Em Fri, 17 Mar 2017 12:16:08 +0000 Russell King - ARM Linux <li...@armlinux.org.uk> escreveu:
> On Fri, Mar 17, 2017 at 01:02:07PM +0100, Philipp Zabel wrote: > > I think most of the simple, fixed pipeline use cases could be handled by > > libv4l2, by allowing to pass a v4l2 subdevice path to v4l2_open. If that > > function internally would set up the media links to the > > nearest /dev/video interface, propagate format, resolution and frame > > intervals if necessary, and return an fd to the video device, there'd be > > no additional complexity for the users beyond selecting the v4l2_subdev > > instead of the video device. > > ... which would then require gstreamer to be modified too. The gstreamer > v4l2 plugin looks for /dev/video* or /dev/v4l2/video* devices and monitors > these for changes, so gstreamer applications know which capture devices > are available: > > const gchar *paths[] = { "/dev", "/dev/v4l2", NULL }; > const gchar *names[] = { "video", NULL }; > > /* Add some depedency, so the dynamic features get updated upon changes in > * /dev/video* */ > gst_plugin_add_dependency (plugin, > NULL, paths, names, GST_PLUGIN_DEPENDENCY_FLAG_FILE_NAME_IS_PREFIX); > > I haven't checked yet whether sys/v4l2/gstv4l2deviceprovider.c knows > anything about the v4l2 subdevs. Not only gstreamer do that, but all simple V4L2 applications, although on most of them, you can either pass a command line argument or setup the patch via GUI. Btw, I've no idea from where gstreamer took /dev/v4l2 :-) I'm yet to find a distribution using it. On the other hand, /dev/v4l/by-patch and /dev/v4l/by-id are usual directories where V4L2 devices can be found, and should provide persistent names. So, IMHO, gst should prefer those names, when they exist: $ tree /dev/v4l /dev/v4l ├── by-id │ ├── usb-046d_HD_Pro_Webcam_C920_55DA1CCF-video-index0 -> ../../video1 │ └── usb-Sunplus_mMobile_Inc_USB_Web-CAM-video-index0 -> ../../video0 └── by-path ├── platform-3f980000.usb-usb-0:1.2:1.0-video-index0 -> ../../video1 └── platform-3f980000.usb-usb-0:1.5:1.0-video-index0 -> ../../video0 Thanks, Mauro _______________________________________________ devel mailing list de...@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel