Dash.js: Stream quality not changing immediately

[redd29]

Environment

• [x] The MPD passes the DASH-IF Conformance Tool on https://conformance.dashif.org/
• [x] The stream has correct Access-Control-Allow-Origin headers (CORS)
• [x] 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

• Dash.js version: v3.2.1
• Browser name/version: Chrome 89.0.4389.90
• OS name/version: Ubuntu 20.04

Steps to reproduce

1. Start playing the video
2. Change the stream quality
3. It wont change immediately

Observed behavior

On quality change, it is not reflected immediately.

Expected behavior

The quality should change and it should continue to play in that quality immediately

This is how Im changing the quality

let firstLoad = true;
      const dash = Dash.MediaPlayer().create();
      dash.on("manifestLoaded", (e) => {
        const _qualityLevels = (e.data as any).Period.AdaptationSet[0]
          .Representation;

        const qualityLevels = _qualityLevels.map((l: any) => l.height) as any[];

        options.quality = {
          default: qualityLevels[0],
          options: qualityLevels,
          forced: true,

          onChange: function (quality: number) {
            if (!firstLoad) {
              const t = qualityLevels.findIndex((q) => q === quality);
              console.log(t);
              dash.setQualityFor("video", t);
            }
            firstLoad = false;
          },
        };
        plyr = new Plyr(element!, options);
      });

      dash.initialize(element!, decodedUrl, true);

[dsilhavy]

Try enabling fastSwitch:

player.updateSettings({streaming: {fastSwitchEnabled: true}})

• @property {boolean} [fastSwitchEnabled=false]
  
  
  
  • When enabled, after an ABR up-switch in quality, instead of requesting and appending the next fragment at the end of the current buffer range it is requested and appended closer to the current time.
  
  
  • When enabled, The maximum time to render a higher quality is current time + (1.5 * fragment duration).
  
  
  • Note, When ABR down-switch is detected, we appended the lower quality at the end of the buffer range to preserve the
    
    higher quality media for as long as possible.
  
  
  • If enabled, it should be noted there are a few cases when the client will not replace inside buffer range but rather just append at the end.
    
    
    
    
    
    • 
      
      
      
      1. When the buffer level is less than one fragment duration.
      
      
      
      
    
    
    
    • 
      
      
      
      1. The client is in an Abandonment State due to recent fragment abandonment event.
      
      
      
      
    
    
    
  
  

[redd29]

Ok now im seeing that the quality doesnt set to what i set, it automatically bumps it

[dsilhavy]

Try to disable ABR if you dont want to automatically adjust the quality after a change:

const cfg = {streaming: {abr: {autoSwitchBitrate: {video: false}}}}
self.player.updateSettings(cfg);
self.player.setQualityFor('video', item.index - 1);

[redd29]

Yes that is definitely what I was missing. Thanks!