Hello,
Do they need to be simultaneous? I.e. from your
description, ideally they would be, but then the higher
the frame-rate the lesser the delta between frames
(assuming your solution moves slowly or observes
something that moves slowly).
Implementation could be interesting. I don't know what
UVC does when you don't de-queue the capture buffer
(VIDIOC_DQBUF), whether the camera captures
frames but doesn't send them to the host over the wire,
or whether the camera captures frames and sends
them to the host to have the host UVC driver dump
them.
*However*
Assuming the former; you could try setting the
frame rate that you want on all of the cameras in
your solution, then running a "capture" thread that
walks the cameras sequentially in a 10-cameras-per-
second walk to DQ them.
If you think you can sustain multiple cameras
simultaneously, then you could kick off (concurrency)
"capture" threads of 10-cameras-per-second for
(total/concurrency) cameras each.
This is silly - I don't remember the timing models -
you should be able to kick off a thread per camera
and use a mutex to prevent unwanted simultanety, and
then use signals with select(?) in each thread to
manage its own timing .. or did that result in a signal
for the process, rather than the thread .. hmm .. maybe
you should be mixing both ideas.
Either way do any further image handling in a
"processing" thread to keep your image handling out
of your capture timing ...
Chalk it up as one thought ;-)
----- Original Message -----
>From: "Dennis Muhlestein" <[email protected]>
>To: <[email protected]>
>Subject: [Linux-uvc-devel] Multiple camera framerate.
>Date: Mon, 26 Apr 2010 14:43:39 -0600
>
> I have a project I've been playing with that uses a number
of cameras to
> construct video from 360 degrees. All cameras can be
configured as long
> as I don't overload the underlying ISO bandwidth limits.
("No space
> left on device." has been discussed a few times on this list.)
>
> The application works well, but I'd like to experiment
with making the
> video quality better. There is always some sheering when
the cameras
> are moving but the higher framerate I can capture at, the
less the
> sheering effect will degrade the video quality.
>
> Can anyone suggest a way to configure the cameras at a
higher framerate
> without overloading the USB bus? Suppose I can read at 10
fps right now
> without overloading the USB bus. I'd like to set the
framerate to 15,
> but still just capture around 10.
>
> Any thoughts?
>
> Thanks
> Dennis
> _______________________________________________
> Linux-uvc-devel mailing list
> [email protected]
> https://lists.berlios.de/mailman/listinfo/linux-uvc-devel
>
--
Ian Latter
Late night coder ..
http://midnightcode.org/
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