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{
    "id": 14215,
    "url": "https://patchwork.libcamera.org/api/1.1/patches/14215/?format=api",
    "web_url": "https://patchwork.libcamera.org/patch/14215/",
    "project": {
        "id": 1,
        "url": "https://patchwork.libcamera.org/api/1.1/projects/1/?format=api",
        "name": "libcamera",
        "link_name": "libcamera",
        "list_id": "libcamera_core",
        "list_email": "libcamera-devel@lists.libcamera.org",
        "web_url": "",
        "scm_url": "",
        "webscm_url": ""
    },
    "msgid": "<20211020154607.180161-9-jeanmichel.hautbois@ideasonboard.com>",
    "date": "2021-10-20T15:46:02",
    "name": "[libcamera-devel,v2,08/13] ipa: ipu3: agc: Simplify division of exposure/gain",
    "commit_ref": null,
    "pull_url": null,
    "state": "superseded",
    "archived": false,
    "hash": "fbf12f4b416ea8aac7aeb69ba8d73a46a97e017b",
    "submitter": {
        "id": 75,
        "url": "https://patchwork.libcamera.org/api/1.1/people/75/?format=api",
        "name": "Jean-Michel Hautbois",
        "email": "jeanmichel.hautbois@ideasonboard.com"
    },
    "delegate": null,
    "mbox": "https://patchwork.libcamera.org/patch/14215/mbox/",
    "series": [
        {
            "id": 2645,
            "url": "https://patchwork.libcamera.org/api/1.1/series/2645/?format=api",
            "web_url": "https://patchwork.libcamera.org/project/libcamera/list/?series=2645",
            "date": "2021-10-20T15:45:54",
            "name": "ipa: ipu3: Fix AGC bugs",
            "version": 2,
            "mbox": "https://patchwork.libcamera.org/series/2645/mbox/"
        }
    ],
    "comments": "https://patchwork.libcamera.org/api/patches/14215/comments/",
    "check": "pending",
    "checks": "https://patchwork.libcamera.org/api/patches/14215/checks/",
    "tags": {},
    "headers": {
        "Return-Path": "<libcamera-devel-bounces@lists.libcamera.org>",
        "X-Original-To": "parsemail@patchwork.libcamera.org",
        "Delivered-To": "parsemail@patchwork.libcamera.org",
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            "from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id 57CE9BDB1C\n\tfor <parsemail@patchwork.libcamera.org>;\n\tWed, 20 Oct 2021 15:46:24 +0000 (UTC)",
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        "From": "Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>",
        "To": "libcamera-devel@lists.libcamera.org",
        "Date": "Wed, 20 Oct 2021 17:46:02 +0200",
        "Message-Id": "<20211020154607.180161-9-jeanmichel.hautbois@ideasonboard.com>",
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        "In-Reply-To": "<20211020154607.180161-1-jeanmichel.hautbois@ideasonboard.com>",
        "References": "<20211020154607.180161-1-jeanmichel.hautbois@ideasonboard.com>",
        "MIME-Version": "1.0",
        "Content-Transfer-Encoding": "8bit",
        "Subject": "[libcamera-devel] [PATCH v2 08/13] ipa: ipu3: agc: Simplify\n\tdivision of exposure/gain",
        "X-BeenThere": "libcamera-devel@lists.libcamera.org",
        "X-Mailman-Version": "2.1.29",
        "Precedence": "list",
        "List-Id": "<libcamera-devel.lists.libcamera.org>",
        "List-Unsubscribe": "<https://lists.libcamera.org/options/libcamera-devel>,\n\t<mailto:libcamera-devel-request@lists.libcamera.org?subject=unsubscribe>",
        "List-Archive": "<https://lists.libcamera.org/pipermail/libcamera-devel/>",
        "List-Post": "<mailto:libcamera-devel@lists.libcamera.org>",
