Re: [gentoo-user] webcam on Gentoo Logitech C270

[meino.cramer@gmx.de]

Joseph <syscon780@gmail.com> [14-12-22 03:52]:
> On 12/21/14 22:08, Alexander Kapshuk wrote:
> >  grep '^CONFIG.*V4L' /usr/src/linux/.config
> >  CONFIG_VIDEO_V4L2=m
> >  CONFIG_V4L_PLATFORM_DRIVERS=y
> >  CONFIG_MEDIA_SUPPORT=m
> >  CONFIG_USB_VIDEO_CLASS=m
> >  CONFIG_USB_VIDEO_CLASS_INPUT_EVDEV=y
> >  CONFIG_USB_GSPCA=m
> >  CONFIG_MEDIA_PCI_SUPPORT=y
> >  grep -s ^LD_PRELOAD .*
> >  .bash_profile:LD_PRELOAD=/usr/lib/libv4l/v4l2convert.so
> >  Also, you may want to try plugging you webcam into a USB2 port, if
> >  available, instead of a USB3 one, as suggested here,
> >  
> >[6]http://linux-kernel.2935.n7.nabble.com/3-15-8-USB-issue-with-uvc-cam
> >  -td920378.html.
> >  Hope this helps.
> 
> When I try to run: guvcview
> 
> I get:
> guvcview 1.6.1
> ALSA lib 
> /var/tmp/portage/media-libs/alsa-lib-1.0.28/work/alsa-lib-1.0.28/src/pcm/pcm.c:2239:(snd_pcm_open_noupdate) 
> Unknown PCM cards.pcm.rear
> ALSA lib 
> /var/tmp/portage/media-libs/alsa-lib-1.0.28/work/alsa-lib-1.0.28/src/pcm/pcm.c:2239:(snd_pcm_open_noupdate) 
> Unknown PCM cards.pcm.center_lfe
> ALSA lib 
> /var/tmp/portage/media-libs/alsa-lib-1.0.28/work/alsa-lib-1.0.28/src/pcm/pcm.c:2239:(snd_pcm_open_noupdate) 
> Unknown PCM cards.pcm.side
> ALSA lib 
> /var/tmp/portage/media-libs/alsa-lib-1.0.28/work/alsa-lib-1.0.28/src/pcm/pcm_route.c:947:(find_matching_chmap) 
> Found no matching channel map
> video device: /dev/video0 ERROR opening V4L2 interface for /dev/video0
> unable to detect video devices on your system (0)
> ERROR opening V4L interface: Permission denied
> Init video returned -1
> VIDIOC_REQBUFS - Failed to delete buffers: Inappropriate ioctl for 
> device (errno 25)
> cleaned allocations - 100%
> Closing portaudio ...OK
> 
> -- 
> Joseph
> 

Hi Joseph,

in conjucntion with the C920 I found that guvcview does not plai well
with it.

First try to get anything from your webcam, before trying Skype or
such - so you have to fight against too many "open ends" or failure
sources.

Do you have gstreamer installed?

Try this command/shell script:
You have to adopt the device options to you setup.
It will record and display the video stream.

#! /bin/zsh
td=`date +%Y-%m-%d-%Hh%Mh%Ss`
fn=c920-$td.mp4  
gst-launch-1.0 v4l2src device=/dev/video1 ! video/x-h264,width=1920,height=1080,framerate=30/1 ! h264parse ! muxout. alsasrc device="hw:3,0" ! queue ! audioconvert ! lamemp3enc ! muxout. matroskamux name=muxout streamable=true ! filesink location=$fn &
mplayer $fn &

HTH!
Best regards,
Meino