> On Sun, Apr 25, 2010 at 4:45 PM, Ilm??rs Poik??ns <ilmars at delibero.lv> > wrote: >> Hi, >> >> I'm running latest SANE from git source on Ubuntu 9.10. I was testing >> scaning A4 on Fujitsu ScanSnap 500 in 300 dpi Color uncompressed using >> scanadf. Everything is fine when scanning only one side of sheet (image >> size >> 24MB). But when scanning with "ADF Duplex" as source, scanner pauses 3 >> times >> during scanning. Two 24MB files are saved successfully. Clearly pausing >> is >> caused by data transfer issues somewhere. > > Does this happen on windows? > >> Any ideas where could be the >> bottleneck? Scanner can't send data so fast over USB? > > Almost certainly. > >> Buffer too small for >> USB transfers, so too many data exchange transactions creates delay and >> slowdown of throughput? > > You can try increasing the buffer-size option in /etc/sane.d/fujitsu.conf. >
The config states: # to set data buffer size, in bytes # the value ranges from 4096 - infinity # but you may have scanning problems with # a value larger than 65536 (the default) option buffer-size 65536 I'm just wondering what kind of scanning problem may I have with bigger buffer-size? Does it still apply to version 1.0.21? Simon >> I guess scanner is sending data from duplex scan >> interleaved - data block for front side, data block for back side. > > for the low-memory scanners like the S500, yes. > >> Inefficient processing of such data in fujitsu-backend? Maybe problem >> caused >> by scanadf (or any other frontend), that can read images only one by >> one? >> Any ideas? > > as long as you have enough ram in the system to buffer the back side > image, the backend can usually outrun the scanner. > >> >> What is the status of SANE 2.0? Is there any functionality for >> retrieving >> many images simultaneously from one physical scan, like front and back >> of >> page during duplex scan, several image regions on pages? > > neither of those have been discussed for sane 2.0, but the > 'multi-region' idea is probably a not going to happen. The first idea > actually is already supported by the fujitsu backend. The 'low-memory' > option causes the backend to do alternate transfers if required. You > have to inspect the value of the 'side' option before each transfer to > determine which image the next block will be for. This is only useful > with a custom frontend, as nothing commonly used will support it. > > allan > -- > "The truth is an offense, but not a sin" > > -- > sane-devel mailing list: sane-devel at lists.alioth.debian.org > http://lists.alioth.debian.org/mailman/listinfo/sane-devel > Unsubscribe: Send mail with subject "unsubscribe your_password" > to sane-devel-request at lists.alioth.debian.org
