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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <72B7F2AA-4FCC-4842-A80B-5C4D856C0A89@gmx.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:Sa+IbVrkpE8FpeYqzNyR/0p5WAdgqupCaLDEDxHLWt6+luaiWmi A/OsEcpY1AB4s1G00XHdQ262SDKvl+vpudFA8ZcCmtmeCqrcrHhQLI5ZAIxIACnoLnQfCy+ PjKEwin8/2eAwQp0rcy5Nso5QQTvOjSjUlpZC5vDQYgONvZRnga52ivPriFP7crBPso7kga nVIAx+wHMvFCY85QfMQhw== X-UI-Out-Filterresults: notjunk:1;V03:K0:K6MqXWV+Fx0=:JEaNs4j2YtkRa38rA/xh4m O38t59w+vdQRT2s+EfvJZuZSC+mwIYdtlLJjyYIFduafO/B+qdfxIrzodc+0FxjCRhBTwF5+k ZUr91+EddbWTjDOsXjiYz2bTsyP4thcpiYby3HgOk+UwXjznuWnPsAvMLSNr2lqCW10q/qHXc A81oxYQe5KRAdDkAM1IDG38bcIvflMsfNJ+4k8Otav5g+QXPzwQYeP2B7GTsVn7ORoSEcFysz WLelA8lFQPNWexqkwiblSJKJKqJ8+XiB3sdVA8lSrLl2y0WK31iKAFS8S8OmIvSS118hA4SrE 2VDReJzJ16hJGwc9KU01XtOWIJhm625XlyKLVufk4aCx8OyYrtbTxXGR+JJ9O+YvxCLqKprrp AsLdBJMExytDEHiY/CGdjrxNizx/bmb+KDpeDnWCSmwsogkBcACJjENl+Oaakei2ARO1SV8kc OA7nO5lucSFz8RL7TzQIP58ziUzTmXeh+yGW6GHsoAXe8m3tqv1oqSQfVMozeynX1XbxXeemo B0/4OSs5MiXh/3cwJQ3zjnzzF35bnHjN1ZklievsodwErr+VVzraHt22KkaMBz+emHERjBLoH 7Iw8Z1a0oiBkGoqMQnld6eefzS/DoARbSXQWa8aFxVjDuzZud7KXSJEFXvtgR4VFZMFu2xBg9 dAPcBkWr9OcvYeiOrI0DpRYkz8du1dGr3TT0tD5U447xthH6jiMAVziMlOtDquedyNeqlvYko ILngR9P+EMncOpfbZS5RqNhSVTXkF28j+K9UJnGPgQn71GymDWkbBBqM3PV+jG5IitS+hKOxR Qt9NxxkKEbvL4X1gIqKfxGFeDWJB8BSB4X4n+61zGuvf92qtCYp2Oa1DBF/FafYweNsvJ1Yjj 9VODrI5UkPe87rSBK4ritNCSHueMbJypVm5sYQdn4Hx19GtsUpCiUgUSZ2RvqWfH7Z+puCOUu nFLMxJ9vuRTQ2da5yzPz6th9H0l1JrmbJ2fGylVRaM/02UL2XpheihfGzDdtU2RH8D53bvKhY EqdVVwa38ah+lFiZpuAwrCan2Vgqaga9q9iHg9FJTQXg3IrwvNESKTNRYNsv8zOlTs6lub+0F k1FKuwPes8CYL5qATd4rA8TZNWTPwv25x2nTkPrXNbUy7+Duln/dQ6YD9G6yT/4hmXEWORNmN m5ykbDl/Kci6KyknSK6Mgrv443lO3g1lb9ppb/h/WwwuiIFnXdL5dk0ZBHesiATaV8AXkDbg6 VtHJH5eQG0Rb9+BqS Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org Hello, Just in case someone should stumble across this thread: An appropriate solution is available here: https://github.com/xkahn/camlink As pointed out by Hans before the described problem is technically an application bug, so one might say it should be fixed on application level, which is what the solution above does. Best, Stefan On 17.08.20 16:50, Stefan Witzel wrote: > Hi Hans, > > I suppose it is ultimately an application bug. I was just hoping that th= e v4l driver cold somehow artificially restrict the device's feature list = so as to make the buggy application (which seems to be pretty much any exi= sting web conference app) work. That would be like the hardware workaround= but on driver level. > > I do not yet have the device myself, so I'm relying on information from = the website I quoted. I very much appreciate that you took the time to rep= ly! I might come back with more concrete questions once I have the device. > > Thanks a lot! Best, > Stefan > > Am 17. August 2020 15:34:00 MESZ schrieb Hans Verkuil : >> On 17/08/2020 14:09, Stefan Witzel wrote: >>> Hello, >>> >>> I am not a V4L developer so if this is not the right place to bring >> up >>> the issue please tell me who to contact instead. >>> The page [1] documents a problem with a particular device "Elgato Cam >>> Link 4K" which provides various format options among which most >> software >>> does not consciously pick the one which it implicitly expects leading >> to >>> problems. There is a software workaround, transcoding and looping >>> through a virtual device and a hardware fix flashing the problematic >>> profiles away. >>> However it appears to me that the most satisfactory solution is >> hinted >>> at in the sentence >>> >>>> I couldn't find any option in V4L to force selection of 'YUYV >> 4:2:2', so instead >>> >>> So my question is: what changes would be necessary to allow v4l2-ctl >> to >>> enforce a particular format and who would be the right person to ask >> to >>> make such changes? >> >> It's there already: >> >> v4l2-ctl -v pixelformat=3DYUYV >> >> That will do the trick. >> >> If you plug in the device and run 'v4l2-ctl -V', which pixelformat does >> it >> report? I would expect it to be YUYV since that's first in the list. >> >> If apps like Discord pick YU12 instead, then that's weird. That's >> something that >> the application does, and v4l2-ctl won't help with that. I.e., it >> appears to be >> an application bug. >> >> One other alternative is that the device has broken 4:2:0 support, i.e. >> it reports >> these formats, but they don't actually work. You can use qv4l2 or >> qvidcap to test >> if these 4:2:0 formats are working. >> >> Regards, >> >> Hans >> >> >>> >>> Best regards, >>> Stefan >>> >>> >>> [1] >> https://assortedhackery.com/patching-cam-link-to-play-nicer-on-linux/ >>>