[{"id":37499,"web_url":"https://patchwork.libcamera.org/comment/37499/","msgid":"<176771495548.112111.12971944340047876740@isaac-ThinkPad-T16-Gen-2>","date":"2026-01-06T15:55:55","subject":"Re: [PATCH 01/11] libcamera: Infrastructure to ask for \"memory\"\n\tcameras","submitter":{"id":215,"url":"https://patchwork.libcamera.org/api/people/215/","name":"Isaac Scott","email":"isaac.scott@ideasonboard.com"},"content":"Hi David,\n\nThank you for the patch!\n\nQuoting David Plowman (2025-12-10 16:15:16)\n> \"Memory\" cameras are used to make it easier to process raw camera\n> images that are stored in memory buffers. There may be no actual\n> camera attached to the system at all.\n> \n> Memory cameras are not created when the system starts. Depending on\n> the pipeline handler, it may be possible to open many memory cameras\n> simultaneously, or none at all. So any time an application requests a\n> memory camera, we check with the pipeline handler whether it can\n> provide one.\n> \n> Signed-off-by: David Plowman \n> ---\n> include/libcamera/camera_manager.h | 4 ++\n> include/libcamera/internal/camera_manager.h | 5 ++\n> include/libcamera/internal/pipeline_handler.h | 8 +++\n> src/libcamera/camera_manager.cpp | 64 +++++++++++++++++++\n> src/libcamera/pipeline_handler.cpp | 23 +++++++\n> 5 files changed, 104 insertions(+)\n> \n> diff --git a/include/libcamera/camera_manager.h b/include/libcamera/camera_manager.h\n> index 27835500..436db409 100644\n> --- a/include/libcamera/camera_manager.h\n> +++ b/include/libcamera/camera_manager.h\n> @@ -7,6 +7,7 @@\n> \n> #pragma once\n> \n> +#include \n> #include \n> #include \n> #include \n> @@ -20,6 +21,7 @@\n> namespace libcamera {\n> \n> class Camera;\n> +class PipelineHandler;\n> \n> class CameraManager : public Object, public Extensible\n> {\n> @@ -33,6 +35,8 @@ public:\n> \n> std::vector> cameras() const;\n> std::shared_ptr get(std::string_view id);\n> + std::vector memoryCameras() const;\n> + std::shared_ptr getMemoryCamera(std::string_view id, std::string_view settings);\n> \n> static const std::string &version() { return version_; }\n> \n> diff --git a/include/libcamera/internal/camera_manager.h b/include/libcamera/internal/camera_manager.h\n> index 755928ce..4dbc1dc8 100644\n> --- a/include/libcamera/internal/camera_manager.h\n> +++ b/include/libcamera/internal/camera_manager.h\n> @@ -55,6 +55,9 @@ private:\n> void pipelineFactoryMatch(const PipelineHandlerFactoryBase *factory);\n> void cleanup() LIBCAMERA_TSA_EXCLUDES(mutex_);\n> \n> + std::shared_ptr getMemoryCamera(const PipelineHandlerFactoryBase *factory,\n> + std::string_view settings);\n> +\n> /*\n> * This mutex protects\n> *\n> @@ -70,6 +73,8 @@ private:\n> \n> std::unique_ptr enumerator_;\n> \n> + std::vector memoryCameras_;\n> +\n> std::unique_ptr ipaManager_;\n> \n> const GlobalConfiguration configuration_;\n> diff --git a/include/libcamera/internal/pipeline_handler.h b/include/libcamera/internal/pipeline_handler.h\n> index b4f97477..cb631529 100644\n> --- a/include/libcamera/internal/pipeline_handler.h\n> +++ b/include/libcamera/internal/pipeline_handler.h\n> @@ -70,6 +70,14 @@ public:\n> \n> CameraManager *cameraManager() const { return manager_; }\n> \n> + virtual bool supportsMemoryCamera() { return false; }\n> +\n> + virtual std::shared_ptr createMemoryCamera([[maybe_unused]] DeviceEnumerator *enumerator,\n> + [[maybe_unused]] std::string_view settings)\n> + {\n> + return nullptr;\n> + }\n> +\n> protected:\n> void registerCamera(std::shared_ptr camera);\n> void hotplugMediaDevice(std::shared_ptr media);\n> diff --git a/src/libcamera/camera_manager.cpp b/src/libcamera/camera_manager.cpp\n> index 83510e06..734f5836 100644\n> --- a/src/libcamera/camera_manager.cpp\n> +++ b/src/libcamera/camera_manager.cpp\n> @@ -155,6 +155,13 @@ void CameraManager::Private::pipelineFactoryMatch(const PipelineHandlerFactoryBa\n> {\n> CameraManager *const o = LIBCAMERA_O_PTR();\n> \n> + /* First check for any memory-to-memory camera pipelines. */\n> + {\n> + std::shared_ptr pipe = factory->create(o);\n> + if (pipe->supportsMemoryCamera())\n\nAh, cool, the default is false! Looks good to me :-)\n\nReviewed-by: Isaac Scott \n\n> + memoryCameras_.push_back(std::string(pipe->name()));\n> + }\n> +\n> /* Provide as many matching pipelines as possible. */\n> while (1) {\n> std::shared_ptr pipe = factory->create(o);\n> @@ -167,6 +174,19 @@ void CameraManager::Private::pipelineFactoryMatch(const PipelineHandlerFactoryBa\n> }\n> }\n> \n> +std::shared_ptr CameraManager::Private::getMemoryCamera(const PipelineHandlerFactoryBase *factory,\n> + std::string_view settings)\n> +{\n> + CameraManager *const o = LIBCAMERA_O_PTR();\n> +\n> + std::shared_ptr pipe = factory->create(o);\n> +\n> + pipe->moveToThread(this);\n> +\n> + return pipe->invokeMethod(&PipelineHandler::createMemoryCamera,\n> + ConnectionTypeBlocking, enumerator_.get(), settings);\n> +}\n> +\n> void CameraManager::Private::cleanup()\n> {\n> enumerator_->devicesAdded.disconnect(this);\n> @@ -371,6 +391,9 @@ void CameraManager::stop()\n> * Before calling this function the caller is responsible for ensuring that\n> * the camera manager is running.\n> *\n> + * This function does not list any memory cameras (for processing raw images\n> + * held in memory buffers) that may be available.\n> + *\n> * \\context This function is \\threadsafe.\n> *\n> * \\return List of all available cameras\n> @@ -409,6 +432,47 @@ std::shared_ptr CameraManager::get(std::string_view id)\n> return nullptr;\n> }\n> \n> +/**\n> + * \\brief List the pipeline handlers that support memory cameras\n> + *\n> + * Lists the pipeline handlers in the system that have indicated they\n> + * support memory cameras. Memory cameras are used for processing raw\n> + * camera images stored in memory buffers, where no corresponding\n> + * camera is available.\n> + *\n> + * \\return Vector of pipeline handler ids (strings)\n> + */\n> +std::vector CameraManager::memoryCameras() const\n> +{\n> + return _d()->memoryCameras_;\n> +}\n> +\n> +/**\n> + * \\brief Get a memory camera from the named pipeline handler\n> + * \\param[in] id ID of the pipeline handler that should create the memory camera\n> + *\n> + * This function causes the named pipeline handler to create and return a\n> + * memory camera to the application. Pipeline handlers may support multiple\n> + * simultaneous memory cameras, or none at all.