It also looks like /dev/video0 is provided specifically for USB webcam support. It is opened, then ioctls use VIDIOC_QBUF to get a frame from the camera. I don't know how this will work with Qt. It looks like I need to build Qt with both android and v4l support? It looks like v4l support in Qt is limited to radio?
> Sent: Tuesday, April 10, 2018 at 11:09 AM > From: "Jason H" <jh...@gmx.com> > To: "interestqt-project.org" <interest@qt-project.org> > Subject: [Interest] USB Webcams in Android? > > I'm wondering what it would take to get USB webcams working in Qt on Android. > It seems that if the kernel already supports it, it will be listed as as > /dev/v* device. > > I'm also wondering what Qt needs to use the device? I plugged it in and it > did not appear in QtMultimedia.availableCameras: > [ > {"deviceId":"back","displayName":"Rear-facing > camera","position":1,"orientation":270}, > {"deviceId":"front","displayName":"Front-facing > camera","position":2,"orientation":90} > ] > > Additionally, it seems that many camera apps don't support USB cameras and > USB camera apps don't support the built-in cameras. > The only hint at what is going on is this line in logcat: 04-10 10:59:05.360 > 14692 14886 I USBMonitor: > name=/dev/bus/usb/001/002,desc=86,busnum=1,devnum=2,rawDesc=[B@6930dda > > > Many thanks! > > Here's what my Android kernel is saying: > [ 2026.007529] PMI: smblib_vbus_regulator_enable: Enabling internal vbus > regulator > [ 2026.014142] msm-dwc3 a800000.ssusb: DWC3 exited from low power mode > [ 2026.019444] xhci-hcd xhci-hcd.0.auto: xHCI Host Controller > [ 2026.019548] xhci-hcd xhci-hcd.0.auto: new USB bus registered, assigned bus > number 1 > [ 2026.026489] xhci-hcd xhci-hcd.0.auto: hcc params 0x0230fe65 hci version > 0x110 quirks 0x00010010 > [ 2026.026595] xhci-hcd xhci-hcd.0.auto: irq 732, io mem 0x0a800000 > [ 2026.027069] usb usb1: New USB device found, idVendor=1d6b, idProduct=0002 > [ 2026.027101] usb usb1: New USB device strings: Mfr=3, Product=2, > SerialNumber=1 > [ 2026.027130] usb usb1: Product: xHCI Host Controller > [ 2026.027156] usb usb1: Manufacturer: Linux 4.4.88-gda039c93611c xhci-hcd > [ 2026.027182] usb usb1: SerialNumber: xhci-hcd.0.auto > [ 2026.035180] hub 1-0:1.0: USB hub found > [ 2026.036400] hub 1-0:1.0: 1 port detected > [ 2026.037148] xhci-hcd xhci-hcd.0.auto: xHCI Host Controller > [ 2026.037195] xhci-hcd xhci-hcd.0.auto: new USB bus registered, assigned bus > number 2 > [ 2026.037435] usb usb2: We don't know the algorithms for LPM for this host, > disabling LPM. > [ 2026.037767] usb usb2: New USB device found, idVendor=1d6b, idProduct=0003 > [ 2026.037798] usb usb2: New USB device strings: Mfr=3, Product=2, > SerialNumber=1 > [ 2026.037825] usb usb2: Product: xHCI Host Controller > [ 2026.037851] usb usb2: Manufacturer: Linux 4.4.88-gda039c93611c xhci-hcd > [ 2026.037877] usb usb2: SerialNumber: xhci-hcd.0.auto > [ 2026.043081] hub 2-0:1.0: USB hub found > [ 2026.043804] hub 2-0:1.0: 1 port detected > [ 2026.342230] usb 1-1: new high-speed USB device number 2 using xhci-hcd > [ 2026.485458] usb 1-1: New USB device found, idVendor=a16f, idProduct=0304 > [ 2026.485503] usb 1-1: New USB device strings: Mfr=2, Product=3, > SerialNumber=0 > [ 2026.485526] usb 1-1: Product: USB2.0 UVC PC Camera > [ 2026.485548] usb 1-1: Manufacturer: GenesysLogic Technology Co., Ltd. > [ 2026.545861] PMI: smblib_set_prop_use_external_vbus_output: VBUS output > source: internal -> extern > > walleye:/dev # ls -al v* > crw-rw---- 1 system camera 81, 128 1970-06-12 03:04 v4l-subdev0 > crw-rw---- 1 system camera 81, 129 1970-06-12 03:04 v4l-subdev1 > crw-rw---- 1 system camera 81, 138 1970-06-12 03:04 v4l-subdev10 > crw-rw---- 1 system camera 81, 139 1970-06-12 03:04 v4l-subdev11 > crw-rw---- 1 system camera 81, 140 1970-06-12 03:04 v4l-subdev12 > crw-rw---- 1 system camera 81, 141 1970-06-12 03:04 v4l-subdev13 > crw-rw---- 1 system camera 81, 142 1970-06-12 03:04 v4l-subdev14 > crw-rw---- 1 system camera 81, 143 1970-06-12 03:04 v4l-subdev15 > crw-rw---- 1 system camera 81, 144 1970-06-12 03:04 v4l-subdev16 > crw-rw---- 1 system camera 81, 145 1970-06-12 03:04 v4l-subdev17 > crw-rw---- 1 system camera 81, 146 1970-06-12 03:04 v4l-subdev18 > crw-rw---- 1 system camera 81, 147 2018-04-10 09:47 v4l-subdev19 > crw-rw---- 1 system camera 81, 130 1970-06-12 03:04 v4l-subdev2 > crw-rw---- 1 system camera 81, 148 2018-04-10 09:47 v4l-subdev20 > crw-rw---- 1 system camera 81, 131 1970-06-12 03:04 v4l-subdev3 > crw-rw---- 1 system camera 81, 132 1970-06-12 03:04 v4l-subdev4 > crw-rw---- 1 system camera 81, 133 1970-06-12 03:04 v4l-subdev5 > crw-rw---- 1 system camera 81, 134 1970-06-12 03:04 v4l-subdev6 > crw-rw---- 1 system camera 81, 135 1970-06-12 03:04 v4l-subdev7 > crw-rw---- 1 system camera 81, 136 1970-06-12 03:04 v4l-subdev8 > crw-rw---- 1 system camera 81, 137 1970-06-12 03:04 v4l-subdev9 > crw------- 1 root root 10, 95 1970-06-12 03:04 vga_arbiter > crw-rw---- 1 system camera 81, 0 1970-06-12 03:04 video0 > crw-rw---- 1 system camera 81, 1 1970-06-12 03:04 video1 > crw-rw---- 1 system camera 81, 2 1970-06-12 03:04 video2 > crw-rw---- 1 system camera 81, 3 1970-06-12 03:04 video3 > crw-rw---- 1 system camera 81, 32 1970-06-12 03:04 video32 > crw-rw---- 1 system camera 81, 33 1970-06-12 03:04 video33 > crw-rw---- 1 system camera 81, 4 2018-04-10 09:47 video4 > crw-rw---- 1 system camera 81, 5 2018-04-10 09:47 video5 > crw-rw-rw- 1 root root 10, 47 1970-06-12 03:04 vndbinder > _______________________________________________ > Interest mailing list > Interest@qt-project.org > http://lists.qt-project.org/mailman/listinfo/interest > _______________________________________________ Interest mailing list Interest@qt-project.org http://lists.qt-project.org/mailman/listinfo/interest