- From: Cyril Concolato <cyril.concolato@telecom-paristech.fr>
- Date: Sun, 02 Nov 2014 17:42:39 +0100
- To: Bob Lund <B.Lund@CableLabs.com>, Silvia Pfeiffer <silviapfeiffer1@gmail.com>
- CC: "Abello, Jean-Pierre" <Jeanpierre.Abello@nielsen.com>, "public-inbandtracks@w3.org" <public-inbandtracks@w3.org>, Eric Carlson <eric.carlson@apple.com>
Hi Bob, Silvia, Le 02/11/2014 16:57, Bob Lund a écrit : > > On 11/2/14, 3:45 AM, "Silvia Pfeiffer" <silviapfeiffer1@gmail.com> wrote: > >> On Wed, Oct 29, 2014 at 8:48 AM, Cyril Concolato >> <cyril.concolato@telecom-paristech.fr> wrote: >>> Yes, I do think HLS is another format that we should target. It has some >>> commonalities with existing formats that we target: DASH for the use of >>> manifests and adaptative streaming aspects; and MPEG-2 TS as a segment >>> format. The basics of exposing tracks from TS should be reusable. It >>> might >>> need some tweaking compared to what we started specifying, for instance >>> to >>> expose ID3 Tag PES streams. In an informal discussion with Eric (in >>> copy), I >>> discovered that WebKit already exposes them using some API, see: >>> >>> http://trac.webkit.org/browser/trunk/LayoutTests/http/tests/media/track-i >>> n-band-hls-metadata.html >> For the record: I do have some reservations about adding DASH and HLS >> support, since browsers do not typically support these formats >> natively. [CC] I've heard that Webkit/GTK has some native support for DASH, but I couldn't verify it. I would expect that in the future some browsers have native support for DASH or HLS. But I agree with you that support for DASH/HLS is different from direct support for TS/MP4/OGG... >> Actually, HLS is supported in Safari, so it has some excuse, >> but DASH is only supported via Media Source Extensions. I have been >> worried about that a bit. > There has been text added to the spec for DASH using MSE. MSE behavior is > that the UA sources tracks based on information in Initialization > Segments. The application may specify default track attributes for those > tracks, which the UA will use if those same attributes are not sourced > from Initialization Segment data. It seems useful to me for the sourcing > spec to describe this. > > On a related note, I plan to submit an MSE bug so that it references the > sourcing spec for sourcing tracks as described above. What about adding a diagram like this one to the introduction: http://concolato.wp.mines-telecom.fr/files/2014/11/inband-sourcing.png and maybe indicating that some implementations may use one path or the other. Cyril > >> I think these facts probably need to be explained better in the >> document. This is particularly important, since different target >> audiences are addressed with the different formats: DASH and HLS >> address Web Developers (+Safari), MPEG-4, WebM and Ogg address Browser >> developers, and MPEG-2 addresses Web-enabled set-top box vendors >> (these are still UA devs). So, DASH and HLS are bascially in a league >> of their own and should probably be moved to an appendix or so. >> >> Silvia. >> >> >> >>>> Do you have a recommendation on how to best add this to the draft? >>> One way would be to file a bug on the current draft, with or without a >>> Git >>> Pull Request proposing additional/modified spec text. >>> >>> Best regards, >>> >>> Cyril >>> >>> -- >>> Cyril Concolato >>> Multimedia Group / Telecom ParisTech >>> http://concolato.wp.mines-telecom.fr/ >>> @cconcolato >>> >>> -- Cyril Concolato Multimedia Group / Telecom ParisTech http://concolato.wp.mines-telecom.fr/ @cconcolato
Received on Sunday, 2 November 2014 16:43:08 UTC