{"id":25454,"url":"https://patchwork.libcamera.org/api/covers/25454/?format=json","web_url":"https://patchwork.libcamera.org/cover/25454/","project":{"id":1,"url":"https://patchwork.libcamera.org/api/projects/1/?format=json","name":"libcamera","link_name":"libcamera","list_id":"libcamera_core","list_email":"libcamera-devel@lists.libcamera.org","web_url":"","scm_url":"","webscm_url":""},"msgid":"<20251210133704.2711629-1-barnabas.pocze@ideasonboard.com>","date":"2025-12-10T13:37:02","name":"[RFC,v1,0/2] libcamera: pipeline: uvcvideo: FrameDurationLimits","submitter":{"id":216,"url":"https://patchwork.libcamera.org/api/people/216/?format=json","name":"Barnabás Pőcze","email":"barnabas.pocze@ideasonboard.com"},"mbox":"https://patchwork.libcamera.org/cover/25454/mbox/","series":[{"id":5648,"url":"https://patchwork.libcamera.org/api/series/5648/?format=json","web_url":"https://patchwork.libcamera.org/project/libcamera/list/?series=5648","date":"2025-12-10T13:37:02","name":"libcamera: pipeline: uvcvideo: FrameDurationLimits","version":1,"mbox":"https://patchwork.libcamera.org/series/5648/mbox/"}],"comments":"https://patchwork.libcamera.org/api/covers/25454/comments/","headers":{"Return-Path":"","X-Original-To":"parsemail@patchwork.libcamera.org","Delivered-To":"parsemail@patchwork.libcamera.org","Received":["from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id CD778C3257\n\tfor ;\n\tWed, 10 Dec 2025 13:37:11 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id F2BBF61475;\n\tWed, 10 Dec 2025 14:37:10 +0100 (CET)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id A8E08613CB\n\tfor ;\n\tWed, 10 Dec 2025 14:37:09 +0100 (CET)","from pb-laptop.local (185.221.143.114.nat.pool.zt.hu\n\t[185.221.143.114])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 021D66DC\n\tfor ;\n\tWed, 10 Dec 2025 14:37:06 +0100 (CET)"],"Authentication-Results":"lancelot.ideasonboard.com; dkim=pass (1024-bit key;\n\tunprotected) header.d=ideasonboard.com header.i=@ideasonboard.com\n\theader.b=\"mQBCUMAJ\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1765373827;\n\tbh=PaHng9z1B9Te7XfEl6Nk0sA+FRDToKieTnpdYZGMxUw=;\n\th=From:To:Subject:Date:From;\n\tb=mQBCUMAJBx2IOOA3Ezs5HB8+hvdHwB+XrnfPczBJg3rz/FyhPyIwm6oifR6JzlNOh\n\tRVTIIIhoOeIr997GlQOlOmzqXeBd1RYKVgtVfnz2aZsKIWqKA0RPmizYjE1GgPgQdR\n\tltumQiyh8dUhFbVPcqt97eisydUmlq6x1F7htfyc=","From":"=?utf-8?q?Barnab=C3=A1s_P=C5=91cze?= ","To":"libcamera-devel@lists.libcamera.org","Subject":"[RFC PATCH v1 0/2] libcamera: pipeline: uvcvideo:\n\tFrameDurationLimits","Date":"Wed, 10 Dec 2025 14:37:02 +0100","Message-ID":"<20251210133704.2711629-1-barnabas.pocze@ideasonboard.com>","X-Mailer":"git-send-email 2.52.0","MIME-Version":"1.0","Content-Type":"text/plain; charset=UTF-8","Content-Transfer-Encoding":"8bit","X-BeenThere":"libcamera-devel@lists.libcamera.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "},"content":"This patch set tries to add at least some kind of support for setting a frame\nduration on uvc camera to address https://gitlab.freedesktop.org/camera/libcamera/-/issues/296\n\nThe mismatches in the kernel and libcamera interfaces are elaborated in the last patch.\n\nA couple points remain:\n\n(a) Since the frame interval cannot be set during streaming, could this indicate that a\n \"startup control\" concept would be useful in libcamera, where cameras could mark\n certain controls in their `ControlInfoMap` to indicate that they can only be set\n when passed to `Camera::start()`?\n\n(B) I originally intended to advertise all available discrete options in the `ControlInfo`.\n For example:\n\n $ v4l2-ctl --list-formats-ext\n ioctl: VIDIOC_ENUM_FMT\n \tType: Video Capture\n\n \t[0]: 'YUYV' (YUYV 4:2:2)\n \t\tSize: Discrete 640x480\n \t\t\tInterval: Discrete 0.033s (30.000 fps)\n \t\t\tInterval: Discrete 0.040s (25.000 fps)\n \t\t\tInterval: Discrete 0.050s (20.000 fps)\n \t\t\tInterval: Discrete 0.067s (15.000 fps)\n \t\t\tInterval: Discrete 0.100s (10.000 fps)\n \t\t\tInterval: Discrete 0.200s (5.000 fps)\n\n would produce:\n\n ControlInfo {\n .min = { 0.033s },\n .max = { 0.200s },\n .values = {\n { 0.033s, 0.033s },\n { 0.040s, 0.040s },\n { 0.050s, 0.050s },\n { 0.067s, 0.067s },\n { 0.100s, 0.100s },\n { 0.200s, 0.200s },\n },\n }\n\n This would be done in order to satisfy two requirements:\n * every item in `ControlInfo::values()` should be of the proper shape and type\n to be directly applicable as the value of the control;\n * the min/max for array like controls (except strings) should denote the min/max\n for any single element in the array.\n\n Unfortunately, there is no constructor of `ControlInfo` that achieves this.\n Would it be useful to add one?\n\n\nBarnabás Pőcze (2):\n libcamera: pipeline: uvcvideo: Report `FrameDuration`\n libcamera: pipeline: uvcvideo: Handle `FrameDurationLimits`\n\n include/libcamera/internal/v4l2_videodevice.h | 5 +\n src/libcamera/pipeline/uvcvideo/uvcvideo.cpp | 72 ++++++++\n src/libcamera/v4l2_videodevice.cpp | 171 ++++++++++++++++++\n 3 files changed, 248 insertions(+)\n\n--\n2.52.0"}