[PATCH] Re: [linux-dvb] [PATCH] Multi protocol support (stage #1)

Manu Abraham abraham.manu at gmail.com
Mon May 22 16:43:11 CEST 2006

Johannes Stezenbach wrote:
> On Mon, May 22, 2006, Manu Abraham wrote:
>> Johannes Stezenbach wrote:
>>> Anyway, one last try. Let's go back to the very beginning:
>>> - we need to extend frontend API for DVB-S2, DVB-H etc.
>>> - we cannot do so without breaking backward compatibility
>>>  because of mistakes made when defining the current API
>>> - so now that we define new API, we don't want to repeat
>>>  the same mistake, but design in a way that make future
>>>  extensions possible without too much pain for
>>>  driver and application developers
>>> - right from the beginning my position was to do the
>>>  *minimal* work necessary to support the *current*
>>>  requirements -- keep it simple and stupid
>>> - and add other stuff later when the need arises
>>> - and all along you totally ignored this and instead
>>>  want to cram every last detail into the API that
>>>  you think *might* be necessary
>>> - wrt requirements: you need to think through how
>>>  an application will work (how does dvbscan discover
>>>  DVB-S2 transmission? where do the tuning parameters
>>>  come from?)
>> currently the tuning parameters come from the 
>> s2_satellite_delivery_system_descriptor
>> what i have in there is the sis-mis flag and the transport stream 
>> identifier to select the streams
> Anyone seen a s2_satellite_delivery_system_descriptor in any broadcast?
> There are DVB-S2 braodcasts on Astra 19.2E, do they have
> s2_satellite_delivery_system_descriptors?

Well on Arabsat some of the broadcasters does name all the providers as 
So should i say that the current usage too is wrong ?

>>> Remember: You cannot remove anything from the API
>>> once it is in there. But you can always add stuff later.
>>> Please ask yourself who are doing this API design for, and
>>> how people are going to benefit from your work.
>>> IMHO:
>>> - users just expect to be able to buy a DVB-S2 card and
>>>  watch the services broadcast *today* via DVB-S2
>>> - application developers want to support DVB-S2 with
>>>  as little hassle as possible
>>> With the new API "as little hassle as possible" for
>>> apps already means:
>>> - testing for support for the new API
>>> - fallback to using the old API for backwards compatibility
>>> :-(
>>> IMHO it is of no use to further complicate the matter by
>>> adding lots of unnecessary stuff to the API.
>> Johannes, you are just accusing me with blunt statements like that. I 
>> really don't know what to say on your accusations.
> There isn't any accusation or "blunt statement" in my writing.
> I just wanted to give you stuff to think about.
> I asked myself those questions and reached some conclusions
> (which I think were reflected in my postings already). Those
> questions should show you how I reached my conclusions, so
> you can folloow them.

Ok, tell me how do you get a Low Priority stream. Ask yourself this 
question. Since you say that i was wrong, i won't say anything, just 
waiting for your answer.

>> I too agree with not adding unwanted stuff into the API.
> Good.
>>> BTW, I don't claim to be right on my interpretation of the
>>> DVB-S2 spec, however as long as we can't agree (i.e.
>>> no one can give a good explanation why his version
>>> of the DVB-S2 API is the correct one, and *everyone*
>>> can agree on it), I think the while DVB-S2 API is useless.
>> Are there any other versions ?
> There are few different versions of your proposal,
> and my proposal, and Felix' or Mws' original proposal.

I thought updating the patch was the same thing. moeover Mws did clarify 
things on his post.


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