dash.js
Open Source Media Player
Seamless and reliable DASH streaming on any browser-based device
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Performance issue with a DASH manifest containing a lot of inline SCTE35 events (increased load time)##### Environment
<!-- Replace [] with [x] to check off the list -->
- [x] The MPD passes the DASH-IF Conformance Tool on https://conformance.dashif.org/. Got issues related to shemeIdUri of the Accessibility tag (assuming minor)
- [] The stream has correct Access-Control-Allow-Origin headers (CORS)
- [] There are no network errors such as 404s in the browser console when trying to play the stream
- [x] The issue observed is not mentioned on https://github.com/Dash-Industry-Forum/dash.js/wiki/FAQ
- [x] The issue occurs in the latest reference client on http://reference.dashif.org/dash.js/ and not just on my page
* Link to playable MPD file: I can share a manifest privately but it won't be playable
* Dash.js version: v5.0.0 but issue is still there on the latest version
* Browser name/version: chrome v134.0
* OS name/version: MacOS Sequoia v15.3.2
##### Steps to reproduce
Just load the DASH manifest
##### Observed behavior
It takes more than 30s to trigger 400 inline SCTE35 events which delays by as much the playback on a Mac M1. And the same DASH manifest is even much much slower on a Smart TV
##### Console output
```
Debug.js:169 [16923][MediaPlayer] Streaming Initialized
Debug.js:169 [16926][EventController] Start Event Controller
Debug.js:169 [16927][MediaPlayer] Playback Initialized
Debug.js:169 [16984][ThroughputModel] Added throughput entry for stream: 68259 kbit/s
Debug.js:169 [17000][DashParser] Parsing complete: 14.9ms
Debug.js:169 [17001][StreamController] Manifest updated... updating data system wide.
Debug.js:169 [17003][ManifestUpdater] Manifest has been refreshed at Wed Apr 02 2025 11:59:53 GMT+0200 (Central European Summer Time)[1743587993.437]
Debug.js:169 [17044][TimeSyncController] Completed UTC sync. Setting client - server offset to 4
Debug.js:169 [17050][GapController] Starting the gap controller
Debug.js:169 [17050][StreamController] Switch to stream 1. Seektime is 1743449990.8983333, current playback time is null. Seamless period switch is set to false
Debug.js:169 [17050][MediaSourceController] Created MediaSource
Debug.js:169 [17050][StreamController] MediaSource attached to element. Waiting on open...
Debug.js:169 [17054][StreamController] MediaSource is open!
Debug.js:169 [17054][MediaSourceController] Set MediaSource duration:Infinity
Debug.js:169 [17055][EventController] Added inline event with id 2485543440 from period 1
Debug.js:169 [17055][EventController] Received event 2485543440
Debug.js:169 [17154][EventController] Added inline event with id 2700051282 from period 1
Debug.js:169 [17154][EventController] Received event 2700051282
Debug.js:169 [17243][EventController] Added inline event with id 4196740942 from period 1
Debug.js:169 [17243][EventController] Received event 4196740942
...
... removed similar inline event traces
...
Debug.js:169 [49240][EventController] Added inline event with id 3420840500 from period 1
Debug.js:169 [49240][EventController] Received event 3420840500
Debug.js:169 [49320][EventController] Added inline event with id 72744599 from period 1
Debug.js:169 [49320][EventController] Received event 72744599
Debug.js:169 [49400][EventController] Added inline event with id 1895730764 from period 1
Debug.js:169 [49400][EventController] Received event 1895730764
Debug.js:169 [49491][Stream] No muxed data.
Debug.js:169 [49491][Stream] No image data.
StreamController.js:469 [Violation] 'sourceopen' handler took 32436ms
Debug.js:169 [49493][DefaultProtectionModel] Requesting key system access for system string com.microsoft.playready
Debug.js:169 [49494][DefaultProtectionModel] Requesting key system access for system string com.microsoft.playready.recommendation
Debug.js:169 [49494][SourceBufferSink][text] Set MSE timestamp offset to 0
Debug.js:169 [49494][DefaultProtectionModel] Requesting key system access for system string com.widevine.alpha
DefaultProtectionModel.js:222 It is recommended that a robustness level be specified. Not specifying the robustness level could result in unexpected behavior.
