Re: Reverse-engineering CD printing on the Epson R300

On Tuesday 20 July 2004 12:12, Robert L Krawitz wrote:
>    Understanding it that closely for CD printing may not be too
>    important, however, as it doesn't seem to vary much between very
>    different prints.  Between 0x98 (start of SN instruction) and
>    0x145, all three files are identical.  I doubt the whole 173 bytes
>    are related to the SN instruction, though I daresay anything's
>    possible.
>
> The "SN" is followed by two bytes (little endian short) counting the
> number of bytes following that are part of the command.  So for
> example
>
> SN 3 0
>
> would be followed by 3 more bytes of payload.  Again, the escputil
> command that's part of Gimp-Print is your friend, much more useful
> than hexedit.  SN in particular seems to be somewhat of a catchall
> command.

Great. Do you mean examine the source code of escputil or is there some 
explicit option which I've missed?

> I would expect that all prints to CD's using the same parameters (BW
> vs. color selected, for example) would use the same extended SN
> command.  However, different choices of margin, print speed, and so
> forth would likely cause variations in the command, which may be
> significant.

The alignment of the CD doesn't seem to affect the SN command, neither does 
whether or not it is an 8cm CD or setting it to photo quality.

Either I've misunderstood something or my guess is all the SN command does in 
this context is shunt the printer into "Print CD" mode and everything after 
that is essentially a normal print job.  

I've got a whole bunch of sample print files here, including:

"Normal" - all settings at default, a bit of text or a picture.
Aligned right by 2mm
Aligned left by 2mm
8cm CD
Photo Quality

The SN command's the same in all of them.

-- 
"Ronald McDonald? He's the newsreader, isn't he?"
  - Barbara Evans, demonstrating a typically Welsh grasp of current affairs


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