webcam forwarding broken in fedora 28

[totaam]

Issue migrated from trac ticket # 1833

component: server | priority: major | resolution: fixed

2018-05-08 14:51:38: antoine created the issue

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Could be an update to the kernel, or the v4l2loopback driver

See also Webcam.

The error:

$ XPRA_ALL_DEBUG=1 python2 ./unittests/unit/server/source_mixins_test.py 
2018-05-08 20:51:02,990 av-sync support is disabled, setting it to 0
2018-05-08 20:51:02,990 av-sync: server=False, client=True, total=0
2018-05-08 20:51:02,990 av-sync support is disabled, setting it to 0
2018-05-08 20:51:02,990 av-sync: server=False, client=False, total=0
2018-05-08 20:51:02,990 av-sync set to 170ms (from client queue latency=150, encoder latency=20, delta=0)
2018-05-08 20:51:02,990 av-sync: server=True, client=True, total=170
2018-05-08 20:51:02,990 av-sync set to 20ms (from client queue latency=0, encoder latency=20, delta=0)
2018-05-08 20:51:02,990 av-sync: server=True, client=False, total=20
.2018-05-08 20:51:02,991 client screen sizes: []
.2018-05-08 20:51:02,991 client uuid None
.2018-05-08 20:51:03,026 get_virtual_video_devices(True) CHECK_VIRTUAL_CAPTURE=True
2018-05-08 20:51:03,028 v4l2.pusher init
2018-05-08 20:51:03,029 * COLORSPACE_STR
2018-05-08 20:51:03,029   - 1                             : SMPTE170M
2018-05-08 20:51:03,029   - 2                             : SMPTE240M
2018-05-08 20:51:03,029   - 3                             : REC709
2018-05-08 20:51:03,029   - 5                             : 470_SYSTEM_M
2018-05-08 20:51:03,029   - 6                             : 470_SYSTEM_BG
2018-05-08 20:51:03,029   - 8                             : SRGB
2018-05-08 20:51:03,029 * FIELD_STR
2018-05-08 20:51:03,029   - 1                             : None
2018-05-08 20:51:03,029   - 2                             : Top
2018-05-08 20:51:03,029   - 3                             : Bottom
2018-05-08 20:51:03,029   - 4                             : Interlaced
2018-05-08 20:51:03,029   - 5                             : SEQ TB
2018-05-08 20:51:03,029   - 6                             : SEQ BT
2018-05-08 20:51:03,029   - 7                             : ALTERNATE
2018-05-08 20:51:03,029 * FORMAT_STR
2018-05-08 20:51:03,029   - 0x3132564e                    : NV21
2018-05-08 20:51:03,029   - 0x3231564e                    : NV12
2018-05-08 20:51:03,029   - 0x3447504d                    : MPEG4
2018-05-08 20:51:03,029   - 0x32315559                    : YUV420P
2018-05-08 20:51:03,030   - 0x32315659                    : YVU420P
2018-05-08 20:51:03,030   - 0x33424752                    : RGB
2018-05-08 20:51:03,030   - 0x33524742                    : BGR
2018-05-08 20:51:03,030   - 0x34363248                    : H264
2018-05-08 20:51:03,030   - 0x34424752                    : RGBX
2018-05-08 20:51:03,030   - 0x34524742                    : BGRX
2018-05-08 20:51:03,030   - 0x39565559                    : YUV410P
2018-05-08 20:51:03,030   - 0x50313134                    : YUV411P
2018-05-08 20:51:03,030   - 0x50323234                    : YUV422P
2018-05-08 20:51:03,030   - 0x56595559                    : YUYV
2018-05-08 20:51:03,030   - 0x59455247                    : GREY
2018-05-08 20:51:03,030   - 0x59565955                    : UYVY
2018-05-08 20:51:03,030 v4l2 using device /dev/video2
2018-05-08 20:51:03,030 ioctl(/dev/video2, VIDIOC_QUERYCAP, 0x7ffd158582a0)=0
