[foms] Text of ISO/IEC DIS 23001-6 Dynamic Adaptive Streaming over HTTP

[Silvia Pfeiffer]

On Thu, Feb 17, 2011 at 11:56 AM, Mark Watson <watsonm at netflix.com> wrote:
>
>> On Feb 16, 2011, at 4:14 PM, Silvia Pfeiffer wrote:
>>
>> I agree - I think we need profiles of DASH - in particular a
>> restriction to just one mime type being used in a file that should go
>> into a @src attribute of <video>, <audio> or <source>. Also, we'd need
>> to make sure it works with the @media query attribute of <source>
>> elements, thus targets particular device features.
>
> I think the requirement should be that it must be possible to determine
> whether a manifest can be played without loading the manifest.


That's indeed concretely what the @type and @media attributes are used for.


>> What I most wonder about is, if such a DASH file was to be used in
>> place of a media resource in the @src attribute of a <video>, <audio>,
>> or <source> element, what will its mime type be? It would make life
>> easy if the mime type could just be the mime type of the resource that
>> it stands for, e.g. when all referenced files are webm, the mime type
>> of the manifest file should be video/webm. Unfortunately, it is
>> proposed to be video/vnd.mpeg.dash.mpd which doesn't help the browser
>> in deciding whether it will support the resource type therein. Maybe
>> we could create a profile and then have something like video/dash+webm
>> and video/dash+mp4 as mime types which is much more informative.
>
> They defined a "profiles" parameter to this MIME type which can be used to
> say which profile or profiles the manifest is compliant to.
> So, if someone defines a profile which goes as far as specifying
> mp4+H.264+aac (say) and someone else goes defines a profile which specifies
> WebM+VP8+Vorbis, then it is possible to specify which one a manifest is
> compliant to. Or indeed that it is compliant to both, meaning that it can be
> played so long as you support one profile or the other.

That sounds great. Maybe that's the best way to go.

Silvia.


> ...Mark
>
> Cheers,
> Silvia.
>
>
> On Wed, Feb 16, 2011 at 2:39 AM, Jeroen Wijering
> <jeroen at longtailvideo.com> wrote:
>
> Hello all,
>
> I wanted to forward a couple of updates on the WebTV workshop. They've been
> two interesting days, especially on the adaptive streaming / content
> security front.  We had a session on both adaptive streaming (focussing on
> DASH) and on content protection (focussing on PIFF). Sheets of the
> presentations done at both sessions can be downloaded here:
>
> http://www.w3.org/2010/11/web-and-tv/agenda.html
>
>
> On the DASH side, the spec has just been released. Silvia has forwarded a
> download link already (see below). In short, it's a flexible XML format that
> seems to support all required use cases (fragments, range-requests, manifest
> polling, etc). Outstanding issues are:
>
> *) Licensing. What happens here is not entirely clear. At their
> presentation, Microsoft committed to make available any patents in this area
> they have under the MPEG RAND license. The W3C is still going after other
> contributors to the spec, to see if they want to take similar steps.
>
> *) Profiling. Since the system is quite flexible, it is possible to define
> profiles for DASH. Profiles can contain both limitations to the XML elements
> / attributes and the format of media files referenced in the XML. A "basic
> ondemand" profile is defined; there'l probably be a "basic-live" profile as
> well.
>
> I attached example DASH files that use WebM to define both an ondemand and
> live stream. The ondemand one uses range requests to pull both the Cues and
> fragments. The live one uses reloading of the manifest (like Apple does), a
> URL template (so a full fragment list is not needed) and separate codec
> setup segments (so they're not constantly duped - I understand setup in
> Vorbis is quite big). They should give a rough idea of how an ondemand or
> live stream can be defined with a DASH manifest.
>
>
> On the content protection side, there was some talking about PIFF -
> Microsoft's encrypted, fragmented MP4 format. Interesting about this is the
> clear separation of encryption/decryption and the rights management layer.
> All presenters backed this approach. Perhaps this is interesting for open
> video / WebM as well, since encryption can be very useful for e.g. basic
> content protection (no DRM, just keys) or privacy reasons.  Any real
> standardization seems a bit further away though. There's been no detailed
> proposal on how this decryption / key signalling could work in HTML5
> (cross-browser and cross-codec).
>
>
> Steve Lhomme, JB Kempf and Mark Watson were also there; please chime in if I
> missed anything interesting.
>
>
> Kind regards,
>
> Jeroen
>
>
>
>
>
> On Feb 13, 2011, at 1:02 PM, Silvia Pfeiffer wrote:
>
> FYI: MPEG have released their draft DASH standard for adaptive HTTP
> streaming.
>
> Plus there is a group forming in the W3C about Web & TV, which is also
>
> interested in the topic and looking at DASH with lots of interest.
>
> Cheers,
>
> Silvia.
>
>
> ---------- Forwarded message ----------
>
> From: Thomas Stockhammer <stockhammer at nomor.de>
>
> Date: Sat, Feb 12, 2011 at 6:14 AM
>
> Subject: [W3C Web & TV] Text of ISO/IEC DIS 23001-6 Dynamic Adaptive
>
> Streaming over HTTP
>
> To: public-web-and-tv at w3.org
>
>
> Experts,
>
> it was pleasure to meet you all.
>
> I wanted to make you aware that the
>
> Text of ISO/IEC DIS 23001-6 Dynamic Adaptive Streaming over HTTP
>
> is now available here
>
> http://mpeg.chiariglione.org/working_documents/mpeg-b/dash/dash-dis..zip
>
> Note that this is a draft standard.
>
> Best regards
>
> Thomas
>
>
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