Set an expectation that chained/fallback MPDs operate correctly in self-reference scenarios

[sandersaares]

I believe there is a CR in progress that defines the interoperability guidelines for MPD chaining and fallback. I would like to outline a specific scenario of interest that I feel should be explicitly called out as supported as part of this feature: self-referencing for fallback or chaining.

The scenario of interest is one where an MPD loaded from https://example.com/a.mpd is allowed to reference itself as the fallback or chained-to MPD. This enables the following useful scenarios:

• MPD-controlled endlessly looping playback of the same content.
• Server-controlled basic playlist features via HTTP redirect (after finishing MPD playback, the next request for the same MPD URL might result in an HTTP redirect to a different MPD).

While nothing in the current chaining CR seems to contradict this usage, I would like it to be explicitly stated as supported, to help avoid accidental implementation errors in players due to implicit assumptions that the URL will be different.

[acbegen]

Hi Sander

This looks good to me. Could you update the CR accordingly?

[sandersaares]

Hey Ali. I am not very familiar with the CR or its history, so it might take me some time to understand the proper modification to apply. Most likely someone more familiar with the CR would achieve a better result. My perspective here is purely as that of a consumer of the result and I have not a good overview of the reasoning that brought about the CR.

If I get some moments to deal with it, I will try to perform the edit in question. It may prove impractical to find the time, though.

[acbegen]

Uploaded CR-MPD-Chaining-DASH-IF-IOP-v4.0-r4 to reflect the suggested text.