Re: [tvcontrol-api] Why retrieve a list of tuners instead of just one tuner?

I understand Igarashi-san's point, and there are differences between 
the models used for retail TVs and for subsidized STBs.

My view on the issue of constraints is that constraints should work 
across all sources. The case where a device may only be able to 
support a certain number of concurrent streams, or may have limited 
ability to support multiple source types at the same time, for 
whatever reason, is one that needs to be supported.  There will be 
differences between platforms that mean these capabilities and 
constraints will be different, but I think that the constraints 
mechanism is flexible enough to deal with this.

For me, the problem with having the channel lists on the sources is 
this: if the device UI manages the channel list, and has an option to 
show the user a merged channel list, an app can't create a merged 
channel list that matches the one the device UI will show (because the
 user may have re-ordered the channel list in the device UI, for 
instance).  Unless there is an API for getting the channel list on the
 TVManager object, I don't see a way to solve this.

I see a couple of possible solutions for dealing with the case where 
sources can't be handled seamlessly - whether for technical or 
business reasons.  

One option is to simply say that when the user selects which source 
they want, this is done *outside* the scope of the TV control API.  An
 app will then see only those sources which the user has currently 
selected: for instance, if the user has selected the DVB-S source, 
then in the set of capabilities an app will only see DVB-S as a 
supported source type.  Similarly, when the app calls 
TVManager.getChannelList(), it only gets a list of the channels 
available over DVB-S.

The second approach is for TVManager.getChannelList() to take a set of
 constraints as a parameter, where those constraints specify which 
source (or set of sources) should be included in the returned channel 
list.  An implementation can then return an appropriate response if 
the app requests channels from a set of sources that can't be handled 
seamlessly. 

Both of these approaches let us solve the problem without needing 
getChannelList() methods in different places to handle the two use 
cases: the question then becomes, in the case where sources can;'t be 
handled seamlessly, does the user agent need to be aware of this, or 
is that selection outside the scope of the user agent?

Steve.

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Received on Friday, 27 January 2017 15:18:29 UTC