        "List-Help": "<mailto:libcamera-devel-request@lists.libcamera.org?subject=help>",
        "List-Subscribe": "<https://lists.libcamera.org/listinfo/libcamera-devel>,\n\t<mailto:libcamera-devel-request@lists.libcamera.org?subject=subscribe>",
        "Errors-To": "libcamera-devel-bounces@lists.libcamera.org",
        "Sender": "\"libcamera-devel\" <libcamera-devel-bounces@lists.libcamera.org>"
    },
    "content": "Until now, the algorithm makes complex assumptions when dividing the\nexposure and analogue gain values. Instead, use a simpler clamping of\nthe shutter speed first, and then of the analogue gain, based on the\nlimits configured.\n\nWhile at it, correct a bug which makes the algorithm not use the\nfiltered result from filterExposure().\n\nSigned-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>\n---\n src/ipa/ipu3/algorithms/agc.cpp | 36 +++++++++++++++++----------------\n 1 file changed, 19 insertions(+), 17 deletions(-)",
    "diff": "diff --git a/src/ipa/ipu3/algorithms/agc.cpp b/src/ipa/ipu3/algorithms/agc.cpp\nindex 1bae1eb9..84e41834 100644\n--- a/src/ipa/ipu3/algorithms/agc.cpp\n+++ b/src/ipa/ipu3/algorithms/agc.cpp\n@@ -146,7 +146,9 @@ void Agc::lockExposureGain(uint32_t &exposure, double &gain)\n \t\t\t\t    << \" Gain \" << gain;\n \n \t\tcurrentExposure_ = currentExposureNoDg_ * newGain;\n+\t\tutils::Duration minShutterSpeed = minExposureLines_ * lineDuration_;\n \t\tutils::Duration maxShutterSpeed = maxExposureLines_ * lineDuration_;\n+\n \t\tutils::Duration maxTotalExposure = maxShutterSpeed * kMaxGain;\n \t\tcurrentExposure_ = std::min(currentExposure_, maxTotalExposure);\n \t\tLOG(IPU3Agc, Debug) << \"Target total exposure \" << currentExposure_\n@@ -155,23 +157,23 @@ void Agc::lockExposureGain(uint32_t &exposure, double &gain)\n \t\t/* \\todo: estimate if we need to desaturate */\n \t\tfilterExposure();\n \n-\t\tutils::Duration newExposure = 0.0s;\n-\t\tif (currentShutter < maxShutterSpeed) {\n-\t\t\texposure = std::clamp<uint32_t>(exposure * currentExposure_ / currentExposureNoDg_,\n-\t\t\t\t\t\t\tminExposureLines_,\n-\t\t\t\t\t\t\tmaxExposureLines_);\n-\t\t\tnewExposure = currentExposure_ / exposure;\n-\t\t\tgain = std::clamp(gain * currentExposure_ / newExposure,\n-\t\t\t\t\t  kMinGain, kMaxGain);\n-\t\t} else if (currentShutter >= maxShutterSpeed) {\n-\t\t\tgain = std::clamp(gain * currentExposure_ / currentExposureNoDg_,\n-\t\t\t\t\t  kMinGain, kMaxGain);\n-\t\t\tnewExposure = currentExposure_ / gain;\n-\t\t\texposure = std::clamp<uint32_t>(exposure * currentExposure_ / newExposure,\n-\t\t\t\t\t\t\tminExposureLines_,\n-\t\t\t\t\t\t\tmaxExposureLines_);\n-\t\t}\n-\t\tLOG(IPU3Agc, Debug) << \"Adjust exposure \" << exposure * lineDuration_ << \" and gain \" << gain;\n+\t\tutils::Duration exposureValue = filteredExposure_;\n+\t\tutils::Duration shutterTime = minShutterSpeed;\n+\n+\t\t/*\n+\t\t * Push the shutter time up to the maximum first, and only then\n+\t\t * increase the gain.\n+\t\t */\n+\t\tshutterTime = std::clamp<utils::Duration>(exposureValue / kMinGain,\n+\t\t\t\t\t\t\t  minShutterSpeed, maxShutterSpeed);\n+\t\tdouble stepGain = std::clamp(exposureValue / shutterTime,\n+\t\t\t\t\t     kMinGain, kMaxGain);\n+\t\tLOG(IPU3Agc, Debug) << \"Divided up shutter and gain are \"\n+\t\t\t\t    << shutterTime << \" and \"\n+\t\t\t\t    << stepGain;\n+\n+\t\texposure = shutterTime / lineDuration_;\n+\t\tgain = stepGain;\n \t}\n \tlastFrame_ = frameCount_;\n }\n",
    "prefixes": [
        "libcamera-devel",
        "v2",
        "08/13"
    ]
}