[libcamera-devel] [PATCH 09/11] libcamera: camera_sensor: Add a new class to model a camera sensor
Laurent Pinchart
laurent.pinchart at ideasonboard.com
Tue Apr 16 00:49:42 CEST 2019
Hi Niklas,
On Mon, Apr 15, 2019 at 11:39:29PM +0200, Niklas Söderlund wrote:
> On 2019-04-15 19:56:58 +0300, Laurent Pinchart wrote:
> > The CameraSensor class abstracts camera sensors and provides helper
> > functions to ease interactions with them. It is currently limited to
> > sensors that expose a single subdev, and offer the same frame sizes for
> > all media bus codes, but will be extended to support more complex
> > sensors as the needs arise.
> >
> > Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> > ---
> > src/libcamera/camera_sensor.cpp | 245 ++++++++++++++++++++++++++
> > src/libcamera/include/camera_sensor.h | 56 ++++++
> > src/libcamera/meson.build | 2 +
> > 3 files changed, 303 insertions(+)
> > create mode 100644 src/libcamera/camera_sensor.cpp
> > create mode 100644 src/libcamera/include/camera_sensor.h
> >
> > diff --git a/src/libcamera/camera_sensor.cpp b/src/libcamera/camera_sensor.cpp
> > new file mode 100644
> > index 000000000000..aca9e77fd986
> > --- /dev/null
> > +++ b/src/libcamera/camera_sensor.cpp
> > @@ -0,0 +1,245 @@
> > +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> > +/*
> > + * Copyright (C) 2019, Google Inc.
> > + *
> > + * camera_sensor.cpp - A camera sensor
> > + */
> > +
> > +#include <algorithm>
> > +#include <float.h>
> > +#include <limits.h>
> > +#include <math.h>
> > +
> > +#include "camera_sensor.h"
> > +#include "formats.h"
> > +#include "v4l2_subdevice.h"
> > +
> > +/**
> > + * \file camera_sensor.h
> > + * \brief A camera sensor
> > + */
> > +
> > +namespace libcamera {
> > +
> > +LOG_DEFINE_CATEGORY(CameraSensor);
> > +
> > +/**
> > + * \class CameraSensor
> > + * \brief A camera sensor
> > + *
> > + * The CameraSensor class eases handling of sensors for pipeline handlers by
> > + * hiding the details of the V4L2 subdevice kernel API and caching sensor
> > + * information.
> > + *
> > + * The implementation is currently limited to sensors that expose a single V4L2
> > + * subdevice with a single pad, and support the same frame sizes for all
> > + * supported media bus codes. It will be extended to support more complex
> > + * devices as the needs arise.
> > + */
> > +
> > +/**
> > + * \brief Construct a CameraSensor
> > + * \param[in] entity The media entity for the camera sensor
> > + *
> > + * Once constructed the instance must be initialized with init().
> > + */
> > +CameraSensor::CameraSensor(const MediaEntity *entity)
> > + : entity_(entity)
> > +{
> > + subdev_ = new V4L2Subdevice(entity);
> > +}
> > +
> > +/**
> > + * \brief Destroy a CameraSensor
> > + */
> > +CameraSensor::~CameraSensor()
> > +{
> > + delete subdev_;
> > +}
> > +
> > +/**
> > + * \brief Initialize the camera sensor instance
> > + *
> > + * This methods perform the initialisation steps of the CameraSensor that may
> > + * fail. It shall be called once and only once after constructing the instance.
> > + *
> > + * \return 0 on success or a negative error code otherwise
> > + */
> > +int CameraSensor::init()
> > +{
> > + int ret;
> > +
> > + if (entity_->pads().size() != 1) {
> > + LOG(CameraSensor, Error)
> > + << "Sensors with more than one pad are not supported"
> > + << std::endl;
> > + return -EINVAL;
> > + }
> > +
> > + ret = subdev_->open();
> > + if (ret < 0)
> > + return ret;
> > +
> > + /* Enumerate and cache media bus codes and sizes. */
> > + const FormatEnum formats = subdev_->formats(0);
> > + if (formats.empty()) {
> > + LOG(CameraSensor, Error)
> > + << "No image format found" << std::endl;
> > + return -EINVAL;
> > + }
> > +
> > + std::transform(formats.begin(), formats.end(),
> > + std::back_inserter(mbusCodes_),
> > + [](decltype(*formats.begin()) f) { return f.first; });
> > +
> > + const std::vector<SizeRange> &sizes = formats.begin()->second;
>
> I might add a comment somewhere around here mentioning the limitation
> and why only sizes from formats.begin() are considered. I had to reread
> the commit message to figure it out. Not a big issue as it's documented
> elsewhere so it won't be forgotten. Maybe me pointing it out here for
> other reviewers benefit is enough.
