v4l2_next problem with two webcams

Question

When I have two webcams and I start them seperatly, everything works. When I start them as two threads, both die with the error in verbatim (below). Is it a problem with v4l2 or with USB bandwidth?

Thanks a lot!

[2] v4l2_next: VIDIOC_DQBUF: EIO (s->pframe 0)
[2] v4l2_next: VIDIOC_DQBUF: EIO (s->pframe 1)
[2] v4l2_next: VIDIOC_DQBUF: EIO (s->pframe 0)
[2] v4l2_next: VIDIOC_DQBUF: EIO (s->pframe 1)
[2] v4l2_next: VIDIOC_DQBUF: EIO (s->pframe 0)
[2] v4l2_next: VIDIOC_DQBUF: EIO (s->pframe 1)
[2] v4l2_next: VIDIOC_DQBUF: EIO (s->pframe 0)
[2] v4l2_next: VIDIOC_DQBUF: EIO (s->pframe 1)
[2] v4l2_next: VIDIOC_DQBUF: EIO (s->pframe 0)
[2] v4l2_next: VIDIOC_DQBUF: EIO (s->pframe 1)
[2] Error capturing first image
[2] Thread finishing...

Environment

Motion version:	3.2.8 (daily snapshot)
ffmpeg version:
Libraries:
Server OS:	Linux RHEL AS 5

-- JeanMichelPhilipponNadeau - 01 Aug 2007

Answer

Hi Jean Michel,

Problem seems related to USB bandwidth like in that bug :

http://www.lavrsen.dk/twiki/bin/view/Motion/BugReport2007x07x11x211429

So check that you have a USB 2.0 not a USB 1.1 and try to get a lower resolution when you connect 2 webcams.

-- AngelCarpintero - 01 Aug 2007