Bringing it all together

For the grand finale, we will bring everything together: an example with languages, fallback, immersive audio, and accessibility.

We will prepare a manifest file that includes several languages and codecs, immersive audio, and an accessible presentation with AudioDescription.

Table 1. Adaptation Sets. View the full manifest file.
#	Codec	Language	selection priority	channel configuration	role	accessibility	notes
1	AAC	English	96	stereo	main
2	Dolby Digital Plus	English	97	5.1	main
3	Dolby Digital Plus	English	99	immersive	main
4	Dolby AC-4	English	98	5.1	main
5	Dolby AC-4	English	100	immersive	main
6	Dolby Digital Plus	Spanish	95	5.1	main
7	Dolby Digital Plus	English	94	stereo	alternate	description	VDS

The selection rules above can be implemented with the rules laid down in the DASH-IF guidelines, clause 3.9.4.

To let dash.js know these selection rules should be applied, use the setInitialMediaSettingsFor() method.

Let's run through these rules to illustrate how this works.

low-end device: This device only supports AAC, and no other codec. The very first step removes all AdaptationSets except #1, which will subsequently be selected and played.
Dolby Atmos TV, English language preferred: This device supports Dolby Atmos in Dolby Digital. The AdaptationSets referencing Dolby AC-4 assets are removed. Of the remaining assets, #3 has the highest priority and is selected and played.