{"id":22401,"url":"https://patchwork.libcamera.org/api/patches/22401/?format=json","web_url":"https://patchwork.libcamera.org/patch/22401/","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":"<20241218180310.7824-4-david.plowman@raspberrypi.com>","date":"2024-12-18T18:03:10","name":"[v2,3/3] controls: Add camera synchronisation controls","commit_ref":null,"pull_url":null,"state":"accepted","archived":false,"hash":"72c0eeccc328f4cfa38045026f1eeadd8ff2a5e2","submitter":{"id":42,"url":"https://patchwork.libcamera.org/api/people/42/?format=json","name":"David Plowman","email":"david.plowman@raspberrypi.com"},"delegate":null,"mbox":"https://patchwork.libcamera.org/patch/22401/mbox/","series":[{"id":4913,"url":"https://patchwork.libcamera.org/api/series/4913/?format=json","web_url":"https://patchwork.libcamera.org/project/libcamera/list/?series=4913","date":"2024-12-18T18:03:07","name":"Wall clocks and camera sync","version":2,"mbox":"https://patchwork.libcamera.org/series/4913/mbox/"}],"comments":"https://patchwork.libcamera.org/api/patches/22401/comments/","check":"pending","checks":"https://patchwork.libcamera.org/api/patches/22401/checks/","tags":{},"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 0D2CAC3306\n\tfor ;\n\tWed, 18 Dec 2024 18:03:25 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 047FB680B2;\n\tWed, 18 Dec 2024 19:03:24 +0100 (CET)","from mail-wm1-x32b.google.com (mail-wm1-x32b.google.com\n\t[IPv6:2a00:1450:4864:20::32b])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id DCF70680A2\n\tfor ;\n\tWed, 18 Dec 2024 19:03:19 +0100 (CET)","by mail-wm1-x32b.google.com with SMTP id\n\t5b1f17b1804b1-436249df846so47462965e9.3\n\tfor ;\n\tWed, 18 Dec 2024 10:03:19 -0800 (PST)","from raspberrypi.pitowers.org\n\t([2a00:1098:3142:1f:c68a:6be1:5ba3:eddd])\n\tby smtp.gmail.com with ESMTPSA id\n\t5b1f17b1804b1-43656b01c88sm27927285e9.17.2024.12.18.10.03.16\n\t(version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256);\n\tWed, 18 Dec 2024 10:03:16 -0800 (PST)"],"Authentication-Results":"lancelot.ideasonboard.com; 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\n\tWed, 18 Dec 2024 10:03:18 -0800 (PST)","From":"David Plowman ","To":"libcamera-devel@lists.libcamera.org","Cc":"David Plowman ,\n\tNaushir Patuck ","Subject":"[PATCH v2 3/3] controls: Add camera synchronisation controls","Date":"Wed, 18 Dec 2024 18:03:10 +0000","Message-Id":"<20241218180310.7824-4-david.plowman@raspberrypi.com>","X-Mailer":"git-send-email 2.39.5","In-Reply-To":"<20241218180310.7824-1-david.plowman@raspberrypi.com>","References":"<20241218180310.7824-1-david.plowman@raspberrypi.com>","MIME-Version":"1.0","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":"New controls are added to control the camera \"sync\" algorithm, which\nallows different cameras to synchronise their frames.\n\nSigned-off-by: David Plowman \nReviewed-by: Naushir Patuck \n---\n src/libcamera/control_ids_core.yaml | 109 ++++++++++++++++++++++++++++\n 1 file changed, 109 insertions(+)","diff":"diff --git a/src/libcamera/control_ids_core.yaml b/src/libcamera/control_ids_core.yaml\nindex 8485f7e8..cf502944 100644\n--- a/src/libcamera/control_ids_core.yaml\n+++ b/src/libcamera/control_ids_core.yaml\n@@ -1027,4 +1027,113 @@ controls:\n \n The FrameWallClock control can only be returned in metadata.\n \n+ - SyncMode:\n+ type: int32_t\n+ description: |\n+ Enable or disable camera synchronisation (\"sync\") mode.\n+\n+ When sync mode is enabled, a camera will synchronise frames temporally\n+ with other cameras, either attached to the same device or a different\n+ one. There should be one \"server\" device, which broadcasts timing\n+ information to one or more \"clients\". Communication is one-way, from\n+ server to clients only, and it is only clients that adjust their frame\n+ timings to match the server.