Public bug reported: Ubuntu 26.04, v4l2-relayd 0.2.0-0ubuntu1, libcamera 0.7.0, kernel 7.0.0-31-generic. Hardware: Dell XPS 13 9320, IPU6 + ov01a10 MIPI camera, in-tree kernel driver (no intel-ipu6-dkms), libcamera simple pipeline + software ISP.
With VIDEOSRC=libcamerasrc, the relay produces only black frames. Two independent causes: 1. Sandbox blocks the software ISP. [email protected] sets DevicePolicy=closed and allowlists only drm/media/ psys/video4linux. libcamera's SoftISP needs /dev/udmabuf or /dev/dma_heap/*: ERROR DmaBufAllocator dma_buf_allocator.cpp:119 Could not open any dma-buf provider ERROR SoftwareIsp software_isp.cpp:88 Failed to create DmaBufAllocator object WARN SimplePipeline simple.cpp:620 Failed to create software ISP, disabling software debayering The allowlist (note the psys entries) predates the SoftISP path. Fix: add DeviceAllow=/dev/udmabuf rw DeviceAllow=/dev/dma_heap/system rw 2. FORMAT=YUY2 can never negotiate with libcamerasrc. The SoftISP outputs only RGB formats (here RGBA/ABGR8888 etc., verified with cam -I), and the relay applies FORMAT directly to libcamerasrc's caps with no conversion, so the pipeline fails instantly: gst_libcamera_src_task_enter (): streaming stopped, reason not- negotiated (-4) Reproducible standalone; even matching libcamerasrc's own negotiated caps verbatim fails when set as a fixed capsfilter: gst-launch-1.0 libcamerasrc ! video/x-raw,format=RGBA,width=1280,height=800,colorimetry=sRGB,framerate=30/1 ! fakesink while unconstrained negotiation works: gst-launch-1.0 libcamerasrc ! videoconvert ! fakesink -> caps = video/x-raw, format=RGBA, 1280x800, sRGB, 30/1 The relay pipeline needs a videoconvert between source and the appsrc caps (or equivalent) for the libcamerasrc case. Net effect: on the default-supported MIPI camera path (in-tree IPU6 + libcamera), v4l2-relayd delivers black frames out of the box. A plain gst-launch-1.0 libcamerasrc ! videoconvert ! queue ! v4l2sink device=/dev/videoN into the same v4l2loopback device works, confirming the stack itself is fine. Also worth noting: the shipped default VIDEOSRC=videotestsrc means the libcamerasrc path gets no coverage in a default install. ProblemType: Bug DistroRelease: Ubuntu 26.04 Package: v4l2-relayd 0.2.0-0ubuntu1 ProcVersionSignature: Ubuntu 7.0.0-31.31-generic 7.0.14 Uname: Linux 7.0.0-31-generic x86_64 ApportVersion: 2.34.1-0ubuntu0.1 Architecture: amd64 CasperMD5CheckResult: pass CurrentDesktop: ubuntu:GNOME Date: Sun Sep 6 12:00:18 2026 DistributionChannelDescriptor: # This is the distribution channel descriptor for the OEM CDs # For more information see http://wiki.ubuntu.com/DistributionChannelDescriptor canonical-oem-somerville-jammy-amd64-20220504-33 InstallationDate: Installed on 2023-08-25 (1108 days ago) InstallationMedia: Ubuntu 22.04 LTS "Jammy Jellyfish" - somerville-jammy-amd64-20220504-33 ProcEnviron: LANG=en_US.UTF-8 PATH=(custom, no user) SHELL=/bin/bash TERM=xterm-256color XDG_RUNTIME_DIR=<set> SourcePackage: v4l2-relayd UpgradeStatus: Upgraded to resolute on 2026-06-10 (88 days ago) mtime.conffile..etc.default.v4l2-relayd: 2026-09-06T11:24:43.009736 ** Affects: v4l2-relayd (Ubuntu) Importance: Undecided Status: New ** Tags: amd64 apport-bug resolute wayland-session -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2166611 Title: v4l2-relayd unusable with libcamerasrc/SoftISP: sandbox blocks dma-buf allocator, and YUY2 caps never negotiate (black frames) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/v4l2-relayd/+bug/2166611/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
