[sane-devel] truncated image data when scanning via network

[Jens Gulden]

Hello,

I wrote on 2006-07-20:
> truncated image files on the client, the data just seems to stop at some fixed number of bytes.

The problem even occurs when scanning via localhost-net, i.e. adding "localhost" to 
/etc/sane.d/net.conf and then scan via that. The resulting file is truncated, just like when 
scanning via real network:

# scanimage -d "net:localhost:brother:bus1;dev1" --mode "Black & White" --resolution 300 > 
test-localhost.pbm

-> file-size 1072633 (too short, truncated)

# scanimage -d "brother:bus1;dev1" --mode "Black & White" --resolution 300 > test-dev.pbm

-> file-size 1076353 (ok)

> Both server and client run on Debian packages libsane 1.0.16-4, sane 1.0.14-1 and sane-utils 1.0.16-4.
> brscan-0.2.1-0.i386.deb

Is this a problem of the sane versions, or is something wrong with the Brother driver?

Thanks for help
Jens


Jens Gulden wrote:
> Hello sane people,
> 
> I have started using saned and network-scanning instead of connecting 
> the scanner/printer locally via USB.
> Unfortunately, the maximum size to scan is 210mm x 293mm for black&white 
> scans, which is almost a full-sized A4 image (210mm x 297mm). Attempts 
> to scan larger sizes strangely result in truncated image files on the 
> client, the data just seems to stop at some fixed number of bytes. 
> Scanning on the server (locally via USB) works fine.
> Examples:
> 
> 'scanimage --mode "Black & White" --resolution 300 -x 210 -y 297 > 
> network_bw_300dpi_210x297.pbm'
> network scanning:
> -y 297 : 1072633 bytes (invalid file)
> -y 295 : 1072633 bytes (invalid file)
> -y 294 : 1072633 bytes (invalid file)
> -y 293 : 1072323 bytes (VALID FILE)
> -y 292 : 1068603 bytes (VALID FILE)
> Data seems to be truncated at 1072633 bytes.
> 
> local scanning on the server:
> -y 297 : 1076353 bytes (valid file) ...
> -y 292 : 1068603 bytes (valid file)
> 
> The same occurs when scanning in grayscale, but at a different number of 
> bytes and a slightly different height in mm:
> 
> 'scanimage --mode "True Gray" --resolution 300 -x 210 -y 297 > 
> network_gray_300dpi_210x297.pgm'
> network scanning:
> -y 297 8531237 bytes (invalid file) ...
> -y 292 8531237 bytes (invalid file)
> -y 291 8518837 bytes (VALID FILE)
> Data seems to be truncated at 8531237 bytes.
> 
> Color scanning seems to always result in invalid files for sizes near A4.
> 
> Is this some known behaviour? I haven't found something like this in the 
> list archive.
> 
> The pnm-headers of the truncated files are ok. There are no error 
> messages in the logs or when running saned -d128. Filling up the missing 
> bytes with zeros leads to files which can at least be opened by e.g. 
> gimp (but with the last rows of pixels being just white, of course).
> 
> The scanner/printer is a Brother MFC3420C connected via USB with the 
> SANE driver delivered by Brother (brscan-0.2.1-0.i386.deb). Both server 
> and client run on Debian packages libsane 1.0.16-4, sane 1.0.14-1 and 
> sane-utils 1.0.16-4.
> 
> It would be great if someone has an idea. Thanks,
> Jens
>