- From: Matt Hammond <matt.hammond@rd.bbc.co.uk>
- Date: Thu, 07 Apr 2011 09:51:49 +0100
- To: public-web-and-tv@w3.org, "Olivier Carmona" <ocarmona@awox.com>, "Russell Berkoff" <r.berkoff@sisa.samsung.com>
- Cc: "Giuseppe Pascale" <giuseppep@opera.com>
Hi Russell, Your description matches my understanding of DLNA/UPnP - which is useful confirmation for me - many thanks! I agree that this model works well for streaming between home devices. But it makes the assumption that all content is streamable between home devices. A TV or set-top-box that can receive broadcast or IP delivered TV or radio does not necessarily match this. In order to be able to implement some of the second-screen scenarios presented at the last workshop, I would hope that APIs for home networking are also able to query and control TV functions such as changing channel or retrieving broadcast programme metadata. This is why I am interested in APIs that can support both in (if possible) a single simple unified way. The approach we took at the BBC with our Universal Control (UC) API is one possible way to achieve this. If a TV implementing UC API needed to be able to discover and stream content on other devices in the home then it would almost certainly use DLNA/UPnP or other similar technologies to do this, but the client/controller device does not need to know the difference. From the perspective of a client of the UC API implementing TV, streamed content is discoverable and selectable for playback in the same way as a television channel or programme would be. regards Matt On Thu, 07 Apr 2011 08:39:18 +0100, Russell Berkoff <r.berkoff@sisa.samsung.com> wrote: > Hi Matt, > > > Let me try to answer "frame" your question/observation and hopefully > provide some brief answers: > > > Q1: Does DLNA/UPnP distinguish between the description of content, i.e. > metadata describing content (title, description, available media > formats) and the device actually supplying the content? > > > Q2: Does DLNA/UPnP allow metadata and content to reside on separate > devices on the home network? > > > Q3: Does DLNA/UPnP allow the remote commanding of playback devices? > > > > A1: Yes...DLNA/UPnP has a distinct metadata service (ContentDirectory > Service). The metadata provided by this service can refer to content > elsewhere on the home network. > > > A2: Yes > > > A3: Yes...UPnP/DLNA allows remote commanding of playback devices. A > Digital Media Controller can obtain descriptive content metadata and > tell a playback device to "pull" a piece of content from a distinct > "content source" on the home network. > > > The Digital Media Controller in this scenario would examine the metadata > from both the Playback Device (Digital Media Renderer) and from the > metadata service (Digital Media Server - ContentDirectory Service) and > insure a media format is chosen that both the Content Source can provide > and the Playback Device can render. Once a match is found the Digital > Media Controller, would command the Playback device to fetch the content > from the Content Source. > > > Regards, > > Russell Berkoff > > Samsung Electronics > > > > > -----Original Message----- > From: Matt Hammond [mailto:matt.hammond@rd.bbc.co.uk] > Sent: Wednesday, April 06, 2011 5:03 AM > To: public-web-and-tv@w3.org; Olivier Carmona > Cc: Russell Berkoff; Giuseppe Pascale > Subject: Re: [HOME_NETWORK_TF] Home Network Technologies > > > Hi Olivier, > > > On Wed, 06 Apr 2011 12:22:38 +0100, Olivier Carmona <ocarmona@awox.com> > > wrote: > > >> > >> Hi Matt, > >> > >> DLNA 1.0 is about two-box pull model: on one side you have a Digital > >> Media Player (a client in your description) and on the other side you > >> have a Digital Media Server (a rendering device in your description). > >> DMP discovers and then browses DMS, and can request one of the browsed > >> items to be played. The only difference with your model is that this the > >> DMP that based on the information exposed by the DMS, decides wherever > >> it can play the content. > > > My explanation was not as clear as it should have been - please accept my > > apologies for that. The client that I described does not display media > and > > does not send or receive media streams. It is the server that will > > render/display media, and it is up to the server to work out what media > is > > available to it and to arrange to stream (or otherwise obtain) it. This > > aspect would be completely opaque to this client. The server/renderer > > could well use DLNA to discover and stream that content from a 3rd > device, > > but the client would not be aware of this. > > > For me, the attraction of this model is that it is more abstract that > just > > streaming and can easily subsume access to local storage but also access > > to services such as live television broadcast. A television programme is > > just another item of content that the server reports it has available to > > it, and which the client can ask it to display. > > > > > regards > > > > Matt > -- | Matt Hammond | Research Engineer, BBC R&D, Centre House, London | http://www.bbc.co.uk/rd/
Received on Thursday, 7 April 2011 08:52:46 UTC