2018-05-08 20:51:03,030 devices: {2: {'card': 'Dummy video device (0x0000)', 'version': 266245, 'device_caps': ['VIDEO_CAPTURE', 'VIDEO_OUTPUT', 'DEVICE_CAPS', 'READWRITE', 'VIDEO_M2M_MPLANE', 'STREAMING', 'EXT_PIX_FORMAT'], 'device': '/dev/video2', 'driver': 'v4l2 loopback', 'capabilities': ['VIDEO_CAPTURE', 'VIDEO_OUTPUT', 'DEVICE_CAPS', 'READWRITE', 'VIDEO_M2M_MPLANE', 'STREAMING', 'EXT_PIX_FORMAT'], 'bus_info': 'platform:v4l2loopback-000'}}
2018-05-08 20:51:03,030 found 1 virtual video device
2018-05-08 20:51:03,030 start_virtual_webcam(0, 640, 480)
2018-05-08 20:51:03,030 get_virtual_video_devices(True) CHECK_VIRTUAL_CAPTURE=True
2018-05-08 20:51:03,030 v4l2 using device /dev/video2
2018-05-08 20:51:03,030 ioctl(/dev/video2, VIDIOC_QUERYCAP, 0x7ffd15857fd0)=0
2018-05-08 20:51:03,031 devices: {2: {'card': 'Dummy video device (0x0000)', 'version': 266245, 'device_caps': ['VIDEO_CAPTURE', 'VIDEO_OUTPUT', 'DEVICE_CAPS', 'READWRITE', 'VIDEO_M2M_MPLANE', 'STREAMING', 'EXT_PIX_FORMAT'], 'device': '/dev/video2', 'driver': 'v4l2 loopback', 'capabilities': ['VIDEO_CAPTURE', 'VIDEO_OUTPUT', 'DEVICE_CAPS', 'READWRITE', 'VIDEO_M2M_MPLANE', 'STREAMING', 'EXT_PIX_FORMAT'], 'bus_info': 'platform:v4l2loopback-000'}}
2018-05-08 20:51:03,031 found 1 virtual video device
2018-05-08 20:51:03,031 trying device 2: {'card': 'Dummy video device (0x0000)', 'version': 266245, 'device_caps': ['VIDEO_CAPTURE', 'VIDEO_OUTPUT', 'DEVICE_CAPS', 'READWRITE', 'VIDEO_M2M_MPLANE', 'STREAMING', 'EXT_PIX_FORMAT'], 'device': '/dev/video2', 'driver': 'v4l2 loopback', 'capabilities': ['VIDEO_CAPTURE', 'VIDEO_OUTPUT', 'DEVICE_CAPS', 'READWRITE', 'VIDEO_M2M_MPLANE', 'STREAMING', 'EXT_PIX_FORMAT'], 'bus_info': 'platform:v4l2loopback-000'}
2018-05-08 20:51:03,031 v4l2 using device /dev/video2
2018-05-08 20:51:03,031 ioctl(/dev/video2, VIDIOC_QUERYCAP, 0x7ffd15858280)=0
2018-05-08 20:51:03,031 ioctl(/dev/video2, VIDIOC_G_FMT, 0x7ffd158582f0)=-1
2018-05-08 20:51:03,031 ioctl(/dev/video2, VIDIOC_S_FMT, 0x7ffd158582f0)=-1
2018-05-08 20:51:03,031 start_virtual_webcam(0, 640, 480) error on device 2: {'card': 'Dummy video device (0x0000)', 'version': 266245, 'device_caps': ['VIDEO_CAPTURE', 'VIDEO_OUTPUT', 'DEVICE_CAPS', 'READWRITE', 'VIDEO_M2M_MPLANE', 'STREAMING', 'EXT_PIX_FORMAT'], 'device': '/dev/video2', 'driver': 'v4l2 loopback', 'capabilities': ['VIDEO_CAPTURE', 'VIDEO_OUTPUT', 'DEVICE_CAPS', 'READWRITE', 'VIDEO_M2M_MPLANE', 'STREAMING', 'EXT_PIX_FORMAT'], 'bus_info': 'platform:v4l2loopback-000'}
Traceback (most recent call last):
  File "/usr/lib64/python2.7/site-packages/xpra/server/source/webcam_mixin.py", line 100, in start_virtual_webcam
    p.init_context(w, h, w, src_format, device_str)
  File "xpra/codecs/v4l2/pusher.pyx", line 280, in xpra.codecs.v4l2.pusher.Pusher.init_context
    self.init_device(device)
  File "xpra/codecs/v4l2/pusher.pyx", line 317, in xpra.codecs.v4l2.pusher.Pusher.init_device
    assert r>=0, "VIDIOC_S_FMT ioctl failed on %s" % self.device_name
AssertionError: VIDIOC_S_FMT ioctl failed on /dev/video2
2018-05-08 20:51:03,031 Error: cannot start webcam forwarding
2018-05-08 20:51:03,031  all devices failed
2018-05-08 20:51:03,031  /dev/video2 : VIDIOC_S_FMT ioctl failed on /dev/video2
2018-05-08 20:51:03,031 stop_all_virtual_webcams() stopping: {}

API docs:

• ioctl VIDIOC_G_FMT, VIDIOC_S_FMT, VIDIOC_TRY_FMT
• v4l2_pix_format

[totaam]

2018-05-13 18:22:22: antoine commented

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This is an upstream bug: Invalid IOCTL call in 4.16

[totaam]

2018-06-05 17:30:27: antoine commented

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The fix has been merged upstream: Use kernel-version to determine whether we should set vfl_dir