US Robotics fax, new infos and questions

• Messages sorted by:[ date ][ thread ][ subject ][ author ]

On Thu, Apr 08, 1999 at 03:21:41PM +0200, Norbert Preining wrote:
> On Fri, 19 Mar 1999, Gert Döring wrote:
> > Bad :( - back to square one.
> 
> Ok, the situation is like this: The commands sent to the modem are
> more or less the same with efax and sendfax, also the tty-settings.
> The same with the PPM (or so) codes at the end of page/transmission.
> 
> What is left? I thought on the format/way the data is sent to the
> modem/other fax-machine. Is this a possibility?

It's possible.  The modem might be parsing the data to count
lines or detect the end of the page.  efax (unlike sendfax)
decodes the T.4-encoded image data and re-encodes it in real
time.  It makes sure each line contains the right number of
pixels and lines by scaling the original image horizontally and
vertically.  It also adds padding to the ends of the lines to
meet the minimum scan time requirements.  It also generates the
header lines at the top of the page itself (which I believe
sendfax copies in from another file).  So efax might be
"correcting" errors in the T.4 data or may not generate the same
data transmission delays.  I'm just guessing about possible
causes, I don't know how likely these are.

-- 
Ed Casas   edc@cce.com   http://casas.ee.ubc.ca