[linux-dvb] Multiple frontends on a single adapter support

[linux-dvb] Multiple frontends on a single adapter support

[Christophe Thommeret]

Hi all,

( Please don't mix this thread with the "DVB-S2 / Multiproto and future 
modulation support" thread. )

Summary:

Some devices provide several tuners, even of different types.
So called "Dual" or "Twin" tuners can be used at the same time.
Some others (like HVR4000) can't be used at the same time.

My initial question was: How could an application know that 2 (or more) tuners 
are exclusive (when one is used the other(s) is(are) not free.)

I suggested the following:
Since actually all multiple tuners drivers expose several fontend0 in separate 
adapters, maybe a solution for exclusive tuners could be to have :
- adapter0/frontend0 -> S/S2 tuner
- adapter0/frontend1 -> T tuner
so, an application could assume that these tuners are exclusive.

Janne Grunau acked the idea and said that an experimental driver for HVR4000 
is already doing this.

This was confirmed by Steven Toth:
"Correct, frontend1, demux1, dvr1 etc. All on the same adapter. The 
driver and multi-frontend patches manage exclusive access to the single 
internal resource."
	
Andreas Oberritter said:
"This way is used on dual and quad tuner Dreambox models." (non exclusive 
tuners).
"How about dropping demux1 and dvr1 for this adapter (exclusive tuners), since 
they don't create any benefit? IMHO the number of demux devices should always 
equal the number of simultaneously usable transport stream inputs."

Uri Shkolnik said:
"Some of the hardware devices which using our chipset have two tuners per 
instance, and should expose 1-2 tuners with 0-2 demux (TS), since not all DTV 
standard are TS based, and when they are (TS based), it depends when you are 
using two given tuners together (diversity  mode, same content) or each one 
is used separately (different frequency and modulation, different content, 
etc.)."



So, here are my questions:

@Steven Toth:
What do you think of Andreas' suggestion? Do you think it could be done that 
way for HVR4000 (and 3000?) ?

@Uri Shkolnik:
Do you mean that non-TS based standards don't make use of multiplexing at all?


-- 
Christophe Thommeret


_______________________________________________
linux-dvb mailing list
linux-dvb@linuxtv.org
http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb

[linux-dvb] Multiple frontends on a single adapter support

[Christophe Thommeret]

Hi all,

( Please don't mix this thread with the "DVB-S2 / Multiproto and future 
modulation support" thread (like i did:) )

Summary:

Some devices provide several tuners, even of different types.
So called "Dual" or "Twin" tuners can be used at the same time.
Some others (like HVR4000) can't be used at the same time.

My initial question was: How could an application know that 2 (or more) tuners 
are exclusive (when one is used the other(s) is(are) not free.)

I suggested the following:
Since actually all multiple tuners drivers expose several fontend0 in separate 
adapters, maybe a solution for exclusive tuners could be to have :
- adapter0/frontend0 -> S/S2 tuner
- adapter0/frontend1 -> T tuner
so, an application could assume that these tuners are exclusive.

Janne Grunau acked the idea and said that an experimental driver for HVR4000 
is already doing this.

This was confirmed by Steven Toth:
"Correct, frontend1, demux1, dvr1 etc. All on the same adapter. The 
driver and multi-frontend patches manage exclusive access to the single 
internal resource."
        
Andreas Oberritter said:
"This way is used on dual and quad tuner Dreambox models." (non exclusive 
tuners).
"How about dropping demux1 and dvr1 for this adapter (exclusive tuners), since 
they don't create any benefit? IMHO the number of demux devices should always 
equal the number of simultaneously usable transport stream inputs."

Uri Shkolnik said:
"Some of the hardware devices which using our chipset have two tuners per 
instance, and should expose 1-2 tuners with 0-2 demux (TS), since not all DTV 
standard are TS based, and when they are (TS based), it depends when you are 
using two given tuners together (diversity  mode, same content) or each one 
is used separately (different frequency and modulation, different content, 
etc.)."



So, here are my questions:

@Steven Toth:
What do you think of Andreas' suggestion? Do you think it could be done that 
way for HVR4000 (and 3000?) ?

@Uri Shkolnik:
Do you mean that non-TS based standards don't make use of multiplexing at all?

