Re: [hylafax-users] 2D and 1D Compression

[Lee Howard <faxguy@deanox.com>]

On 2002.03.09 11:43 lproxy@comcast.net wrote:

> Why does the documentation claim that HylaFAX determines optimal
> compression based on the receiving machine when this is clearly
> not the case?  If the -2 parameter is not specified in the
> sendfax command line, HylaFAX will only produce a 1D compressed
> file from the PostScript input.

HylaFAX determines initial optimal compression by looking at an info file 
which may have been created during a past communication with the remote.  
If there is no info file (it is the first time you've faxed there) then 
the system will always send 1D unless specifically told to otherwise.  
After the first fax is sent to a destination, the actual optimal setting 
will be used.  This is by design - although most of us these days disagree 
with it.

> A good improvement for future versions of HylaFAX should be file
> compression that occurs only *after* a negotiation with the
> receiving fax machine has determined all relevant capabilities.

The design was intentional on the part of Sam Leffler, the original 
HylaFAX author, because there were fears that 1D/2D file 
creation/compression/alteration on-the-fly would jeopardize timing 
sensitivities with the fax protocol.  I think it's safe to say that the 
fears were unwarranted, but remember that this is OLD software, and maybe 
on a 386 it made a big difference.

Don't like it?  Feel free to make an alteration to fix it.  Please post 
your changes, though, for the benefit of others.

Lee.

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