime: 2,
       offlineSessionIds: manifestDB.sessionIds,
       variants: Array.from(variants.values()),
       textStreams: textStreams,

lib/player.js

@@ -2649,13 +2649,8 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
       this.playheadObservers_ =
           this.createPlayheadObserversForMSE_(startTime);
 
-      // We need to start the buffer management code near the end because it
-      // will set the initial buffering state and that depends on other
-      // components being initialized.
-      const rebufferThreshold = Math.max(
-          this.manifest_.minBufferTime,
-          this.config_.streaming.rebufferingGoal);
-      this.startBufferManagement_(mediaElement, rebufferThreshold);
+      this.startBufferManagement_(
+          mediaElement, this.config_.streaming.rebufferingGoal);
     };
 
     if (!this.config_.streaming.startAtSegmentBoundary) {
@@ -4207,12 +4202,7 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
       this.onAbrStatusChanged_();
     }
     if (this.bufferObserver_) {
-      let rebufferThreshold = this.config_.streaming.rebufferingGoal;
-      if (this.manifest_) {
-        rebufferThreshold =
-            Math.max(rebufferThreshold, this.manifest_.minBufferTime);
-      }
-      this.updateBufferingSettings_(rebufferThreshold);
+      this.updateBufferingSettings_(this.config_.streaming.rebufferingGoal);
     }
 
     if (this.manifest_) {

test/dash/dash_parser_manifest_unit.js

@@ -170,7 +170,6 @@ describe('DashParser Manifest', () => {
           manifest.sequenceMode = true;
           manifest.type = shaka.media.ManifestParser.DASH;
           manifest.anyTimeline();
-          manifest.minBufferTime = 75;
           manifest.addPartialVariant((variant) => {
             variant.language = 'en';
             variant.bandwidth = 200;
@@ -256,7 +255,6 @@ describe('DashParser Manifest', () => {
           manifest.sequenceMode = false;
           manifest.type = shaka.media.ManifestParser.DASH;
           manifest.anyTimeline();
-          manifest.minBufferTime = 75;
           manifest.addPartialVariant((variant) => {
             variant.language = 'en';
             variant.bandwidth = 200;
@@ -1759,56 +1757,6 @@ describe('DashParser Manifest', () => {
     expect(stream).toBeUndefined();
   });
 
-  it('override manifest value if ignoreMinBufferTime is true', async () => {
-    const manifestText = [
-      '<MPD minBufferTime="PT75S">',
-      '  <Period id="1" duration="PT30S">',
-      '    <AdaptationSet id="1" mimeType="video/mp4">',
-      '      <Representation id="video-sd" width="640" height="480">',
-      '        <BaseURL>v-sd.mp4</BaseURL>',
-      '        <SegmentBase indexRange="100-200" />',
-      '      </Representation>',
-      '    </AdaptationSet>',
-      '  </Period>',
-      '</MPD>',
-    ].join('\n');
-
-    fakeNetEngine.setResponseText('dummy://foo', manifestText);
-    const config = shaka.util.PlayerConfiguration.createDefault().manifest;
-    config.dash.ignoreMinBufferTime = true;
-    parser.configure(config);
-
-    /** @type {shaka.extern.Manifest} */
-    const manifest = await parser.start('dummy://foo', playerInterface);
-    const minBufferTime = manifest.minBufferTime;
-    expect(minBufferTime).toBe(0);
-  });
-
-  it('get manifest value if ignoreMinBufferTime is false', async () => {
-    const manifestText = [
-      '<MPD minBufferTime="PT75S">',
-      '  <Period id="1" duration="PT30S">',
-      '    <AdaptationSet id="1" mimeType="video/mp4">',
-      '      <Representation id="video-sd" width="640" height="480">',
-      '        <BaseURL>v-sd.mp4</BaseURL>',
-      '        <SegmentBase indexRange="100-200" />',
-      '      </Representation>',
-      '    </AdaptationSet>',
-      '  </Period>',
-      '</MPD>',
-    ].join('\n');
-
-    fakeNetEngine.setResponseText('dummy://foo', manifestText);
-    const config = shaka.util.PlayerConfiguration.createDefault().manifest;
-    config.dash.ignoreMinBufferTime = false;
-    parser.configure(config);
-
-    /** @type {shaka.extern.Manifest} */
-    const manifest = await parser.start('dummy://foo', playerInterface);
-    const minBufferTime = manifest.minBufferTime;
-    expect(minBufferTime).toBe(75);
-  });
-
   it('honors the ignoreMaxSegmentDuration config', async () => {
     const manifestText = [
       '<MPD maxSegmentDuration="PT5S">',
@@ -1944,7 +1892,7 @@ describe('DashParser Manifest', () => {
     const manifest = await parser.start('dummy://foo', playerInterface);
     const presentationTimeline = manifest.presentationTimeline;
     const presentationDelay = presentationTimeline.getDelay();
-    expect(presentationDelay).toBe(1.5*manifest.minBufferTime);
+    expect(presentationDelay).toBe(3);
   });
 
