[Novalug] [Hardware] How do you connect a video source to a typical desktop box
Bryan J. Smith
b.j.smith at ieee.org
Thu Oct 1 12:17:37 EDT 2009
FireWire was designed from day 1 to not merely be a block interface,
but an intelligent, full command set for not just host to target or target
to target, but even targets commanding hosts. This was illustrated best
when the first FireWire drives hit and people were walking into super-
stores, plugging into Macs and downloading full software sets without
even logging into the system. If you have a FireWire device with such
support for video control, then Kino should work flawlessly with it.
Hardware encoders today are so inexpensive, they are typically added
peripherals on an ARM core with a small buffer in an external device,
allowing direct MPEG-2 encoding, plus the less intensive MJPEG
or DV if you want to do frame editing. The resulting stream over the
external cable is then sub-1MBps for 480p MPEG-2, or up to 6MBps
for MJPEG (and a constant 3.6MBps with DV IIRC?). Unfortunately most
of them are software driven, even if the on-board encoder is intelligent,
and not independently autonomous, so they don't feature FireWire as an
option, let alone must have a Windows software driver.
More expensive will be DVD/VHS combos that have full FireWire
connection and commanding. They've come down in recent years,
and I found an open box one at Best Buy for a steal (although the VHS
side has been screwing up, and I could command the VHS side). I
wouldn't know what to point you to in that regard, as the options and
features will vary. This is the one advantage over using an internal
capture card, being that FireWire could drive the device -- most definitely
the DVD side, if not the VHS side as well.
In all honesty, it might be worth finding a FireWire video camera that can
take a NTSC feed in over AV/S-Video, and leverage its encoder for 480p
output back to the FireWire. Kino could drive the camera capture, although
the device you're inputting via AV/S-Video would not be. But typically
one streams in the entire tape anyway as MJPEG, and then edits. I had
a Matrox Marvel G200 with MJPEG codec built-in back in 1997, but by
2002, I had a Digital 8 video camera that could take an AV/S-Video in
and encode everything into DV feed back through the FireWire.
 MPEG-2 is inter-frame compression of compressed frames. MJPEG
(motion JPEG) and DV are only compressed frames, but not compression
between frames. The latter two are recommended if you're going to edit.
MJPEG uses a fixed compression ratio (at least for the segment being
encoded), so the output rate varies between 1-6MBps typical. DV uses
a fixed size, and varies the compression ratio to fix it (3.6MBps at 480p
and 2.4MBps at 384p was it?). In the late '90s, MJPEG codecs got cheap
enough to be inexpensive ($20 for the IC, $100-200 for device) but in
the last 5 years, full MPEG-2+ codecs are now just as cheap. They are
even fabbed as a peripheral ASIC on a core into a single IC for a few
bucks. So the key will be to find something that does a full FireWire
command set in an external device. Kino can do the rest.
----- Original Message ----
From: Bonnie Dalzell <bdalzell at qis.net>
I need to connect video sources - my analog vhs tape player and a dvd
player to my desktop Ubuntu linux tower. The tower has USB 2 and Firewire
ports as well as ethernet.
Am I best off buying some sort of external video to firewire device. Do
these deliver a standard signal that programs like Kino can interact with
or do they have different signals and I need to get one where the
software for linux exits?
Alternatively will a tv tuner card inside the computer be the best choice?
I have looked at some articles at Ubuntu lists and at other articles I
have googled but their posting dates are often 4 or 5 years ago.
Does anyone know if the input device can make a difference in the quality
of the images? Especially when pulling them off vhs tapes? My vhs
camera that I used for the tapes was a professional grade
camera in its day but that was 15 years ago.
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