Installed linux 5.4.0-81.91 and verified that it is working. ** Tags removed: verification-needed-focal ** Tags added: verification-done-focal
-- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1932367 Title: Pixel format change broken for Elgato Cam Link 4K Status in linux package in Ubuntu: Triaged Status in linux source package in Bionic: Fix Committed Status in linux source package in Focal: Fix Committed Status in linux source package in Groovy: Fix Committed Status in linux source package in Hirsute: Fix Committed Status in linux source package in Impish: Triaged Bug description: [Impact] The Elgato Cam Link 4K HDMI video capture card reports to support three different pixel formats, where the first format depends on the connected HDMI device. ``` $ v4l2-ctl -d /dev/video0 --list-formats-ext ioctl: VIDIOC_ENUM_FMT Type: Video Capture [0]: 'NV12' (Y/CbCr 4:2:0) Size: Discrete 3840x2160 Interval: Discrete 0.033s (29.970 fps) [1]: 'NV12' (Y/CbCr 4:2:0) Size: Discrete 3840x2160 Interval: Discrete 0.033s (29.970 fps) [2]: 'YU12' (Planar YUV 4:2:0) Size: Discrete 3840x2160 Interval: Discrete 0.033s (29.970 fps) ``` Changing the pixel format to anything besides the first pixel format does not work: ``` $ v4l2-ctl -d /dev/video0 --try-fmt-video pixelformat=YU12 Format Video Capture: Width/Height : 3840/2160 Pixel Format : 'NV12' (Y/CbCr 4:2:0) Field : None Bytes per Line : 3840 Size Image : 12441600 Colorspace : sRGB Transfer Function : Rec. 709 YCbCr/HSV Encoding: Rec. 709 Quantization : Default (maps to Limited Range) Flags : ``` User space applications like VLC might show an error message on the terminal in that case: ``` libv4l2: error set_fmt gave us a different result than try_fmt! ``` Depending on the error handling of the user space applications, they might display a distorted video, because they use the wrong pixel format for decoding the stream. [Fix] The Elgato Cam Link 4K responds to the USB video probe VS_PROBE_CONTROL/VS_COMMIT_CONTROL with a malformed data structure: The second byte contains bFormatIndex (instead of being the second byte of bmHint). The first byte is always zero. The third byte is always 1. The firmware bug was reported to Elgato on 2020-12-01 and it was forwarded by the support team to the developers as feature request. There is no firmware update available since then. The latest firmware for Elgato Cam Link 4K as of 2021-03-23 has MCU 20.02.19 and FPGA 67. Therefore correct the malformed data structure for this device. The change was successfully tested with VLC, OBS, and Chromium using different pixel formats (YUYV, NV12, YU12), resolutions (3840x2160, 1920x1080), and frame rates (29.970 and 59.940 fps). [Test Case] Connect an input device to the Cam Link 4K and try all three pixel formats with VLC: vlc v4l2:///dev/video0 --v4l2-chroma=NV12 vlc v4l2:///dev/video0 --v4l2-chroma=YU12 [Other Info] The fix was reviewed and accepted by the subsystem maintainer and will be included upstream: https://git.linuxtv.org/media_stage.git/commit/?id=4c6e0976295add7f0ed94d276c04a3d6f1ea8f83 Attached a backported patch for Ubuntu. I successfully tested it with Linux 5.11 on Ubuntu 21.04 and Linux 5.8 on Ubuntu 20.10. It should work on older kernel versions as well. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1932367/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
