See also: IRC log
Daniel: We had a 2 day developer
meetup, looking at the TV API
... from a Hybridcast and TV API point of view
... We looked at things in Hybridcast not supported by the TV
API
... Firstly, the triggered interactive overlay. Could this be
split into two requirements: a trigger requirement, and an
overlay requirement
... There could be two kinds of triggers, one with a
pre-defined time, and one that is generated live
... For those with pre-defined times, could the in-band
resource track spec be used?
<ddavis> http://www.w3.org/2014/05/28-webtv-minutes.html#item05
Bin: There can be relative time
stamps encoded in the stream for triggering events
... The service provider can signal events, say every 10
minutes
Paul: There is also an alarm clock API
Daniel: Can out of band triggers be supported by server sent events?
<ddavis> https://www.w3.org/community/tvapi/wiki/Main_Page/Requirements_Mapping
Daniel: Hybridcast does not have a channel change event, as the application is closed on changing channel
Paul: Hybridcast and HbbTV are
essentially channel-bound, so changing channel discards the
interactive environment, to be replaced with a new one.
... With the Open IPTV Forum specs, the application persists,
this is described in the application lifecycle model in the
DAE
Daniel: The group was wondering whether the TV control API should converge these two approaches
Paul: The issue of a security model was raised on the mailing list, and there are privacy concerns too.
Daniel: We discussed using watermark fingerprint triggers for synchronising alternate streams.
Bin: With the supplemental
triggers, these are optional, if present they should be
surfaced by the API
... We would have to define the content type and data
structures for these triggers, to identify these as trigger
metadata
... Some fields are mandatory, such those controlling the as
start time and end time/duration of the trigger
<ddavis> Type: video/x-iptvf-broadcast
Daniel: It would help to write down more of this detail in the requirements
<ddavis> <param name="video" value="arib://<original_network_id>.<transport_stream_id>.<service_id>[;<content_id>] [.<event_id>]/<component_tag>[;<channel_id>]">
<ddavis> http://www.w3.org/TR/mediacapture-streams/#idl-def-MediaStream
Daniel: Regarding integration with HTML5 audio and video elements, Hybridcast a specific content-type, with parameters not available in the media stream
Paul: There is also a different
state machine, when comparing HTML5 media with OIPF
... Looking at combining the W3C specs, we've found pausing
live TV in a media element would require reinitialising the
media element
... Chris suggested maybe allowing buffering with MediaStreams,
but do we define that or put this to that group
Daniel: Emergency notifications are implemented by a separate system, EWS, not within Hybridcast
<aldafu> Zakim: aacc is me
Daniel: There is an earthquake prediction service, which may need to be triggered differently
Paul: In the US there is a classification, different alerts have different priorities
Daniel: Regarding the EPG, we
have a getProgrammes method in the mapping table, which takes
an options object
... our API should allow more filtering options, such as by
type of content (movies, sport)
... also, get EPG by channel
... the duration option is confusing, as its the time range for
the search, maybe we should change this to endTime?
Paul: There are lots of ways to search, so with TV Anytime, we have attribute pairings, more schema-less to allow more flexible data models
Daniel: The general view was to allow more ways to search for programmes
<ddavis> https://w3c.github.io/tvapi/spec/#h-tvprogram-interface
Daniel: The TVProgram interface,
should there be both a short description and a long
description, is it a satellite or terrestrial programme.
... The getAudioLanguages and getSubtitleLanguages methods were
felt to be too restrictive. There can be alternate commentaries
but in the same language.
... An API like getAudioTracks might be more flexible, similar
for subtitles: getSubtitleTracks
... The satellite/terrestrial could be added to the
TVChannelType enum
... The isFree flag on the TVChannel could be added to the
TVProgramme object, for free channels that contain some paid
programmes
... Regarding parental control, this could be done at the
programme or at the system level, we may need to clarify our
requirements
... We'll share our notes from the meeting
Paul: Did the group identify anything missing?