\n> + *\n> + * \\return Shared pointer to Camera object or nullptr if no memory camera\n> + * could be provided\n> + */\n> +std::shared_ptr CameraManager::getMemoryCamera(std::string_view id,\n> + std::string_view settings)\n> +{\n> + for (const auto &name : _d()->memoryCameras_) {\n> + if (name == id) {\n> + const PipelineHandlerFactoryBase *factory;\n> + factory = PipelineHandlerFactoryBase::getFactoryByName(name);\n> +\n> + return _d()->getMemoryCamera(factory, settings);\n> + }\n> + }\n> +\n> + return nullptr;\n> +}\n> +\n> /**\n> * \\var CameraManager::cameraAdded\n> * \\brief Notify of a new camera added to the system\n> diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp\n> index 5c469e5b..c0f3c84e 100644\n> --- a/src/libcamera/pipeline_handler.cpp\n> +++ b/src/libcamera/pipeline_handler.cpp\n> @@ -835,6 +835,29 @@ void PipelineHandler::disconnect()\n> * \\return The CameraManager for this pipeline handler\n> */\n> \n> +/**\n> + * \\fn PipelineHandler::supportsMemoryCamera()\n> + * \\brief Indicate whether this pipeline handler supports memory cameras.\n> + * \\return True if the pipeline handler supports memory cameras, otherwise false.\n> + */\n> +\n> +/**\n> + * \\fn PipelineHandler::createMemoryCamera()\n> + * \\brief Create a memory camera to process raw camera images from a memory buffer\n> + * \\param[in] enumerator The enumerator providing all media devices found in the\n> + * system\n> + * \\param[in] settings A string of settings that the pipeline handler should use\n> + *\n> + * The pipeline handler should create a memory camera, which an application can\n> + * use to process raw camera images that are stored in memory buffers (rather\n> + * than being delivered from a live camera).\n> + *\n> + * The settings should indicate exactly what processing the application requires\n> + * to be performed on the raw image.\n> + *\n> + * \\return Shared pointer to a camera, or a nullptr if none could be created\n> + */\n> +\n> /**\n> * \\class PipelineHandlerFactoryBase\n> * \\brief Base class for pipeline handler factories\n> -- \n> 2.47.3\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 643EDBDCBF\n\tfor ;\n\tTue, 6 Jan 2026 15:56:00 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id A162461FA0;\n\tTue, 6 Jan 2026 16:55:59 +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 5FC5161F9F\n\tfor ;\n\tTue, 6 Jan 2026 16:55:58 +0100 (CET)","from thinkpad.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 F0D8F78E;\n\tTue, 6 Jan 2026 16:55:36 +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=\"jLvsfHn0\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1767714937;\n\tbh=vk2ze0L3hCa6CaFU+g4rNrY6eIprxZTV64lYQaymW1M=;\n\th=In-Reply-To:References:Subject:From:Cc:To:Date:From;\n\tb=jLvsfHn04JqS4vljLM6shdG5VPiVtTqRy4owYGqb8PVbGYmCqAcbl+Ko5yrnhA1A6\n\tDv2opm3VJJVG0w3hZnDV3Q9GDs45EHj9dM7tzP7uLO5owPFOiZi6Sxg17TlvPyfnl3\n\tv8G+wsvyd9qFLdqeQcFWIdBUJHgKB5rK0OobjjXk=","Content-Type":"text/plain; charset=\"utf-8\"","MIME-Version":"1.0","Content-Transfer-Encoding":"quoted-printable","In-Reply-To":"<20251210164055.17856-2-david.plowman@raspberrypi.com>","References":"<20251210164055.17856-1-david.plowman@raspberrypi.com>\n\t<20251210164055.17856-2-david.plowman@raspberrypi.com>","Subject":"Re: [PATCH 01/11] libcamera: Infrastructure to ask for \"memory\"\n\tcameras","From":"Isaac Scott ","Cc":"David Plowman ","To":"David Plowman ,\n\tlibcamera-devel@lists.libcamera.org","Date":"Tue, 06 Jan 2026 15:55:55 +0000","Message-ID":"<176771495548.112111.12971944340047876740@isaac-ThinkPad-T16-Gen-2>","User-Agent":"alot/0.10","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\" "}}]