Dear Maintainer,

Under Debian 10 rc1, when I plug in my USB camera (the very common logitech
c930e), 2 devices are added (e.g. /dev/video0 and /dev/video1).

v4l-info works on /dev/video0, but fails on /dev/video1
(VIDIOC_G_FMT(VIDEO_CAPTURE): Invalid argument). When I try to access the
device using gstreamer it tells me that /dev/video1 is not a capture device.

In stretch I don't see this behavior.

Attached are syslog, dmesg, v4l-info for both devices, udevadm for both
devices, lsusb, lspci.

Let me know if any other logs can be of help.

This is the feature added in commit 088ead25524583e2200aa99111bea2f66a86545a.

    media: uvcvideo: Add a metadata device node

    Some UVC video cameras contain metadata in their payload headers. This
    patch extracts that data, adding more clock synchronisation information,
    on both bulk and isochronous endpoints and makes it available to the user
    space on a separate video node, using the V4L2_CAP_META_CAPTURE capability
    and the V4L2_BUF_TYPE_META_CAPTURE buffer queue type. By default, only the
    V4L2_META_FMT_UVC pixel format is available from those nodes. However,
    cameras can be added to the device ID table to additionally specify their
    own metadata format, in which case that format will also become available
    from the metadata node.

Guennadi, sorry but this feels more like a bug than a feature to me, and at
least three other people have reported it as a bug without working out the cause.

* https://bugs.debian.org/930860
* https://bugzilla.kernel.org/show_bug.cgi?id=199193
* https://bugzilla.kernel.org/show_bug.cgi?id=199575

Seba, thanks for reporting this. I met this feature while working on a
closed-source application, added a workaround to ignore cameras that don't
support normal video capture, and haven't yet got round to replying to the
Bugzilla reports above. I'd be happy if someone else took on that task.

BR,
Steve

Thanks Steve. I replied to the bugzilla reports you listed.
A google search on that commit number reveals quite a few more similar bug
reports and applications breaking because of it.
I guess quite a few applications would not be aware of the existence of
these metadata nodes.
Anyway, I'll also work around it in the same way you did.


Op za 22 jun. 2019 om 02:30 schreef Steve Cotton <steve@s.cotton.clara.co.uk

This seems to be expected behaviour, at this point.

hdmi2usb-udev doesn't handle it in buster, and it needs to to be useful.

SR

We believe that the bug you reported is fixed in the latest version of
hdmi2usb-mode-switch, which is due to be installed in the Debian FTP archive.

A summary of the changes between this version and the previous one is
attached.

Thank you for reporting the bug, which will now be closed.  If you
have further comments please address them to 1011938@bugs.debian.org,
and the maintainer will reopen the bug report if appropriate.

Debian distribution maintenance software
pp.
Stefano Rivera <stefanor@debian.org> (supplier of updated hdmi2usb-mode-switch package)

(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing ftpmaster@ftp-master.debian.org)
Format: 1.8
Date: Fri, 27 May 2022 12:13:39 +0200
Source: hdmi2usb-mode-switch
Architecture: source
Version: 0.0.1-3
Distribution: unstable
Urgency: low
Maintainer: Stefano Rivera <stefanor@debian.org>
Changed-By: Stefano Rivera <stefanor@debian.org>
Closes: 1011938
Changes:
 hdmi2usb-mode-switch (0.0.1-3) unstable; urgency=low
 .
   [ Debian Janitor ]
   * Bump debhelper from deprecated 9 to 12.
   * Set debhelper-compat version in Build-Depends.
   * Set upstream metadata fields: Bug-Database, Bug-Submit, Repository,
     Repository-Browse.
   * Use canonical URL in Vcs-Git.
   * Apply multi-arch hints.
     + hdmi2usb-udev: Add Multi-Arch: foreign.
   * Remove constraints unnecessary since buster:
     + hdmi2usb-mode-switch: Drop versioned constraint on ixo-usb-jtag and
       openocd in Depends.
 .
   [ Stefano Rivera ]
   * Bump debhelper from old 12 to 13.
   * Update watch file format version to 4.
   * Declare: Rules-Requires-Root: no.
   * Bump Standards-Version to 4.6.1, no changes needed.
   * Bump copyright years.
   * Patch: Udev: Add a suffix to /dev/video device nodes to disambiguate them.
     (Closes: #1011938)
   * Move udev rules to priority 70, to come after 60-persistent-v4l.rules.
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We believe that the bug you reported is fixed in the latest version of
hdmi2usb-mode-switch, which is due to be installed in the Debian FTP archive.

A summary of the changes between this version and the previous one is
attached.

Thank you for reporting the bug, which will now be closed.  If you
have further comments please address them to 1011938@bugs.debian.org,
and the maintainer will reopen the bug report if appropriate.

Debian distribution maintenance software
pp.
Stefano Rivera <stefanor@debian.org> (supplier of updated hdmi2usb-mode-switch package)

(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing ftpmaster@ftp-master.debian.org)
Format: 1.8
Date: Fri, 27 May 2022 12:22:19 +0200
Source: hdmi2usb-mode-switch
Architecture: source
Version: 0.0.1-2+deb11u1
Distribution: bullseye
Urgency: low
Maintainer: Stefano Rivera <stefanor@debian.org>
Changed-By: Stefano Rivera <stefanor@debian.org>
Closes: 1011938
Changes:
 hdmi2usb-mode-switch (0.0.1-2+deb11u1) bullseye; urgency=low
 .
   * Patch: Udev: Add a suffix to /dev/video device nodes to disambiguate them.
     (Closes: #1011938)
   * Move udev rules to priority 70, to come after 60-persistent-v4l.rules.
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