Re: flexfax: Large number of errors with Hylafax and ZyXEL Omni modem

[Robert Colquhoun <rjc@trump.net.au>]

Hi Everyone,
I have been looking at the negative retrain problem, it appears perhaps
that it will be quite difficult to solve.

Firstly some temporary workarounds, these will not fix anything but
hopefully will minimise the chance that a receiving machine will reply with
a neg-retrain.  Switch off 2D encoding ie Use2D: No, if the problem still
occurs after that you could try lowering the default resolution down to 98
lines.

Don't do any of the above unless you are currently having problems.

Now the fix.
There are two ways for hylafax to handle this:
1) give up the call and try again later with lowered session parameters
2) lower the session parameters during the call and continue ie on the run

Solution 2 is preferable but will be difficult to implement.  One major
component that is needed are some routines to convert 2D encoded data on
the run back to 1D in a stream type fashion(i am not totally sure this is
possible).  Also some algorithms that reduce resolution accurately(i know
you could simply cut out every second line but would it be readable!  ;-)

ie what is being done is in memory you have a high-res 2D encoded document
which using the above is degraded if need be back to 1D and low-res as it
is transmitted.

It might be easier just to do 1) but hylafax would be much better software
if it could do 2)

If anybody has some better ideas please say!!!!

- Robert