Re: flexfax: Incoming faxes trashed

[Dmitry Bely <dbely@mail.ru>]

"James R. Hay" <jrhay@HayA.QC.CA> writes:

> We have hylafax 4.0pl2 compiled on a Red Hat 6.1 system where we also
> compiled tiff version 3.4 (we also tried 3.5).

Don't ever try 3.5 -- it will not work!

> When a fax is received all
> goes well.  When I try to print it the log contains several lines like:
> 
> Bad code word at scanline 265 (x 247)
> 
> When the job goes to the printer I get garbage.  I've tried opening the
> tif file with various different viewers all of which complain about the
> file being corrupted or an error occurring. 

This is pretty normal. Fax protocol (without ECM) is unreliable, and broken 
scan lines sometimes happen. Hylafax by default stores them to TIFF file
"as is".

> Any suggestions of where to look for this?

You have a number of options to change this behaviour:

1. If you use Class2/2.0 modem, and it supports quality checking, try to
enable "receive copy quality correction" in the modem (man config for
Class2CQCmd parameter and your modem's manual). E.g. for Zyxel Elite Class
2.0 the appropriate command would be "AT+FCQ=2,2". Note that many modems
incorrectly reports that they support copy quality checking, although in
fact they do not!

(or)

2. Force Hylafax to check/correct copy quality itself. By default it does
not enabled in Class2/2.0 (if your modem reports CQ capabilities) and can
be achieved with

Class2CQQueryCmd: "!(0),(0)"

in your config.<modem device>
This way Hylafax will reencode the received image, and your viewer will be
quite happy (although visible transmission errors will not disappear).

(or)

3. Write ECM implementation for Hylafax (what I think about from time to
time) :-)))

Hope to hear from you soon,
Dmitry