Daniel: Maybe more device information, with properties such as manufacturer, but we need to identify requirements.
Bin: Which group is working on the in band tracks?
<ddavis> https://www.w3.org/community/inbandtracks/
<ddavis> http://dev.w3.org/html5/html-sourcing-inband-tracks/
Paul: This is looking at mappings from ISDB, ATSC etc to tracks associated with a video element
Bin: I have an interest in the
encoding mechanism, for example, a raw A/V stream from the
studio, how do we add the triggers and encode them within the
stream. Which is the easiest way to do this during
encoding?
... The dataCue can provide an abstraction over the underlying
transport method
Paul: HbbTV defines stream events. There's a method addStreamEventListener. How it's encoded in the transport stream would be specified by DVB
Daniel: One other comment, more
for the multi device timing comnunity group: HTML5 needs a more
accurate way to reference the timeline, e.g., for ad insertion.
for example, the timeupdate event is only generated every
250ms
... That's all our feedback, we had a good useful discussion
today.
<Bin_Hu> http://www.w3.org/community/tvapi/track/actions/open
<ddavis> ACTION: ddavis to share wiki page containing feedback from Japan TV dev meetup [recorded in http://www.w3.org/2015/03/17-tvapi-minutes.html#action01]
<trackbot> Created ACTION-28 - Share wiki page containing feedback from japan tv dev meetup [on Daniel Davis - due 2015-03-24].
Alex: with action 23, the feedback and discussion about action 24 is related to this, in particular the background task for recording
Bin: So we can close action
23
... Paul and Chris have reported their findings for actions 24
and 25, on recording and timeshifting
<kaz> action-23?
<trackbot> action-23 -- Alexander Futász to Email the mailing list regarding the recording.series requirement and proposed solutions -- due 2015-02-24 -- CLOSED
<trackbot> http://www.w3.org/community/tvapi/track/actions/23
<kaz> action-24?
<trackbot> action-24 -- Paul Higgs to Look at the media capture and streams api and compare against our recording and timeshifting requirements -- due 2015-04-14 -- OPEN
<trackbot> http://www.w3.org/community/tvapi/track/actions/24
<kaz> action-25?
<trackbot> action-25 -- Chris Needham to Look at the timeshifting requirements and the html video element -- due 2015-03-17 -- OPEN
<trackbot> http://www.w3.org/community/tvapi/track/actions/25
Paul: We need to ensure our API
meets regulatory requirements regarding background workers, as
TV devices go into standby mode
... It would be useful to see some examples of how the various
APIs fit together
<Paul_Higgs> what I call the alarm clock API is http://www.w3.org/2012/sysapps/web-alarms/
<Paul_Higgs> sorry, I have a hard stop now - I think this call is just scheduled for 1 hour!
Bin: For action 25 (time shifting), we can do some more investigation, look again at our requirements, also we should understand the rationale for preventing buffering of MediaStreams. We should do this before proposing any changes.
<scribe> ACTION: Chris to look further into timeshifting and MediaStream API rationale [recorded in http://www.w3.org/2015/03/17-tvapi-minutes.html#action02]
<trackbot> Created ACTION-29 - Look further into timeshifting and mediastream api rationale [on Chris Needham - due 2015-03-24].
Bin: we'll leave actions 26 and 27 open, and hopefully report on these next time
<kaz> action-26?
<trackbot> action-26 -- Bin Hu to Contact sean and add emergency alert requirements to the spec -- due 2015-02-24 -- OPEN
<trackbot> http://www.w3.org/community/tvapi/track/actions/26
<kaz> action-27?
<trackbot> action-27 -- Bin Hu to Work on triggered interactive overlay requirements -- due 2015-02-24 -- OPEN
<trackbot> http://www.w3.org/community/tvapi/track/actions/27
<kaz> [ adjourned ]