I'll add the following comment:
/*
* Extract the supported sizes from the first format as we only support
* sensors that offer the same frame sizes for all media bus codes.
* Verify this assumption and reject the sensor if it isn't true.
*/
> > + std::transform(sizes.begin(), sizes.end(), std::back_inserter(sizes_),
> > + [](const SizeRange &range) { return range.max; });
> > +
> > + /*
> > + * Verify the assumption that all available media bus codes support the
> > + * same frame sizes.
> > + */
And will remove this one.
> > + for (auto it = ++formats.begin(); it != formats.end(); ++it) {
> > + if (it->second != sizes) {
> > + LOG(CameraSensor, Error)
> > + << "Frame sizes differ between media bus codes"
> > + << std::endl;
> > + return -EINVAL;
> > + }
> > + }
> > +
> > + /* Sort the sizes. */
> > + std::sort(sizes_.begin(), sizes_.end());
> > +
> > + return 0;
> > +}
> > +
> > +/**
> > + * \fn CameraSensor::entity()
> > + * \brief Retrieve the sensor media entity
> > + * \return The sensor media entity
> > + */
> > +
> > +/**
> > + * \fn CameraSensor::mbusCodes()
> > + * \brief Retrieve the media bus codes supported by the camera sensor
> > + * \return The supported media bus codes
> > + */
> > +
> > +/**
> > + * \fn CameraSensor::sizes()
> > + * \brief Retrieve the frame sizes supported by the camera sensor
> > + * \return The supported frame sizes
> > + */
> > +
> > +/**
> > + * \fn CameraSensor::resolution()
> > + * \brief Retrieve the camera sensor resolution
> > + * \return The camera sensor resolution in pixels
> > + */
>
> Maybe move the function implementation here adding a comment that the
> sizes_ vector is sorted so that the resolution will always be the
> largest one supported.
Done.
> With or without the above nit-pick comments addressed,
>
> Reviewed-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>
>
> > +
> > +/**
> > + * \brief Retrieve the best sensor format for a desired output
> > + * \param[in] mbusCodes The list of acceptable media bus codes
> > + * \param[in] size The desired size
> > + *
> > + * Media bus codes are selected from \a mbusCodes, which lists all acceptable
> > + * codes in decreasing order of preference. This method selects the first code
> > + * from the list that is supported by the sensor. If none of the desired codes
> > + * is supported, it returns an error.
> > + *
> > + * \a size indicates the desired size at the output of the sensor. This method
> > + * selects the best size supported by the sensor according to the following
> > + * criteria.
> > + *
> > + * - The desired \a size shall fit in the sensor output size to avoid the need
> > + * to up-scale.
> > + * - The sensor output size shall match the desired aspect ratio to avoid the
> > + * need to crop the field of view.
> > + * - The sensor output size shall be as small as possible to lower the required
> > + * bandwidth.
> > + *
> > + * The use of this method is optional, as the above criteria may not match the
> > + * needs of all pipeline handlers. Pipeline handlers may implement custom
> > + * sensor format selection when needed.
> > + *
> > + * The returned sensor output format is guaranteed to be acceptable by the
> > + * setFormat() method without any modification.
> > + *
> > + * \return The best sensor output format matching the desired media bus codes
> > + * and size on success, or an empty format otherwise.
