[linux-dvb] Re: Documentation for beginners (was AW: Re: Reception of raw TS or multiple PIDS)

[Johannes Stezenbach <js@convergence.de>]

Marcus Metzler wrote:
> Torsten Schlabach writes:
> 
>  > b) Understanding linuxtv.org, linuxdvb.tv, convergence.de, metzlerbros,
>  > a log of CVSs and download links and how they relate to each other e.g.
>  > who's doing what

Convergence develops software for Linux based set top boxes,
including an MHP implementation.
Some of this software is released as open source (like the DVB
and Kfir drivers, or DirectFB). Or we sponsor open source development
for stuff we use in our products, like we do for the dietlibc.

However, there's no reason for Convergence to spend money on the
development of drivers for other companies' PCI cards. The DVB-S
drivers were developed because Siemens wanted them for their
Activy platform, and we continued development because we use
the Activies and Fujitsu-Siemens/Technotrend/Hauppauge cards
as development and demo platforms.

Today our target platforms are embedded/system-on-a-chip type
set top boxes, and noone at Convergence gets payed for any work
on the open source DVB drivers. We try to squeeze that in between
all our other work, but it's difficult.

Anyway, it's open source and anyone can contribute.

> We used to work for convergence, but don't anymore. We don't agree
> with some of the choices they made for driver internals. This doesn't
> concern the API, which should be the same apart from additions we may
> add. We try to stay compatible. If not, tell me.

There are also non-technical issues led to the Metzler's refusal to commit
any more code to the CVS hosted by Convergence. I still hope these
can be worked out some time...

>  > a) Do Convergence and the Metzler brothers develop different drivers for
>  > the same of for different APIs? The API doc that is downloadable from
>  > Linuxtv.org is (c) Convergence and authored by the Metzler brothers but
>  > somewhere else it says that the Metzler brothers are independent driver
>  > developers.

The API was initially developed by Nokia for their OST project,
an open source, Linux based STB. Nokia suggested that we use their
API for our drivers to establish a Linux standard DVB API.
However, the API documentation we got from Nokia was *confidential*,
so Ralph and Marcus wrote a new non-confidential documentation for
Convergence.

>  > b) Up to today I was not able to understand the difference between
>  > oldstruct and newstruct.
> 
> There are some major differences in the tuning API and some minor ones
> in others. The devices have different names (no more cheese aeh ost).
> There are also internal differences which should not matter to the
> application programmer.

The old DVB structure (like it was in siemens_dvb-0.9.4.tar.gz) made
code sharing between differnt DVB drivers difficult, like, in the
CVS you will find a margi module that contains slightly modified
copies of many DVB-S driver files. The goal of NEWSTRUCT was to
restructure the driver sources for better code sharing. We also
got rid of the "ost" in device and include path names.

The other API changes were not really necessary but the one who did
them couldn't hold himself back.

See also http://linuxtv.org/dvb/drivers.xml

>  > c) Most of the tools that are linked to on Linuxtv.org (such as dvbtune,
>  > xcha, etc.) don't compile or don't work (any more). The author of xchan,
> 
> I think most applications have versions for the new API, some may
> require a change in the Makefile and some have still to be rewritten. 

We failed miserably in providing a new release tarball, and people
got tired of chasing the API changes done in CVS.
A release of the current DVB CVS is about to happen rsn.

>  > d) I have posted questions and remarks to the API doc PDF on the
>  > project's site but nobody even cared to answer yet ...
> 
> I don't know if there is some kind of license for the API
> documentation. We wrote it while we were at convergence and used
> material provided by Nokia, so I don't think we or anyone else can just
> take it and change or redistribute it now.
> As I mentioned before, there is also a paper about the talk we gave at
> linux-kongress
> (http://www.linux-kongress.org/2002/papers/lk2002-metzler.html) 
> which gives some introduction to DVB drivers.

Some months ago someone asked on the list and consequently we released
it under the GNU FDL, as you can see in the TeX sources in DVB/doc/ ...
... in NEWSTRUCT. Argh!
I will merge the FDL license into DVB HEAD on monday.

>  > I am an experienced journalist and would be willing to help with the
>  > documentation (I know, most developers don't like doing that, but I do)
>  > but I can only do that if those who have the information at least answer
>  > to questions on the mailing list.
> 
> I can't talk for others, but answering question always depends if I
> have time and the desire to answer the question at the time I read it
> on the mailing list. Sometimes, if I don't answer immediately, I 
> forget or it gets buried somewhere in the mailbox. So, I think it's
> ok to ask more than once.

Same goes for me.


Best regards,
Johannes


-- 
Info:
To unsubscribe send a mail to listar@linuxtv.org with "unsubscribe linux-dvb" as subject.