libcamera/vivid.git - libcamera pipeline handler for VIVID

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/* SPDX-License-Identifier: LGPL-2.1-or-later */ /* * Copyright (C) 2019, Google Inc. * * stream.cpp - Video stream for a Camera */ #include <libcamera/stream.h> #include <iomanip> #include <sstream> /** * \file stream.h * \brief Video stream for a Camera * * A camera device can provide frames in different resolutions and formats * concurrently from a single image source. The Stream class represents * one of the multiple concurrent streams. * * All streams exposed by a camera device share the same image source and are * thus not fully independent. Parameters related to the image source, such as * the exposure time or flash control, are common to all streams. Other * parameters, such as format or resolution, may be specified per-stream, * depending on the capabilities of the camera device. * * Camera devices expose at least one stream, and may expose additional streams * based on the device capabilities. This can be used, for instance, to * implement concurrent viewfinder and video capture, or concurrent viewfinder, * video capture and still image capture. */ namespace libcamera { /** * \struct StreamConfiguration * \brief Configuration parameters for a stream * * The StreamConfiguration structure models all information which can be * configured for a single video stream. */ /** * \var StreamConfiguration::size * \brief Stream size in pixels */ /** * \var StreamConfiguration::pixelFormat * \brief Stream pixel format * * This is a little endian four character code representation of the pixel * format described in V4L2 using the V4L2_PIX_FMT_* definitions. */ /** * \var StreamConfiguration::bufferCount * \brief Requested number of buffers to allocate for the stream */ /** * \brief Assemble and return a string describing the configuration * * \return A string describing the StreamConfiguration */ std::string StreamConfiguration::toString() const { std::stringstream ss; ss.fill(0); ss << size.toString() << "-0x" << std::hex << std::setw(8) << pixelFormat; return ss.str(); } /** * \class StreamUsage * \brief Stream usage information * * The StreamUsage class describes how an application intends to use a stream. * Usages are specified by applications and passed to cameras, that then select * the most appropriate streams and their default configurations. */ /** * \enum StreamUsage::Role * \brief Identify the role a stream is intended to play * \var StreamUsage::StillCapture * The stream is intended to capture high-resolution, high-quality still images * with low frame rate. The captured frames may be exposed with flash. * \var StreamUsage::VideoRecording * The stream is intended to capture video for the purpose of recording or * streaming. The video stream may produce a high frame rate and may be * enhanced with video stabilization. * \var StreamUsage::Viewfinder * The stream is intended to capture video for the purpose of display on the * local screen. The StreamUsage includes the desired resolution. Trade-offs * between quality and usage of system resources are acceptable. */ /** * \fn StreamUsage::role() * \brief Retrieve the stream role * \return The stream role */ /** * \fn StreamUsage::size() * \brief Retrieve desired size * \return The desired size */ /** * \brief Create a stream usage * \param[in] role Stream role */ StreamUsage::StreamUsage(Role role) : role_(role) { } /** * \brief Create a stream usage with a desired size * \param[in] role Stream role * \param[in] size The desired size */ StreamUsage::StreamUsage(Role role, const Size &size) : role_(role), size_(size) { } /** * \class Stream * \brief Video stream for a camera * * The Stream class models all static information which are associated with a * single video stream. Streams are exposed by the Camera object they belong to. * * Cameras may supply more than one stream from the same video source. In such * cases an application can inspect all available streams and select the ones * that best fit its use case. * * \todo Add capabilities to the stream API. Without this the Stream class only * serves to reveal how many streams of unknown capabilities a camera supports. * This in itself is productive as it allows applications to configure and * capture from one or more streams even if they won't be able to select the * optimal stream for the task. */ /** * \class Stream::StillCapture * \brief Describe a still capture usage */ Stream::StillCapture::StillCapture() : StreamUsage(Role::StillCapture) { } /** * \class Stream::VideoRecording * \brief Describe a video recording usage */ Stream::VideoRecording::VideoRecording() : StreamUsage(Role::VideoRecording) { } /** * \class Stream::Viewfinder * \brief Describe a viewfinder usage */ /** * \brief Create a viewfinder usage with a desired dimension * \param[in] width The desired viewfinder width


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