Re: [hylafax-users] 2-DMR: faxgetty and faxmodem defaults

[Dmitry Bely <dbely@mail.ru>]

Giulio Orsero <giulioo@pobox.com> writes:

> >> When using faxgetty, 2D is used automatically, if possible.
> >> When using faxmodem (no faxgetty), the default is not to use 2D unless
> >> one says otherwise using appropriate faxmodem parameters.
> >Yes, because without faxgetty Hylafax cannot query the modem's
> >capabilities.
> I understood that there's no way to query capabilities from a class1
> modem, so how does faxgetty decide to do 2D on the modem?
> Maybe, it sees that it's a class1 modem, so that 2D is always possible?

For faxgetty -- yes. For faxmodem -- no.

> And, if so, why can't faxmodem (it can see if it's a class1 by looking
> at config.<devid>) do the same?

Because faxmodem does not parse any config files and does not sent any
commands to the modem.

> > But why is it interesting for you? Normal faxgetty-controlled 
> >operation is always preferable even in send-only environment.
> Because in some cases we use a prog called "callback" that is part of
> mgetty package. callback wants "mgetty" to be in respawn on the line,
> else it won't work. Another reason is that I've not yet been able to
> have adaptive answer to work correctly.

Hmm, it seems to work for other people:

http://www.hylafax.org/HylaFAQ/Q343.php

But software adaptive answer (AdaptiveAnswer parameter etc.) seems to be 
unreliable (if it works at all). Fortunately, my modem supports hardware
adaptive answer (AT+FAA=1) even in Class1 mode :-)

> >Class2/2.0: both the modem and the software should support 2-D
> >Class1:     the software support is enough (Class1 modems have no idea about
> >            data they send/receive) 
> So why doing "faxmodem <devid>" on a class1 modem is not enough to
> enable 2D?

Ask Sam Leffler :-) faxmodem is normally never used, so he probably decided 
to make it "quick and dirty".

> >> 1) why does faxmodem (without any argument) default to tell hfaxd that
> >> the modem has different capabilities than the ones determined by
> >> faxgetty?
> >See above. faxmodem cannot query actual modem's capabilities, so mandatory
> >ones (which are guaranteed to be supported by any modem) are reported by
> But faxmodem knows if the modem operates in class1 or class2.0 by
> looking at config.<devid>, so that in case of a class1 it could enable
> 2D.
> 
> >> 2) if the 1D, 2D, ... does not depend on the modem  for class1, what's
> >> the maximum we can safely use? (0,1)  or  (0,1,2)  or (0,1,2,3) (I'm
> >> referring to http://www.hylafax.org/HylaFAQ/Q803.php)

> >1. Class2 capabilities has nothing to do with Class1.
> Yes, but the only way I could enable 2D with faxmodem on my class1
> modem,  has been to look at that faq of yours and then specify
> capabilities with 
> faxmodem -c'....'

Alas, I was wrong. If you wants 2-D when using faxmodem (not faxgetty), you
really should to specify Class2-style capabilities string even for Class1
modem. Not very obvious, but that's the only way.

> >2. Anything but 1-D MH and 2-D MR is not supported by Hylafax. The same is
> >true for higher resolutions (more than 196x204dpi)
> So the max for the 5th parameter is (0,1)  for a class1 modem?

Yes. 

> Basically, what I'm wondering is "If 2D entirely depends on HylaFAX when
> using a class1 modem, then why doesn't HylaFAX always enable 2D if it
> operates on a class1 modem (either using faxgetty or faxmodem)?"

Hylafax enables 2D automatically when using Class1 modems with faxgetty.

Hope to hear from you soon,
Dmitry




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