[linux-dvb] [RFC] Should a DVB frontend report the board name?

CityK CityK at rogers.com
Thu Feb 8 07:53:34 CET 2007


Hi Manu,

Manu Abraham wrote:
> ..snip..
>
> So the concept of a frontend /nim/dc receiver are all names which are
> used in different contexts for different categories of devices. But it
> is quite hard to draw a distinct line, in such a case. It could be
> argued either ways.  (Just like painting the bikeshed green) 

True enough.


>>
>> > frontend = demod name (that's what we have currently),
>>
>> And that would technically be wrong ... although if it works into the
>> coding framework, then so be it.
>>
>> > Tuner is unimportant in this case as it doesn't have much of ops.
>>
>> I'm not certain what you mean by "ops", but I gather that its minor role
>> is what has lead to the project's definition of frontend to equal demod
>>
>
> The project has never stated that at any place. Or is there ?

Not that I know of -- I was just surmising that by what you wrote i.e.
"frontend = demod name (that's what we have currently)"


> But i don't understand what your argument is -- for example when i
> have a "tuner module" (tin can inclusive of the demod) say one based
> on a STV0299, what advantage do you get by telling the user that it
> uses a TSA5059 PLL in the RF stage ?

My point, as I mentioned I at the very beginning, wasn't related to the
central premise. 

I  understand that your argument in the discussion proper is: give the
component name in it's own relevant place and not in the frontend code.

What I had interjected was a sidebar, based largely upon your words of
"frontend = demod name (that's what we have currently)".  I thought it
might be prudent to address this secondary point.  In particular, it
sounded like the project's definition of what constituted a frontend was
a little constrained or limited in scope.  I thought perhaps some
discussion was warranted.  I'm satisfied by your explanation.

>> Lastly, as some food for thought -- we're already starting to see the
>> move towards multi-purpose IC's.  Examples:
>> - Xceive 3028 tuner and analog demod;
>> - ATI theater 650 analog demod, A/V decoder & mpeg encoder.
>> It likely will be a few years yet, but pretty soon we WILL run into the
>> case where the traditional frontend and "backend" components on the DTV
>> devices merge into one IC.  How then does one define the abstraction?
>
> even though the entire thing is in one chip, it is an abstraction, so
> it doesn't matter whether the MPEG decoder and the demodulator are on
> the same chip. Still they are separate functional blocks requiring
> separate control (You can't ask a MPEG decoder to do some job on a RF
> signal)
>
>> At that point, the concept will only refer to the relevant processing
>> stages carried out in that single IC.
>
> IC  = Integrated Circuit. Integration doesn't mean that you loose
> control. Of course noise is added into the system. The greater the
> integration the greater the noise, in a constant environment.

Yes, I agree of course.   But I think you missed what I was driving at. 
This section, which wasn't expressed well, was also related to my
sidebar point, and not to the discussion proper -- specifically, I was
directing commentary as to what a frontend should be defined as, and how
it should be treated.

>> Will this solution account for a single, multifunctional IC, as I have
>> just described?
>
> Why not ? look at the MB86A15/16 (tuner + demod in a single chip in
> that sense)

Okay.

In case it wasn't clear (and it really wasn't :) ! ) I had switched
gears here and was expressing concern, just as Hartmut and a few others
had, in regards to "naming conventions which are useful for the average
user".  As I said, I completely understand your argument: give the
component name in it's own relevant place and not in the frontend code. 
But as I also prefaced at the start of the message, I don't think
everyone was on the same page.  I believe that the other prevailing
point of contention was not so much as to whether having the demod name
listed in the frontend output, but rather whether information relevant
to the average user is being conveyed as a whole.

My hypothetical example of a multifunctional, single IC was meant to
exemplify this point .... although I think I trailed off with my train
of thought.  Anyway, not to worry.

Cheers

 







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