Re: [PD] pix_video: composite or Firewire ?

2007-11-16 Thread simon wise 

On 16 Nov 2007, at 10:47 AM, Alexandre Quessy wrote:

 I didn't like much using Firewire (ieee1394) under GNU/Linux, since
 the driver is pretty slow.

As I understand it, if you are using DV codec with firewire you are  
going to get several frames delay (on any OS) - I guess this system  
is optimised for capturing media for editing, favouring accuracy  
rather than latency, not so good for real-time use. I have tried many  
different combinations of DV camera and capture system, always there  
are several frames delay with DV. Composite capture cards can be much  
faster, and can be better resolution too - but they get very  
expensive for higher resolutions. Without locking the camera's  
framerate and the capture card together you are always going to get a  
frame or more delay. Very high end digital mixing systems have a  
exactly one frame delay, allowing for processing the signal etc and  
all the cameras are locked in sync.

I settled on a PCI framegrabber from Eurosys, not cheap but quite  
nice, and get a delay of less than 2 frames - just fast enough to get  
away with putting the image of a performer speaking up onstage  
without the sync between live voice and image being too bad.


simon



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Re: [PD] pix_video: composite or Firewire ?

2007-11-15 Thread Olivier Heinry 
Le jeudi 15 novembre 2007 à 18:47 -0500, Alexandre Quessy a écrit :
 Hi all,
 Preparing one more Gem video perf with circus. :) (the 4th!)
 
 I didn't like much using Firewire (ieee1394) under GNU/Linux, since
 the driver is pretty slow.

 What would you guys recommend, if I want to use a nice miniDV camera ?
 It could either be a composite (BNC cable) capture card under
 GNU/Linux or the Firewire uner Mac OS X.

 I've got a conexant BTxxx capture chip on a PCI board. I think the
problem of the analog capture card its the poorer image quality than
Firewire. And delay is quite noticeable to my opinion even on a linux
box.

 
 I think that the BNC cable is more flexible an easier to handle than
 the Firewire. It can also be very long, and that suits my needs, since
 it gives more flexibility to the cameraman.

There is  also the firewire over optic fibre solutions: one of the dance
companies Iw ork with purchased one, and it has an excellent image
quality and very low delay over a 100m fiber. The fiber is actually more
flexible than a cooper coax cable and a lot lighter. The prob with BNC
is the weight of the cable itself which tends to damage  the
camera/peripheral connectors after a while.

See  http://www.kramerelectronics.com/indexes/item.asp?name=648 for one
of the cheapest FW over optic fibre solutions around in France.
++
O.


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Re: [PD] pix_video: composite or Firewire ?

2007-11-15 Thread Jaime Oliver 
I know I have the same problem!! laptops...

anyway

I am trying to get a hand on a point grey to run tests

I found this page that lists uncompressed firewire cameras:
http://damien.douxchamps.net/ieee1394/cameras/index.php

This one seems to have the best pfs for the price (199$), it's called
firefly MV, however I will continue the search:

http://www.ptgrey.com/products/fireflymv/index.asp
http://www.ptgrey.com/products/fireflymv/fireflymv.pdf
http://www.ptgrey.com/products/Point_Grey_imaging_catalog.pdf

good luck and if you get good fps for good price with uncompressed
firewire let me know...

best,

J

On 11/15/07, Olivier Heinry [EMAIL PROTECTED] wrote:
 Le jeudi 15 novembre 2007 à 20:23 -0800, Jaime Oliver a écrit :
  I think your problem may not be in the driver but in the fact that you
  are using DV which compresses both at the camera and in your computer
  bus... (i believe...) I am also looking for the best (and cheapest)
  solution for latency. you should check uncompressed firewire options.

 Coud you name a few?

 
  The conexant 878 chip seems to be the fastest one that i've tried so
  far to capture analog video. it's a 20$ PCI tv tuner

 I'm sorry it's a PCI card now my main machine is a laptop!

 
  On 11/15/07, Olivier Heinry [EMAIL PROTECTED] wrote:
   Le jeudi 15 novembre 2007 à 18:47 -0500, Alexandre Quessy a écrit :
Hi all,
Preparing one more Gem video perf with circus. :) (the 4th!)
   
I didn't like much using Firewire (ieee1394) under GNU/Linux, since
the driver is pretty slow.
  
What would you guys recommend, if I want to use a nice miniDV camera ?
It could either be a composite (BNC cable) capture card under
GNU/Linux or the Firewire uner Mac OS X.
  
I've got a conexant BTxxx capture chip on a PCI board. I think the
   problem of the analog capture card its the poorer image quality than
   Firewire. And delay is quite noticeable to my opinion even on a linux
   box.
  
   
I think that the BNC cable is more flexible an easier to handle than
the Firewire. It can also be very long, and that suits my needs, since
it gives more flexibility to the cameraman.
  
   There is  also the firewire over optic fibre solutions: one of the dance
   companies Iw ork with purchased one, and it has an excellent image
   quality and very low delay over a 100m fiber. The fiber is actually more
   flexible than a cooper coax cable and a lot lighter. The prob with BNC
   is the weight of the cable itself which tends to damage  the
   camera/peripheral connectors after a while.
  
   See  http://www.kramerelectronics.com/indexes/item.asp?name=648 for one
   of the cheapest FW over optic fibre solutions around in France.
   ++
   O.
  
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-- 
Jaime E Oliver LR

[EMAIL PROTECTED]
www.realidadvisual.org/jaimeoliver
www-crca.ucsd.edu/
www.realidadvisual.org

9168 Regents Rd. Apt. G
La Jolla, CA 92037
USA

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