-- 
Christophe Thommeret


_______________________________________________
linux-dvb mailing list
linux-dvb@linuxtv.org
http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb

Re: [linux-dvb] Multiple frontends on a single adapter support

[Uri Shkolnik]

--- On Thu, 9/11/08, Christophe Thommeret <hftom@free.fr> wrote:

> From: Christophe Thommeret <hftom@free.fr>
> Subject: [linux-dvb] Multiple frontends on a single adapter support
> To: linux-dvb@linuxtv.org
> Date: Thursday, September 11, 2008, 4:35 PM
> Hi all,
> 
> ( Please don't mix this thread with the "DVB-S2 /
> Multiproto and future 
> modulation support" thread. )
> 
> Summary:
> 
> Some devices provide several tuners, even of different
> types.
> So called "Dual" or "Twin" tuners can
> be used at the same time.
> Some others (like HVR4000) can't be used at the same
> time.
> 
> My initial question was: How could an application know that
> 2 (or more) tuners 
> are exclusive (when one is used the other(s) is(are) not
> free.)
> 
> I suggested the following:
> Since actually all multiple tuners drivers expose several
> fontend0 in separate 
> adapters, maybe a solution for exclusive tuners could be to
> have :
> - adapter0/frontend0 -> S/S2 tuner
> - adapter0/frontend1 -> T tuner
> so, an application could assume that these tuners are
> exclusive.
> 
> Janne Grunau acked the idea and said that an experimental
> driver for HVR4000 
> is already doing this.
> 
> This was confirmed by Steven Toth:
> "Correct, frontend1, demux1, dvr1 etc. All on the same
> adapter. The 
> driver and multi-frontend patches manage exclusive access
> to the single 
> internal resource."
> 	
> Andreas Oberritter said:
> "This way is used on dual and quad tuner Dreambox
> models." (non exclusive 
> tuners).
> "How about dropping demux1 and dvr1 for this adapter
> (exclusive tuners), since 
> they don't create any benefit? IMHO the number of demux
> devices should always 
> equal the number of simultaneously usable transport stream
> inputs."
> 
> Uri Shkolnik said:
> "Some of the hardware devices which using our chipset
> have two tuners per 
> instance, and should expose 1-2 tuners with 0-2 demux (TS),
> since not all DTV 
> standard are TS based, and when they are (TS based), it
> depends when you are 
> using two given tuners together (diversity  mode, same
> content) or each one 
> is used separately (different frequency and modulation,
> different content, 
> etc.)."
> 
> 
> 
> So, here are my questions:
> 
> @Steven Toth:
> What do you think of Andreas' suggestion? Do you think
> it could be done that 
> way for HVR4000 (and 3000?) ?
> 
> @Uri Shkolnik:
> Do you mean that non-TS based standards don't make use
> of multiplexing at all?
> 

Take CMMB for example, some standard's options are that the content is RTP based, so the content path is via the IP stack, another CMMB mode is Mpeg4 frames. 
DAB (and DAB-IP) are other good examples.

By demux.h ( http://www.linuxtv.org/cgi-bin/viewcvs.cgi/dvb-kernel-v4/linux/include/linux/dvb/demux.h?view=markup ) demux is "de-multiplexing of a transport stream (TS)", since those standards are not TS based, they can not be "demuxed". If its an IP-based DTV standard, you just create a pipe from the device into the IP stack and pass all content. If it a frames based standards, you need other mechanism, anyway, you don't need a demux 

> 
> -- 
> Christophe Thommeret
> 
> 
> _______________________________________________
> linux-dvb mailing list
> linux-dvb@linuxtv.org
> http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb


      

_______________________________________________
linux-dvb mailing list
linux-dvb@linuxtv.org
http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb

Re: [linux-dvb] Multiple frontends on a single adapter support

[Andreas Oberritter]

Christophe Thommeret wrote:
> Uri Shkolnik said:
> "Some of the hardware devices which using our chipset have two tuners per 
> instance, and should expose 1-2 tuners with 0-2 demux (TS), since not all DTV 
> standard are TS based, and when they are (TS based), it depends when you are 
> using two given tuners together (diversity  mode, same content) or each one 
> is used separately (different frequency and modulation, different content, 
> etc.)."
> 
> 
> 
> So, here are my questions:
> 
> @Steven Toth:
> What do you think of Andreas' suggestion? Do you think it could be done that 
> way for HVR4000 (and 3000?) ?
> 
> @Uri Shkolnik:
> Do you mean that non-TS based standards don't make use of multiplexing at all?
> 

I guess diversity mode should be transparent to the user, so such a
device would register only one frontend (and thus only one demux) per
set of tuners used in diversity mode.

While your statements about non-TS based standards make sense, those
standards would require further work to be covered by a future API. In
this special case, however, we're discussing correct usage of the
current (TS based) demux API.

