From patchwork Tue Jan 6 16:57:49 2026 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Barnab=C3=A1s_P=C5=91cze?= X-Patchwork-Id: 25646 Return-Path: X-Original-To: parsemail@patchwork.libcamera.org Delivered-To: parsemail@patchwork.libcamera.org Received: from lancelot.ideasonboard.com (lancelot.ideasonboard.com [92.243.16.209]) by patchwork.libcamera.org (Postfix) with ESMTPS id 753ADC32C1 for ; Tue, 6 Jan 2026 16:58:19 +0000 (UTC) Received: from lancelot.ideasonboard.com (localhost [IPv6:::1]) by lancelot.ideasonboard.com (Postfix) with ESMTP id 0FECB61FF1; Tue, 6 Jan 2026 17:58:16 +0100 (CET) Authentication-Results: lancelot.ideasonboard.com; dkim=pass (1024-bit key; unprotected) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="UiKnDtTf"; dkim-atps=neutral Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647]) by lancelot.ideasonboard.com (Postfix) with ESMTPS id 81CE361FD4 for ; Tue, 6 Jan 2026 17:58:02 +0100 (CET) Received: from pb-laptop.local (185.221.143.114.nat.pool.zt.hu [185.221.143.114]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 38EDF82A; Tue, 6 Jan 2026 17:57:41 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1767718661; bh=++AuruAGHo/40XDNE7QMmVlClER48RxnXnpxx18i1rc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UiKnDtTf2qHk0hagwS+sg+Fk9TpW5iM6hBCFDWKFpo0nDQ1Po5b/yin2o2F8iDG9g /bt6qjsejCm6oCAYELUEVvhvmwQ9m8Uuvh/hP2SJzYdVx0zmUZadZ62B9LTJ561bJU 02pwgECQ82QFU23ijGmK/XndGAbcR5sT1UV+CCYY= From: =?utf-8?q?Barnab=C3=A1s_P=C5=91cze?= To: libcamera-devel@lists.libcamera.org Cc: Jacopo Mondi , Kieran Bingham Subject: [PATCH v4 17/22] guides: pipeline_handler: Document PipelineHandler::metadataAvailable Date: Tue, 6 Jan 2026 17:57:49 +0100 Message-ID: <20260106165754.1759831-18-barnabas.pocze@ideasonboard.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260106165754.1759831-1-barnabas.pocze@ideasonboard.com> References: <20260106165754.1759831-1-barnabas.pocze@ideasonboard.com> MIME-Version: 1.0 X-BeenThere: libcamera-devel@lists.libcamera.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: libcamera-devel-bounces@lists.libcamera.org Sender: "libcamera-devel" From: Jacopo Mondi Document the new available helpers to accumulate metadata results in Request::metadata and notify applications about metadata availability. Signed-off-by: Jacopo Mondi Signed-off-by: Barnabás Pőcze Reviewed-by: Kieran Bingham --- Original: https://patchwork.libcamera.org/patch/22230/ changes in v3: * reword some parts --- Documentation/guides/pipeline-handler.rst | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-) diff --git a/Documentation/guides/pipeline-handler.rst b/Documentation/guides/pipeline-handler.rst index 85d9cc870..9ec0da01b 100644 --- a/Documentation/guides/pipeline-handler.rst +++ b/Documentation/guides/pipeline-handler.rst @@ -1358,18 +1358,27 @@ and Slot ` classes documentation. .. _Qt Signals and Slots: https://doc.qt.io/qt-6/signalsandslots.html In order to notify applications about the availability of new frames and data, -the ``Camera`` device exposes two ``Signals`` to which applications can connect -to be notified of frame completion events. The ``bufferComplete`` signal serves -to report to applications the completion event of a single ``Stream`` part of a +the ``Camera`` device exposes three ``Signals`` to which applications can +connect to be notified of frame completion and metadata availability events. + +The ``metadataAvailable`` signal serves to notify about the availability of +metadata for a particular ``Request``. The ``bufferComplete`` signal serves to +report to applications the completion event of a single ``Stream`` part of a ``Request``, while the ``requestComplete`` signal notifies the completion of all the ``Streams`` and data submitted as part of a request. This mechanism allows implementation of partial request completion, which allows an application to inspect completed buffers associated with the single streams without waiting for all of them to be ready. -The ``bufferComplete`` and ``requestComplete`` signals are emitted by the -``Camera`` device upon notifications received from the pipeline handler, which -tracks the buffers and request completion status. +The ``metadataAvailable``, ``bufferComplete`` and ``requestComplete`` signals +are emitted by the ``Camera`` device upon notifications received from the +pipeline handler, which tracks the metadata, buffers and request completion +status. + +Metadata availability is signalled by the pipeline handlers by calling the +PipelineHandler base class ``metadataAvailable`` function. This function +notifies applications about metadata availability and accumulates metadata +results in the ``Request::metadata()`` list. The single buffer completion notification is implemented by pipeline handlers by :doxy-int:`connecting ` the ``bufferReady`` signal of the