Re: [libdc1394-devel] Multiple PGR Flea

[Ben A. <baa...@uc...>]

Yes, this did seem to be the problem.
I hadn't considered it previously.
Thanks for the help.
-Ben


  ----- Original Message -----=20
  From: Damien Douxchamps=20
  To: lib...@li...=20
  Sent: Wednesday, September 21, 2005 11:53 PM
  Subject: Re: [libdc1394-devel] Multiple PGR Flea


  Hi Ben, Don,

  On Wed, 2005-09-21 at 12:13 -0700, Don Murray wrote:
  > Hi Ben,
  >=20
  > Are you getting an error message or does the program just hang?
  > Have you tried fewer cameras or slower frame rates?
  >=20
  > Ok, I'm the PGR guy who tries to keep his ear to the ground w.r.t.=20
  > Linux, but the people on this list are more knowledgable on both =
1394 in=20
  > general and libdc1394 in specific.  But... I have a guess.
  >=20
  > >     unsigned int format =3D FORMAT_SVGA_NONCOMPRESSED_1;
  > >     unsigned int mode   =3D MODE_1024x768_MONO;
  > >     unsigned int framerate =3D FRAMERATE_30;
  >=20
  > You should have received the PGR IEEE-1394 Digital Camera Register=20
  > Reference manual with your windows installation (its a pdf in the =
doc=20
  > directory).  On page 68-71 there is a big table that shows the =
various=20
  > formats and frame rates and the pixels or quadlets per packet that =
are=20
  > required.  For 400 Mbps 1394, you are only allowed to allocate 4915=20
  > total bytes per packet for isochronous transfer (something that =
isn't=20
  > specified in our reference... maybe it should be for those of us who =

  > don't have a 1394 DCam spec on our desks).  1024x768 Y 8bit/pixel at =
30=20
  > fps requires 3072 (see the table).  So, even 2 cameras at this=20
  > format/framerate you are going to blow your allowance (i.e. 2*3072 > =

  > 4915).  If you want 4 Fleas on the same bus you are going to need to =

  > slow them down to 7.5 fps which has a bytes per packet of 768 each.
  >=20
  > Anyway, like I said, I'm not an expert in 1394, but I didn't see=20
  > anything in your code to make me think you were using multiple 1394=20
  > buses, so this would be my first guess as to the problem.  Can you =
try=20
  > slowing down to 7.5 fps and see if it works?

  Thanks Don, this is indeed the first thing to check. :-)

  Ben: you say that it does not work but what are the symptoms?

  Damien

  --=20
    _    Damien 'Takahara' Douxchamps, PhD
   ('-   Post-doctoral investigator
   //\   Image Processing Group, NAIST
   V_/_  http://chihara.aist-nara.ac.jp/




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