On 01/27/2017 09:04 PM, Martin Storsjö wrote: > On Fri, 27 Jan 2017, Peter Große wrote: > >> On Fri, 27 Jan 2017 14:58:21 +0200 (EET) >> Martin Storsjö <[email protected]> wrote: >> >>> On Fri, 27 Jan 2017, Peter Große wrote: >>> >>>> See >>>> http://vm2.dashif.org/dash.js/docs/jsdocs/MediaPlayer.html#addUTCTimingSource >>>> for more information. Usable default: "https://time.akamai.com/?iso"; >>> >>> Hmm, I don't see this documented in ISO/IEC 23009-1:2014 at least, and the >>> documentation from dashif don't seem to define it either. >>> >>> I won't mind including it, but I'd like to know what standard defines it >>> before merging. >> >> Mh true, this is not part of the standard, but introduced in their >> "Guidelines >> for Implementations: DASH-IF Interoperability Points" [1] in Section 4.7. >> >> Which URL shall I reference in the commit message? The guidelines link page, >> the PDF, or not at all but mentioning the document's title? > > I'd at least refer to the guidelines page, but linking explicitly to the PDF > as well probably is good. > >> The "usable default" is just a hint. It is not mentioned in any document, it >> was >> just what I found in player implementations (like mentioned in the message >> above). I could drop it. > > No, do keep it, any such extra info is useful. > > But I started wondering, is there any actual use for this, when we explicitly > list all the segments (either as individual segment filenames or via the > template). As far as I can see, this is mostly necessary if you implicitly > calculate the live edge based on availabilityStartTime and the segment > length. So is there actually any gain from using it in our configuration?
Yes, because the players will always try to calculate the live-edge, as they don't know whether the segment they are requesting is available yet. They can't trust the browsers localtime and they don't know whether the availabilityStartTime is ok for synchronization. That's also why Shaka-player now gives a warning if there is no UTCTiming tag present in live-manifests. https://github.com/google/shaka-player/commit/1fb78929c1551a3e4f1a07323ce67ee622503273 Best, Anton _______________________________________________ libav-devel mailing list [email protected] https://lists.libav.org/mailman/listinfo/libav-devel