_checkAccessForSystemStrings @ DefaultProtectionModel.js:222
(anonymous) @ DefaultProtectionModel.js:204
_checkAccessForKeySystem @ DefaultProtectionModel.js:203
_requestKeySystemAccessInternal @ DefaultProtectionModel.js:174
(anonymous) @ DefaultProtectionModel.js:186
Promise.catch
_requestKeySystemAccessInternal @ DefaultProtectionModel.js:184
(anonymous) @ DefaultProtectionModel.js:140
requestKeySystemAccess @ DefaultProtectionModel.js:139
_selectInitialKeySystem @ ProtectionController.js:209
_selectKeySystemOrUpdateKeySessions @ ProtectionController.js:180
handleKeySystemFromManifest @ ProtectionController.js:157
_initializationCompleted @ Stream.js:1031
_onDataUpdateCompleted @ Stream.js:897
(anonymous) @ EventBus.js:145
trigger @ EventBus.js:144
endDataUpdate @ RepresentationController.js:245
_onAllRepresentationsUpdated @ RepresentationController.js:126
(anonymous) @ RepresentationController.js:110
Promise.then
(anonymous) @ RepresentationController.js:109
updateData @ RepresentationController.js:90
(anonymous) @ StreamProcessor.js:696
selectMediaInfo @ StreamProcessor.js:668
_initializeMediaForType @ Stream.js:427
(anonymous) @ Stream.js:290
(anonymous) @ Stream.js:284
_commonMediaInitialization @ Stream.js:276
_initializeMedia @ Stream.js:265
(anonymous) @ Stream.js:213
activate @ Stream.js:197
_activateStream @ StreamController.js:527
_onMediaSourceOpen @ StreamController.js:496
Debug.js:169 [49495][ProtectionController] DRM: KeySystem Access Granted for system string (com.widevine.alpha)! Selecting key system...
Debug.js:169 [49498][PlaybackController] Requesting seek to time: 1743449990.8983333 (internal)
```
##### Expected behavior
Using dash.js v4.7.2 and the same DASH manifest, trigering the 400 scte35 events is quick and was expecting the same behavior with dash.js v5.
##### Identified root cause
Related to fix made here [48a2bf5](https://github.com/Dash-Industry-Forum/dash.js/pull/4661/commits/48a2bf5214b0a0df3fe3c53e4d4b4113c5b5bf84).
Especially the usage of '{ event: JSON.parse(JSON.stringify(event)) }' for event object cloning instead of just sharing a reference '{ event: event }'Opened by da-gr—15 hours ago
fix Settings sanitizer for initialTrackSelection based on idthis implements proposed changes from https://github.com/Dash-Industry-Forum/dash.js/issues/4737
additionally it adds two unit tests for MediaController and id-based initial track selectionOpened by stschr—2 days ago
MediaController.setInitialMediaSettingForType() cannot filter on IdIt seems that it should be possible to specify the track id explicitly like this:
```
player.setInitialMediaSettingsFor('audio', { id: 'audio-und-mp4a' })
```
and the code in MediaController.setInitialMediaSettingForType() has the following line:
```
filteredTracks = filterTracksBySettings(filteredTracks, matchSettingsId, settings)
```
However, it's not possible to specify an initial setting because the id is filtered out in MediaPlayer._sanitizeSettings()
Sample file is here: https://content.media24.link/Dune2/manifest.mpd
Patch is simple.
```
--- a/src/streaming/MediaPlayer.js
+++ b/src/streaming/MediaPlayer.js
@@ -2725,6 +2725,9 @@ function MediaPlayer() {
return null;
}
+ if (value.id) {
+ output.id = value.id;
+ }
if (value.lang) {
output.lang = value.lang;
}
```Opened by gmcgarry—3 days ago
