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

[Dmitry Bely <dbely@mail.ru>]

Giulio Orsero <giulioo@pobox.com> writes:

> I use a class1 modem with the latest cvs.
> 
> Reading the faxmodem.8c  man page I understand that while there's a way
> to get class2.0 fax capabilities (at+fcc=?), for class1 all depends on
> the HylaFAX software (except for the signalling rate).

Yes.

> 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. But why is it interesting for you? Normal faxgetty-controlled 
operation is always preferable even in send-only environment.

BTW, Hylafax can only use 2-D while sending a fax to the *known*
destination (according the info database). It cannot dynamically select
coding scheme/resolution etc. basing on the actual remote's capabilities
(as T.30 requires). Now imagine the multi-channel phone number with
*different* fax machines on every line. Arghhh....

> The faxmodem man page says that the default capabilities string is
> (0,1),(0-3),(0-4),(0-2),(0),(0),(0),(0-7)

Default Class2/2.0 capabilies are those that the modem returns in response
to AT+FDCC=?/AT+FCC=? Different modems have different features. You cannot
"enable" 2-D if the modem itself does not support it.

> One needs to specify a capability string with (0,1) as the 5th element
> to enable 2D using faxmodem.

If faxgetty is not used *and* 2-D is supported by modem -- yes. If faxgetty 
is used, the best parameters are enabled by default.

> If the above is true (2D is something HylaFAX has to do for class1, not
> the modem),

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) 

> I have some questions:
> 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
default.

> 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.html)

:-)

1. Class2 capabilities has nothing to do with Class1.
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)
3. Hylafax design makes adding the modern features very problematic :-(

Hope to hear from you soon,
Dmitry




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