\n+\n+ Sync mode requires all cameras to be running at (as far as possible) the\n+ same fixed framerate. Clients may continue to make adjustments to keep\n+ their cameras synchronised with the server for the duration of the\n+ session, though any updates after the initial ones should remain small.\n+\n+ \\sa SyncReady\n+ \\sa SyncTimer\n+ \\sa SyncFrames\n+\n+ enum:\n+ - name: SyncModeOff\n+ value: 0\n+ description: Disable sync mode.\n+ - name: SyncModeServer\n+ value: 1\n+ description: |\n+ Enable sync mode, act as server. The server broadcasts timing\n+ messages to any clients that are listening, so that the clients can\n+ synchronise their camera frames with the server's.\n+ - name: SyncModeClient\n+ value: 2\n+ description: |\n+ Enable sync mode, act as client. A client listens for any server\n+ messages, and arranges for its camera frames to synchronise as\n+ closely as possible with the server's. Many clients can listen out\n+ for the same server. Clients can also be started ahead of any\n+ servers, causing them merely to wait for the server to start.\n+\n+ - SyncReady:\n+ type: bool\n+ description: |\n+ When using the camera synchronisation algorithm, the server broadcasts\n+ timing information to the clients. This also includes the time (some\n+ number of frames in the future, called the \"ready time\") at which the\n+ server will signal its controlling application, using this control, to\n+ start using the image frames.\n+\n+ The client receives the \"ready time\" from the server, and will signal\n+ its application to start using the frames at this same moment.\n+\n+ While this control value is false, applications (on both client and\n+ server) should continue to wait, and not use the frames.\n+\n+ Once this value becomes true, it means that this is the first frame\n+ where the server and its clients have agreed that they will both be\n+ synchronised and that applications should begin consuming frames.\n+ Thereafter, this control will continue to signal the value true for\n+ the rest of the session.\n+\n+ \\sa SyncMode\n+ \\sa SyncTImer\n+ \\sa SyncFrames\n+\n+ - SyncTimer:\n+ type: int64_t\n+ description: |\n+ This reports the amount of time, in microseconds, until the \"ready\n+ time\", at which the server and client will signal their controlling\n+ applications that the frames are now synchronised and should be\n+ used. The value may be refined slightly over time, becoming more precise\n+ as the \"ready time\" approaches.\n+\n+ Servers always report this value, whereas clients will omit this control\n+ until they have received a message from the server that enables them to\n+ calculate it.\n+\n+ Normally the value will start positive (the \"ready time\" is in the\n+ future), and decrease towards zero, before becoming negative (the \"ready\n+ time\" has elapsed). So there should be just one frame where the timer\n+ value is, or is very close to, zero - the one for which the SyncReady\n+ control becomes true. At this moment, the value indicates how closely\n+ synchronised the client believes it is with the server.\n+\n+ But note that if frames are being dropped, then the \"near zero\" valued\n+ frame, or indeed any other, could be skipped. In these cases the timer\n+ value allows an application to deduce that this has happened.\n+\n+ \\sa SyncMode\n+ \\sa SyncReady\n+ \\sa SyncFrames\n+\n+ - SyncFrames:\n+ type: int32_t\n+ description: |\n+ The number of frames the server should wait, after enabling\n+ SyncModeServer, before signalling (via the SyncReady control) that\n+ frames should be used. This therefore determines the \"ready time\" for\n+ all synchronised cameras.\n+\n+ This control value should be set only for the device that is to act as\n+ the server, before or at the same moment at which SyncModeServer is\n+ enabled.\n+\n+ \\sa SyncMode\n+ \\sa SyncReady\n+ \\sa SyncTimer\n+\n ...\n","prefixes":["v2","3/3"]}