Drivers for regular USB Video Class (UVC) Webcam devices are enabled in our pre-built images. The driver exports the webcam through the Video4Linux2 (V4L2) API. User-space video utilities such as GStreamer can be used to display or store the video stream.
For supported UVC compatible webcams have a look at www.ideasonboard.org/uvc.
[ 102.903321] usb 2-1: new high speed USB device using tegra-ehci and address 2 [ 103.233213] usb 2-1: New USB device found, idVendor=046d, idProduct=0805 [ 103.241038] usb 2-1: New USB device strings: Mfr=0, Product=0, SerialNumber=2 [ 103.248335] usb 2-1: SerialNumber: FC377070 [ 103.253237] uvcvideo: Found UVC 1.00 device(046d:0805) [ 103.297988] input: UVC Camera (046d:0805) as /devices/platform/tegra-ehci.2/usb2/2-1/2-1:1.0/input/input1
Our latest V2.x images for Tegra and i.MX6 based modules come with the required GStreamer Video4Linux2 source pre-installed.
On Vybrid based modules one has to install GStreamer, Video4Linux2 and some additional packages:
# opkg update # opkg install gst-plugins-good-video4linux2 gst-plugins-base-ximagesink gst-plugins-base-ffmpegcolorspace gst-plugins-bad-fbdevsink
For images V2.6 and newer the GStreamer 1.x series needs to be used:
# opkg update # opkg install gstreamer1.0-plugins-base-ximagesink gstreamer1.0-plugins-good-video4linux2 gstreamer1.0-plugins-base-videoconvert gstreamer1.0-plugins-bad-fbdevsink
Pipeline to store the unconverted raw video stream in a file:
gst-launch v4l2src device=/dev/video0 ! video/x-raw-yuv, framerate=10/1, width=320, height=240 ! filesink location=test.raw
Pipline for Tegra based modules using nvxvimagesink (accelerated)
gst-launch v4l2src device=/dev/video0 ! 'video/x-raw-yuv, framerate=30/1, width=640, height=480, format=(fourcc)YUY2' ! nvvidconv ! nvxvimagesink -v
Pipeline for i.MX6 based modules using i.MX6 optimized sink (V2.5: imxv4l2sink, V2.4 and earlier: mfw_v4lsink):
gst-launch v4l2src device=/dev/video0 ! 'video/x-raw-yuv, width=(int)640, height=(int)480, format=(fourcc)YUY2' ! imxv4l2sink disp-width=640 disp-height=480
Pipeline for Vybrid based modules using X-Server window (Software only, tested on Colibri VF61):
gst-launch v4l2src device=/dev/video0 ! 'video/x-raw-yuv,width=320,height=240,framerate=30/1' ! ffmpegcolorspace ! ximagesink
Using GStreamer 1.x series, applicable for Colibri i.MX7 and Colibri i.MX6 ULL after running GStreamer 1.x installation command lines.
# gst-launch-1.0 v4l2src device=/dev/video0 ! 'video/x-raw,width=640,height=480,framerate=30/1' ! videoconvert ! ximagesink
Using an Embedded Linux Image that runs over framebuffer, interchange ximagesink with fbdevsink
# gst-launch-1.0 v4l2src device=/dev/video0 ! 'video/x-raw,width=640,height=480,framerate=30/1' ! videoconvert ! fbdevsink
Pipeline for Vybrid based modules using framebuffer (fbdev) sink (Software only, tested on Colibri VF61):
gst-launch v4l2src device=/dev/video0 ! 'video/x-raw-yuv,width=640,height=480,framerate=15/1' ! ffmpegcolorspace ! fbdevsink
Using GStreamer 1.x series
# gst-launch-1.0 v4l2src device=/dev/video0 ! 'video/x-raw,width=640,height=480,framerate=15/1' ! videoconvert ! fbdevsink
This pipeline is using the CPU to convert color space and composite the video. However, on Colibri VF61, VGA (640x480) with up to 15 frames per second has been tested successfully (~80% CPU load).
Note: The format capabilities of a UVC Webcam can be displayed using v4l2-ctl:
v4l2-ctl --list-formats-ext
If you get the following error when trying to concurrently stream video from multiple USB cameras you may have run out of available USB bandwidth. Try connecting your cameras to independent USB host controllers:
root@colibri-t30:~# gst-launch v4l2src device=/dev/video1 ! 'video/x-raw-yuv, framerate=30/1, width=640, height=480, format=(fourcc)YUY2' ! nvvidconv ! nvxvimagesink -v Setting pipeline to PAUSED ... [ 1762.593772] uvcvideo: Failed to submit URB 0 (-28). ERROR: Pipeline doesn't want to pause. ERROR: from element /GstPipeline:pipeline0/GstV4l2Src:v4l2src0: Error starting streaming on device '/dev/video1'. Additional debug info: /build/linuxdev/oe-core_V2.6.1/build/tmp-glibc/work/armv7at2hf-vfp-neon-angstrom-linux-gnueabi/gst-plugins-good/0.10.31-r8/gst-plugins-good-0.10.31/sys/v4l2/gstv4l2object.c(2230): gst_v4l2_object_start_streaming (): /GstPipeline:pipeline0/GstV4l2Src:v4l2src0: system error: No space left on device Setting pipeline to NULL ... Freeing pipeline ...
