[{"id":36615,"web_url":"https://patchwork.libcamera.org/comment/36615/","msgid":"<176209776314.2973778.13257764541614463029@ping.linuxembedded.co.uk>","date":"2025-11-02T15:36:03","subject":"Re: [RFC PATCH v3 17/22] guides: pipeline_handler: Document\n\tPipelineHandler::metadataAvailable","submitter":{"id":4,"url":"https://patchwork.libcamera.org/api/people/4/","name":"Kieran Bingham","email":"kieran.bingham@ideasonboard.com"},"content":"Quoting Barnabás Pőcze (2025-10-30 16:58:11)\n> From: Jacopo Mondi \n> \n> Document the new available helpers to accumulate metadata results in\n> Request::metadata and notify applications about metadata availability.\n> \n> Signed-off-by: Jacopo Mondi \n> Signed-off-by: Barnabás Pőcze \n> ---\n> Original: https://patchwork.libcamera.org/patch/22230/\n> \n> changes in v3:\n> * reword some parts\n> ---\n> Documentation/guides/pipeline-handler.rst | 21 +++++++++++++++------\n> 1 file changed, 15 insertions(+), 6 deletions(-)\n> \n> diff --git a/Documentation/guides/pipeline-handler.rst b/Documentation/guides/pipeline-handler.rst\n> index 85d9cc8700..9ec0da01b9 100644\n> --- a/Documentation/guides/pipeline-handler.rst\n> +++ b/Documentation/guides/pipeline-handler.rst\n> @@ -1358,18 +1358,27 @@ and Slot ` classes documentation.\n> .. _Qt Signals and Slots: https://doc.qt.io/qt-6/signalsandslots.html\n> \n> In order to notify applications about the availability of new frames and data,\n> -the ``Camera`` device exposes two ``Signals`` to which applications can connect\n> -to be notified of frame completion events. The ``bufferComplete`` signal serves\n> -to report to applications the completion event of a single ``Stream`` part of a\n> +the ``Camera`` device exposes three ``Signals`` to which applications can\n> +connect to be notified of frame completion and metadata availability events.\n\nEarlier on in the series we just reported 'the following signals'\ninstead of numbering them. But this is fine.\n\n\n> +\n> +The ``metadataAvailable`` signal serves to notify about the availability of\n> +metadata for a particular ``Request``. The ``bufferComplete`` signal serves to\n> +report to applications the completion event of a single ``Stream`` part of a\n> ``Request``, while the ``requestComplete`` signal notifies the completion of all\n> the ``Streams`` and data submitted as part of a request. This mechanism allows\n> implementation of partial request completion, which allows an application to\n> inspect completed buffers associated with the single streams without waiting for\n> all of them to be ready.\n> \n> -The ``bufferComplete`` and ``requestComplete`` signals are emitted by the\n> -``Camera`` device upon notifications received from the pipeline handler, which\n> -tracks the buffers and request completion status.\n> +The ``metadataAvailable``, ``bufferComplete`` and ``requestComplete`` signals\n> +are emitted by the ``Camera`` device upon notifications received from the\n> +pipeline handler, which tracks the metadata, buffers and request completion\n> +status.\n> +\n> +Metadata availability is signalled by the pipeline handlers by calling the\n> +PipelineHandler base class ``metadataAvailable`` function. This function\n> +notifies applications about metadata availability and accumulates metadata\n> +results in the ``Request::metadata()`` list.\n\nReviewed-by: Kieran Bingham \n\n> \n> The single buffer completion notification is implemented by pipeline handlers\n> by :doxy-int:`connecting ` the ``bufferReady`` signal of the\n> -- \n> 2.51.1\n>","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 8D5C3C3241\n\tfor ;\n\tSun, 2 Nov 2025 15:36:08 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id AEF5A60A8B;\n\tSun, 2 Nov 2025 16:36:07 +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 8A1E0606E6\n\tfor ;\n\tSun, 2 Nov 2025 16:36:06 +0100 (CET)","from pendragon.ideasonboard.com\n\t(cpc89244-aztw30-2-0-cust6594.18-1.cable.virginm.net [86.31.185.195])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 267D710D4;\n\tSun, 2 Nov 2025 16:34:14 +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=\"tclUBC3g\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1762097654;\n\tbh=nHfPf/UbsVTdGiy6Tg0AX+yqEydTMjDdsiBNfbEl03U=;\n\th=In-Reply-To:References:Subject:From:Cc:To:Date:From;\n\tb=tclUBC3g91jrY8DIg0/1qFEbeMr3abllxxdhJK8l0DypEZiz3RUqT1U1nFJRKRguE\n\tyh5biq546qvmEvbRn0oZqF+hPh/dX6o6iFKNa+haYN3WNxuIO+VaKgydheByX0V6Ho\n\tohoVz8sXVmK0S9qpY6UNC2EN279JhBCDn+ENA4rM=","Content-Type":"text/plain; charset=\"utf-8\"","MIME-Version":"1.0","Content-Transfer-Encoding":"quoted-printable","In-Reply-To":"<20251030165816.1095180-18-barnabas.pocze@ideasonboard.com>","References":"<20251030165816.1095180-1-barnabas.pocze@ideasonboard.com>\n\t<20251030165816.1095180-18-barnabas.pocze@ideasonboard.com>","Subject":"Re: [RFC PATCH v3 17/22] guides: pipeline_handler: Document\n\tPipelineHandler::metadataAvailable","From":"Kieran Bingham ","Cc":"Jacopo Mondi ","To":"=?utf-8?q?Barnab=C3=A1s_P=C5=91cze?= ,\n\tlibcamera-devel@lists.libcamera.org","Date":"Sun, 02 Nov 2025 15:36:03 +0000","Message-ID":"<176209776314.2973778.13257764541614463029@ping.linuxembedded.co.uk>","User-Agent":"alot/0.9.1","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\" "}}]