Regards,
Andreas

_______________________________________________
linux-dvb mailing list
linux-dvb@linuxtv.org
http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb

Re: [linux-dvb] Multiple frontends on a single adapter support

[Uri Shkolnik]

--- On Thu, 9/11/08, Andreas Oberritter <obi@linuxtv.org> wrote:

> From: Andreas Oberritter <obi@linuxtv.org>
> Subject: Re: [linux-dvb] Multiple frontends on a single adapter support
> To: 
> Cc: linux-dvb@linuxtv.org
> Date: Thursday, September 11, 2008, 6:16 PM
> Christophe Thommeret wrote:
> > Uri Shkolnik said:
> > "Some of the hardware devices which using our
> chipset have two tuners per 
> > instance, and should expose 1-2 tuners with 0-2 demux
> (TS), since not all DTV 
> > standard are TS based, and when they are (TS based),
> it depends when you are 
> > using two given tuners together (diversity  mode, same
> content) or each one 
> > is used separately (different frequency and
> modulation, different content, 
> > etc.)."
> > 
> > 
> > 
> > So, here are my questions:
> > 
> > @Steven Toth:
> > What do you think of Andreas' suggestion? Do you
> think it could be done that 
> > way for HVR4000 (and 3000?) ?
> > 
> > @Uri Shkolnik:
> > Do you mean that non-TS based standards don't make
> use of multiplexing at all?
> > 
> 
> I guess diversity mode should be transparent to the user,
> so such a
> device would register only one frontend (and thus only one
> demux) per
> set of tuners used in diversity mode.
> 
> While your statements about non-TS based standards make
> sense, those
> standards would require further work to be covered by a
> future API. In
> this special case, however, we're discussing correct
> usage of the
> current (TS based) demux API.
> 
> Regards,
> Andreas
> 


Regarding the diversity mode - Need to be kept flexible, a device can switch mode (between using a given set of tuners as input for single content or use each tuner for different content)

Regarding Non-TS - I must disagree, there are several posts on this ML that contradict your assumptions, and (much) more important, CMMB after two months of service has much bigger deployment than DVB-H, DVB-T2 and DVB-S2 putting together. T-DMB (DAB) also has much bigger audience.

The optimum is to support all DTV standards :-) , but facing the reality, we must set some priority, and I think the priority should be base on the current users number, and the forecast of DTV standards "market share".

Uri


      

_______________________________________________
linux-dvb mailing list
linux-dvb@linuxtv.org
http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb

Re: [linux-dvb] Multiple frontends on a single adapter support

[Steven Toth]

> Andreas Oberritter said:
> "This way is used on dual and quad tuner Dreambox models." (non exclusive 
> tuners).
> "How about dropping demux1 and dvr1 for this adapter (exclusive tuners), since 
> they don't create any benefit? IMHO the number of demux devices should always 
> equal the number of simultaneously usable transport stream inputs."

...

> 
> So, here are my questions:
> 
> @Steven Toth:
> What do you think of Andreas' suggestion? Do you think it could be done that 
> way for HVR4000 (and 3000?) ?

Could it, yes. I'll go with the majority on this to be honest.

As far as I'm concerned the hvr3000 patches (if you read the patch 
description) were not to be merged as-is, they were for discussion and 
review. It's encouraging good to see that discussion happening now, 
later than expect, but good.

The inodes largely reflect API usage so it needs to be obvious, if we 
think this isn't, then we should come to a consensus and resolve for the 
future.

Obviously, the impact would be that existing applications that are using 
unofficial patches would have to be patched again, away from the current 
approach.

- Steve



_______________________________________________
linux-dvb mailing list
linux-dvb@linuxtv.org
http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb

Re: [linux-dvb] Multiple frontends on a single adapter support

[Andreas Oberritter]

Uri Shkolnik wrote:
>> From: Andreas Oberritter <obi@linuxtv.org>
>> While your statements about non-TS based standards make
>> sense, those
>> standards would require further work to be covered by a
>> future API. In
>> this special case, however, we're discussing correct
>> usage of the
>> current (TS based) demux API.
> 
> Regarding the diversity mode - Need to be kept flexible, a device can switch mode (between using a given set of tuners as input for single content or use each tuner for different content)
> 
> Regarding Non-TS - I must disagree, there are several posts on this ML that contradict your assumptions, and (much) more important, CMMB after two months of service has much bigger deployment than DVB-H, DVB-T2 and DVB-S2 putting together. T-DMB (DAB) also has much bigger audience.

Maybe my phrasing was unclear. "Future API" shall mean any API not
covered by  Linux 2.6 _now_. I.e. "future API" is any of S2API or
multiproto or whatever extension will eventually be merged into the
upstream kernel in the future.

What we are discussing here is an implementation detail for a driver
using the _current_ API (unless someone thinks that the API needs to be
changed to support the two tuners of the HVR4000).

Please keep your suggestions for yet unimplemented transmission methods
in a seperate thread.

Regards,
Andreas


_______________________________________________
linux-dvb mailing list
linux-dvb@linuxtv.org
http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb