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{
    "id": 22258,
    "url": "https://patchwork.libcamera.org/api/1.1/patches/22258/?format=api",
    "web_url": "https://patchwork.libcamera.org/patch/22258/",
    "project": {
        "id": 1,
        "url": "https://patchwork.libcamera.org/api/1.1/projects/1/?format=api",
        "name": "libcamera",
        "link_name": "libcamera",
        "list_id": "libcamera_core",
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    "msgid": "<20241209162747.2961-2-david.plowman@raspberrypi.com>",
    "date": "2024-12-09T16:27:47",
    "name": "[1/1] controls: Add camera synchronisation controls",
    "commit_ref": null,
    "pull_url": null,
    "state": "accepted",
    "archived": false,
    "hash": "49ff45bbdfc7c295fd733b154c0d983fef737de7",
    "submitter": {
        "id": 42,
        "url": "https://patchwork.libcamera.org/api/1.1/people/42/?format=api",
        "name": "David Plowman",
        "email": "david.plowman@raspberrypi.com"
    },
    "delegate": null,
    "mbox": "https://patchwork.libcamera.org/patch/22258/mbox/",
    "series": [
        {
            "id": 4866,
            "url": "https://patchwork.libcamera.org/api/1.1/series/4866/?format=api",
            "web_url": "https://patchwork.libcamera.org/project/libcamera/list/?series=4866",
            "date": "2024-12-09T16:27:47",
            "name": "Camera synchonrisation controls",
            "version": 1,
            "mbox": "https://patchwork.libcamera.org/series/4866/mbox/"
        }
    ],
    "comments": "https://patchwork.libcamera.org/api/patches/22258/comments/",
    "check": "pending",
    "checks": "https://patchwork.libcamera.org/api/patches/22258/checks/",
    "tags": {},
    "headers": {
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        "From": "David Plowman <david.plowman@raspberrypi.com>",
        "To": "libcamera-devel@lists.libcamera.org",
        "Cc": "David Plowman <david.plowman@raspberrypi.com>",
        "Subject": "[PATCH 1/1] controls: Add camera synchronisation controls",
        "Date": "Mon,  9 Dec 2024 16:27:47 +0000",
        "Message-Id": "<20241209162747.2961-2-david.plowman@raspberrypi.com>",
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    },
    "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 <david.plowman@raspberrypi.com>\n---\n src/libcamera/control_ids_core.yaml | 104 ++++++++++++++++++++++++++++\n 1 file changed, 104 insertions(+)",
    "diff": "diff --git a/src/libcamera/control_ids_core.yaml b/src/libcamera/control_ids_core.yaml\nindex d45cf8e5..6d45b757 100644\n--- a/src/libcamera/control_ids_core.yaml\n+++ b/src/libcamera/control_ids_core.yaml\n@@ -971,4 +971,108 @@ controls:\n       description: |\n         Enable or disable the debug 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\".\n+\n+        Sync mode requires all cameras to be running at (as far as possible) the\n+        same fixed framerate, and may continue to make adjustments to keep the\n+        cameras together for the duration of the session.\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+        \\sa SyncReady\n+        \\sa SyncTimer\n+        \\sa SyncFrames\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 client and server have agreed that they will both be synchronised\n+        and that applications should begin consuming frames.\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 that SyncModeServer is\n+        enabled.\n+\n+        \\sa SyncMode\n+        \\sa SyncReady\n+        \\sa SyncTimer\n+\n ...\n",
    "prefixes": [
        "1/1"
    ]
}