> > + */
> > +V4L2SubdeviceFormat CameraSensor::getFormat(const std::vector<unsigned int> &mbusCodes,
> > + const Size &size) const
> > +{
> > + V4L2SubdeviceFormat format{};
> > +
> > + for (unsigned int code : mbusCodes_) {
> > + if (std::any_of(mbusCodes.begin(), mbusCodes.end(),
> > + [code](unsigned int c) { return c == code; })) {
> > + format.mbus_code = code;
> > + break;
> > + }
> > + }
> > +
> > + if (!format.mbus_code) {
> > + LOG(CameraSensor, Debug)
> > + << "No supported format found" << std::endl;
> > + return format;
> > + }
> > +
> > + unsigned int desiredArea = size.width * size.height;
> > + unsigned int bestArea = UINT_MAX;
> > + float desiredRatio = static_cast<float>(size.width) / size.height;
> > + float bestRatio = FLT_MAX;
> > + const Size *bestSize = nullptr;
> > +
> > + for (const Size &sz : sizes_) {
> > + if (sz.width < size.width || sz.height < size.height)
> > + continue;
> > +
> > + float ratio = static_cast<float>(sz.width) / sz.height;
> > + float ratioDiff = fabsf(ratio - desiredRatio);
> > + unsigned int area = sz.width * sz.height;
> > + unsigned int areaDiff = area - desiredArea;
> > +
> > + if (ratioDiff > bestRatio)
> > + continue;
> > +
> > + if (ratioDiff < bestRatio || areaDiff < bestArea) {
> > + bestRatio = ratioDiff;
> > + bestArea = areaDiff;
> > + bestSize = &sz;
> > + }
> > + }
> > +
> > + if (!bestSize) {
> > + LOG(CameraSensor, Debug)
> > + << "No supported size found" << std::endl;
> > + return format;
> > + }
> > +
> > + format.width = bestSize->width;
> > + format.height = bestSize->height;
> > +
> > + return format;
> > +}
> > +
> > +/**
> > + * \brief Set the sensor output format
> > + * \param[in] format The desired sensor output format
> > + *
> > + * \return 0 on success or a negative error code otherwise
> > + */
> > +int CameraSensor::setFormat(V4L2SubdeviceFormat *format)
> > +{
> > + return subdev_->setFormat(0, format);
> > +}
> > +
> > +std::string CameraSensor::logPrefix() const
> > +{
> > + return "'" + subdev_->entity()->name() + "'";
> > +}
> > +
> > +} /* namespace libcamera */
> > diff --git a/src/libcamera/include/camera_sensor.h b/src/libcamera/include/camera_sensor.h
> > new file mode 100644
> > index 000000000000..7d92af05248c
> > --- /dev/null
> > +++ b/src/libcamera/include/camera_sensor.h
> > @@ -0,0 +1,56 @@
> > +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> > +/*
> > + * Copyright (C) 2019, Google Inc.
> > + *
> > + * camera_sensor.h - A camera sensor
> > + */
> > +#ifndef __LIBCAMERA_CAMERA_SENSOR_H__
> > +#define __LIBCAMERA_CAMERA_SENSOR_H__
> > +
> > +#include <string>
> > +#include <vector>
> > +
> > +#include <libcamera/geometry.h>
> > +
> > +#include "log.h"
> > +#include "v4l2_subdevice.h"
> > +
> > +namespace libcamera {
> > +
> > +class MediaEntity;
> > +class V4L2SubdeviceFormat;
> > +
> > +class CameraSensor : public Loggable
> > +{
> > +public:
> > + explicit CameraSensor(const MediaEntity *entity);
> > + ~CameraSensor();
> > +
> > + CameraSensor(const CameraSensor &) = delete;
> > + CameraSensor &operator=(const CameraSensor &) = delete;
> > +
> > + int init();
> > +
> > + const MediaEntity *entity() const { return entity_; }
> > + const std::vector<unsigned int> &mbusCodes() const { return mbusCodes_; }
> > + const std::vector<Size> &sizes() const { return sizes_; }
> > + const Size &resolution() const { return sizes_.back(); }
> > +
> > + V4L2SubdeviceFormat getFormat(const std::vector<unsigned int> &mbusCodes,
> > + const Size &size) const;
> > + int setFormat(V4L2SubdeviceFormat *format);
> > +
> > +protected:
> > + std::string logPrefix() const;
> > +
> > +private:
> > + const MediaEntity *entity_;
> > + V4L2Subdevice *subdev_;
> > +
> > + std::vector<unsigned int> mbusCodes_;
> > + std::vector<Size> sizes_;
> > +};
> > +
> > +} /* namespace libcamera */
> > +
> > +#endif /* __LIBCAMERA_CAMERA_SENSOR_H__ */
> > diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build
> > index cd36ac307518..cf4edec05755 100644
> > --- a/src/libcamera/meson.build
> > +++ b/src/libcamera/meson.build
> > @@ -2,6 +2,7 @@ libcamera_sources = files([
> > 'buffer.cpp',
> > 'camera.cpp',
> > 'camera_manager.cpp',
> > + 'camera_sensor.cpp',
> > 'device_enumerator.cpp',
> > 'event_dispatcher.cpp',
> > 'event_dispatcher_poll.cpp',
> > @@ -23,6 +24,7 @@ libcamera_sources = files([
> > ])
> >
> > libcamera_headers = files([
> > + 'include/camera_sensor.h',
> > 'include/device_enumerator.h',
> > 'include/event_dispatcher_poll.h',
> > 'include/formats.h',
--
Regards,
Laurent Pinchart
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