[H-GEN] USB (firewire) on Linux

Paul Gearon pag at PISoftware.com
Tue Apr 16 22:13:41 EDT 2002


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On Sat, 13 Apr 2002, Johann Kwiatkowski wrote:

> as a side note to firewire, I came across a utility (I think this was posted to
> slashdot.com) that allows you to back up to a dvd camera across firewire, from a
> linux box. A standard 90 minute tape was about 10gig from memory. The beauty of
> this (apart from the tinkering value) was that cameras are relatively easy to
> replace, the tapes are easy to get, and the transfer speed is pretty good.

This software also has the "cute" feature of displaying a low-res penguin
on the screen if you try to play the tape back as video.  :-)

The problem with using a miniDV camera in this way is that there is no
read-behind head to check for data integrity.  You can sort of overcome
this by adding a CRC to the stream, and then read the whole tape back
after recording - but that's hardly an professional solution.  However,
it's fine for home use, and you have the added advantage of a camcorder to
play with.

Also to address some of Franks concerns:

> I have not tried firewire but from what I have heard from those who have
> tried it on Windows it has more problems because the implementations are
> even more proprietory. Although I do know someone using it in Windows for
> video transfer and it is working fine.

While there are certainly devices with implementation issues, these a
relatively minor these days.  By definition, IEEE1394 is a standard, and
most devices these days are *reasonably* compliant.  The only real problem
I'm aware of with external ieee1394 drives under Linux is with correct
detection when you hotplug the drive, but it's apparently not a big deal.
MiniDV cameras are fine, but only on kernel 2.4.14.  I've had more recent
kernels lock up on me while reading tapes (fortunately, I don't need
anything from 2.4.18).

> This might interest you too ... from the project page at Sourceforge :-
>
> " If you have 1394 hardware you can now access it under Linux. The supported
> chipsets are Texas Instruments PCILynx/PCILynx2 and OHCI compliant chips
> (produced by various companies). Not supported are the proprietary Sony
> chipset found in various Vaio systems or the Adaptec AIC-5800. Work has been
> done toward support for the Adaptec chip-based cards, but few have
> successfully used it. Please note as well that not all Sony VAIO systems use
> the proprietary chip. Some contain the CXD3222, which is reported to be OHCI
> compliant. "

Fortunately, almost *all* ieee1394 interfaces with the TI chip.  Go down
to Harvey Norman, Tandy or Myers and you'll pick up a card for about $70
that works great under Linux.  They all have TI chips on them.  The same
goes for the majority of notebooks (such as my Dell).

Yes, I've seen the non-standard ports on Sony notebooks, but these things
even have problems under various flavours of Windows (I have a friend with
a Sony miniDV camera and a Sony notebook - and he's spitting chips that he
can't get them to talk to one another under Windows).  They're rare, and
I'd just stay clear of them.

However, I recall that Frank wanted to talk to a USB drive because of the
convenience.  As the owner of a ThumbDrive I know what he means.  External
IEEE1394 drives are not as convenient, and a LOT more expensive, so they
don't solve the same problem.

Like many other people here, I've had a lot of success with USB (M$ mouse,
HP scanner, HP printer, and Logitech webcam).  However, my ThumbDrive
doesn't work since they went and implemented a proprietry protocol (*why*
would they do that?).  I'm in the process of using USBSnoop to figure out
how it works... maybe it's possible to add it into the USB mass storage
drivers in the kernel (so I've *finally* found a good reason to run
Windows!)  I really should have checked for Linux compatibility before
purchase.  <sigh/>

In the meantime, the only mass storage devices mentioned in the kernel are
for compact flash readers, cd writers, and IDE bridges.  Probably not what
you want Frank.  :-(

Regards,
Paul Gearon

Software Engineer                Telephone:   +61 7 3876 2188
Plugged In Software              Fax:         +61 7 3876 4899
http://www.PIsoftware.com        PGP Key available via finger

Catapultam habeo. Nisi pecuniam omnem mihi dabis, ad caput tuum saxum
immane mittam.
(Translation from latin: "I have a catapult. Give me all the money,
or I will fling an enormous rock at your head.")




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