Flexible Insertion of URL Parameters

Annex I of the MPEG-DASH specification defines how to configure URL parameters of media segment URLs in a similar fashion to the URL template mechanism. This mechanism allows an “inheritance” from MPD URL parameters when the MPD is delivered over HTTP, i.e. extraction of one or more key-value pairs from the query string of the URL used to fetch MPD.

Example procedure

In an easy example the initial request URL to the MPD looks like this https://livesim.dashif.org/livesim2/annexI_dashjs=rocks/testpic_6s/Manifest.mpd?dashjs=rocks. The link to the MPD contains a query parameter with the key dashjs and the corresponding value set to rocks.

The AdaptationSet of type video in the MPD has an additional EssentialProperty:

<EssentialProperty schemeIdUri="urn:mpeg:dash:urlparam:2014">
    <up:UrlQueryInfo xmlns:up="urn:mpeg:dash:schema:urlparam:2014" queryTemplate="$querypart$"
                     useMPDUrlQuery="true"></up:UrlQueryInfo>
</EssentialProperty>

This configuration in the MPD tells dash.js to use the query parameters from the MPD URL for the media segment URLs. As a consequence, the outgoing requests to video segments will look like this:

https://livesim.dashif.org/livesim2/annexI_dashjs=rocks/testpic_6s/V300/289578461.m4s?dashjs=rocks. dash.js is automatically appending the query string dashjs=rocks to the media segment request.

Example implementation

An example of flexible insertion of URL parameters can be found in the sample section.