[pvrusb2] PVR-USB2 and DVB-T

[Michael Krufky]

leonardo wrote:
> 
> thanks a lot for your answer, but if there is no DVB
> support, what exactly are the DVB references in the
> driver webpage referring to?
> 
> from main page:
> "No DVB support. Your author here needs to learn about
> Linux DVB architecture first, but my gut feeling is
> that this should be doable."
> 
> and:
> http://www.isely.net/pvrusb2/usage.html#DVB

Mike Isely is the author in question, here.  The most meaningful piece
of information in the DVB section of the pvrusb2 web page is the part
that reads, "Your author here needs to learn about Linux DVB
architecture first"  (no offense, Mike) :-P

Anyhow, some clarification...

What Mike meant by, "I have several interesting thoughts towards also
making a DVB interface concurrently available"  , what he had in mind
was to make the mpeg2 stream accessible via the DVB kernel API -- he did
NOT intend on implementing DVB support for a piece of hardware that
lacks DVB tuner capability.

I agree that the paragraph on the web site is misleading.  It might be a
good idea to restructure the mpeg encoding API such that it would be
able to use the DVB interface, but this also has many implications that
we are not yet ready to deal with.  The largest implication is the fact
that the analog API, (including analog MPEG encoding) is completely
separate from the DVB API.   The truth of the matter is, this is a folly
that happened long ago when these kernel subsystems were originally
created.  To go back and change things now is a big task, and it will be
quite difficult to get the other developers to agree with it.  That
doesnt stop us from doing it, however... We just cannot expect to see
such changes like that merged into the mainline kernel -- at least not
quickly.

Mike says on his web site that, "The internal architecture of the driver
should make this sort of stunt possible,"  but if something like that
should happen, IMHO, it should be done somewhere in a central core part
of v4l, so that the other mpeg encoders could do the same.  However, I
fear that Mike may disagree with me about this, largely because the
pvrusb2 driver is already structured in such a way that adding
interfaces like this would be quite easy to do, without having to mess
in core v4l stuff.  I'm sure that Mike will have a lot to say on this
topic when he gets back.

Of course, Mike and I have been throwing some ideas around, such that
pvrusb2 itself may end up being the core of a larger driver, in which
case this idea will gradually become more feasable.

On the bright side, I mentioned to you earlier a company called, "Sasem"
..  They have given Mike and I some samples of their hybrid analog mpeg
encoder / ATSC receiver device.  This particular device ALREADY works in
analog mpeg encoder mode with the pvrusb2 driver (except the pvrusb2
driver needs some massaging in order to get it to play nice with the
Cirrus Logic CS53L32A audio ADC) , and I also do have a (50% working)
driver written to handle the ATSC (HDTV in USA) side.  The biggest
problem right now is that we have two separate drivers to handle the
separate functionality. Mike and I have plans to work this out
(hopefully) within the next few months.  Unfortunately, we are both very
busy with our full-time jobs.....  but we will get there sooner or later.

This email turned into a long ramble... I hope that I answered your
question sufficiently, along with providing a lot more info that you may
(or may not) actually be interested in.

If you have any more questions, I'd be happy to try to answer them.

Cheers,

Michael Krufky