   it('Honors the ignoreEmptyAdaptationSet config', async () => {

test/media/playhead_unit.js

@@ -131,7 +131,6 @@ describe('Playhead', () => {
       textStreams: [],
       imageStreams: [],
       presentationTimeline: timeline,
-      minBufferTime: 10,
       offlineSessionIds: [],
       sequenceMode: false,
       ignoreManifestTimestampsInSegmentsMode: false,
@@ -405,6 +404,8 @@ describe('Playhead', () => {
     timeline.getSeekRangeStart.and.returnValue(5);
     timeline.getSeekRangeEnd.and.returnValue(60);
 
+    config.rebufferingGoal = 10;
+
     playhead = new shaka.media.MediaSourcePlayhead(
         video,
         manifest,

test/media/streaming_engine_integration.js

@@ -598,7 +598,6 @@ describe('StreamingEngine', () => {
       return {
         presentationTimeline: timeline,
         offlineSessionIds: [],
-        minBufferTime: 2,
         textStreams: [],
         imageStreams: [],
         sequenceMode: false,

test/media/streaming_engine_unit.js

@@ -2641,8 +2641,6 @@ describe('StreamingEngine', () => {
     beforeEach(() => {
       setupVod();
 
-      manifest.minBufferTime = 1;
-
       config = shaka.util.PlayerConfiguration.createDefault().streaming;
       config.rebufferingGoal = 1;
       config.bufferingGoal = 1;
@@ -2752,8 +2750,6 @@ describe('StreamingEngine', () => {
     it('does not fail immediately', async () => {
       setupVod();
 
-      manifest.minBufferTime = 1;
-
       // Create StreamingEngine.
       const config = shaka.util.PlayerConfiguration.createDefault().streaming;
       config.rebufferingGoal = 1;
@@ -2816,8 +2812,6 @@ describe('StreamingEngine', () => {
     it('fails after multiple QuotaExceededError', async () => {
       setupVod();
 
-      manifest.minBufferTime = 1;
-
       // Create StreamingEngine.
       const config = shaka.util.PlayerConfiguration.createDefault().streaming;
       config.rebufferingGoal = 1;

test/offline/storage_compatibility_unit.js

@@ -279,7 +279,6 @@ filterDescribe('Storage Compatibility', offlineSupported, () => {
 
       const expected = shaka.test.ManifestGenerator.generate((manifest) => {
         manifest.anyTimeline();
-        manifest.minBufferTime = 2;
 
         manifest.addPartialVariant((variant) => {
           variant.addPartialStream(ContentType.VIDEO, (stream) => {

test/test/util/manifest_generator.js

@@ -93,8 +93,6 @@ shaka.test.ManifestGenerator.Manifest = class {
     this.presentationTimeline = timeline;
     /** @type {!Array.<string>} */
     this.offlineSessionIds = [];
-    /** @type {number} */
-    this.minBufferTime = 0;
     /** @type {boolean} */
     this.sequenceMode = false;
     /** @type {boolean} */

test/test/util/streaming_engine_util.js

@@ -329,7 +329,6 @@ shaka.test.StreamingEngineUtil = class {
     /** @type {shaka.extern.Manifest} */
     const manifest = {
       presentationTimeline,
-      minBufferTime: 2,
       offlineSessionIds: [],
       variants: [],
       textStreams: [],