[libcamera-devel] [PATCH v3 1/4] libcamera: Introduce camera sensor database

[Jacopo Mondi]

Hi Niklas,

On Tue, Dec 29, 2020 at 06:20:40PM +0100, Niklas Söderlund wrote:
> Hi Jacopo,
>
> Thanks for your work.
>
> On 2020-12-28 17:52:00 +0100, Jacopo Mondi wrote:
> > Introduce a 'database' of camera sensor information, which contains
> > a the camera sensor properties which is not possible, or desirable,
> > to retrieve at run-time.
> >
> > The camera sensor database is accessed through the static SensorDatabase
> > class which provides a single method to obtain the sensor information.
> >
> > Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
> > ---
> >  include/libcamera/internal/meson.build       |   1 +
> >  include/libcamera/internal/sensor_database.h |  28 +++++
> >  src/libcamera/meson.build                    |   1 +
> >  src/libcamera/sensor_database.cpp            | 102 +++++++++++++++++++
> >  4 files changed, 132 insertions(+)
> >  create mode 100644 include/libcamera/internal/sensor_database.h
> >  create mode 100644 src/libcamera/sensor_database.cpp
> >
> > diff --git a/include/libcamera/internal/meson.build b/include/libcamera/internal/meson.build
> > index 1b1bdc779512..e1f22f238a10 100644
> > --- a/include/libcamera/internal/meson.build
> > +++ b/include/libcamera/internal/meson.build
> > @@ -38,6 +38,7 @@ libcamera_internal_headers = files([
> >      'process.h',
> >      'pub_key.h',
> >      'semaphore.h',
> > +    'sensor_database.h',
> >      'sysfs.h',
> >      'thread.h',
> >      'timer.h',
> > diff --git a/include/libcamera/internal/sensor_database.h b/include/libcamera/internal/sensor_database.h
> > new file mode 100644
> > index 000000000000..e074b3029932
> > --- /dev/null
> > +++ b/include/libcamera/internal/sensor_database.h
> > @@ -0,0 +1,28 @@
> > +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> > +/*
> > + * Copyright (C) 2020, Google Inc.
> > + *
> > + * sensor_database.h - Database of camera sensor properties
> > + */
> > +#ifndef __LIBCAMERA_SENSOR_DATABASE_H__
> > +#define __LIBCAMERA_SENSOR_DATABASE_H__
> > +
> > +#include <string>
> > +
> > +#include <libcamera/geometry.h>
> > +
> > +namespace libcamera {
> > +
> > +struct SensorInfo {
> > +	Size unitCellSize;
> > +};
> > +
> > +class SensorDatabase
> > +{
> > +public:
> > +	static const SensorInfo *get(const std::string &sensor);
> > +};
> > +
> > +} /* namespace libcamera */
> > +
> > +#endif /* __LIBCAMERA_SENSOR_DATABASE_H__ */
> > diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build
> > index 387d5d88ecae..54f3b81ad7b2 100644
> > --- a/src/libcamera/meson.build
> > +++ b/src/libcamera/meson.build
> > @@ -41,6 +41,7 @@ libcamera_sources = files([
> >      'pub_key.cpp',
> >      'request.cpp',
> >      'semaphore.cpp',
> > +    'sensor_database.cpp',
> >      'signal.cpp',
> >      'stream.cpp',
> >      'sysfs.cpp',
> > diff --git a/src/libcamera/sensor_database.cpp b/src/libcamera/sensor_database.cpp
> > new file mode 100644
> > index 000000000000..5f8538a62388
> > --- /dev/null
> > +++ b/src/libcamera/sensor_database.cpp
> > @@ -0,0 +1,102 @@
> > +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> > +/*
> > + * Copyright (C) 2020, Google Inc.
> > + *
> > + * sensor_database.cpp - Database of camera sensor properties
> > + */
> > +
> > +#include "libcamera/internal/sensor_database.h"
> > +
> > +#include <algorithm>
> > +
> > +namespace libcamera {
> > +
> > +/**
> > + * \file sensor_database.h
> > + * \brief Database of camera sensor properties
> > + *
> > + * The camera sensor database collects information on camera sensors
> > + * which is not possible or desirable to retrieve at run-time.
> > + */
> > +
> > +/**
> > + * \class SensorDatabase
> > + * \brief Access the database of camera sensor properties
> > + *
> > + * The database is indexed using the camera sensor model, as reported by the
> > + * properties::Model property, and for each supported sensor it contains a
> > + * SensorInfo list of properties.
> > + *
> > + * The class provides a single static getInfo() method to access the sensor
> > + * database entries. If the sensor is not supported in the database nullptr is
> > + * returned.
> > + */
> > +
> > +/**
> > + * \struct SensorInfo
> > + * \brief List of sensor properties
> > + *
> > + * \var SensorInfo::unitCellSize
> > + * \brief The physical size of pixel, including pixel edges. Width x height in
> > + * nano-meters.
> > + */
> > +
> > +namespace {
> > +
> > +/**
> > + * \brief Sony IMX219 sensor properties
> > + */
> > +constexpr SensorInfo imx219Info = {
> > +	.unitCellSize = { 1120, 1120 }
> > +};
> > +
> > +/**
> > + * \brief Omnivision ov5670 sensor properties
> > + */
> > +constexpr SensorInfo ov5670Info = {
> > +	.unitCellSize = { 1120, 1120 }
> > +};
> > +
> > +/**
> > + * \brief Omnivision 13858 sensor properties
> > + */
> > +constexpr SensorInfo ov13858Info = {
> > +	.unitCellSize = { 1120, 1120 }
> > +};
> > +
> > +#define SENSOR_INFO(_sensor) \
> > +	{ #_sensor, &_sensor##Info }
> > +
> > +/*
> > + * \brief The database of sensor properties
> > + */
> > +constexpr std::pair<const char *const, const SensorInfo *> sensorDatabase__[] = {
>
> Maybe something for later but if model registration similar to
> REGISTER_PIPELINE_HANDLER() this could be a std::map which would improve
> lookup speeds, if we ever get a large set of sensors. But I think this
> could be done on-top as it won't impact any users.

My understanding is that the factory implementation we have realized
with REGISTER_PIPELINE_HANDLER() guarantees the static list of
handlers is initialized at library startup, but does not guarantee
that it is compile-time evaluated and statically initialized as
constexpr does.

as detailed in the cover letter I moved from an std::map, to an
std::array, and finally fell back on a plain C-style array to be able
to ensure that and please all the compilers I've tested with.

Thanks
  j


>
> Reviewed-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>
>
> > +	SENSOR_INFO(imx219),
> > +	SENSOR_INFO(ov5670),
> > +	SENSOR_INFO(ov13858),
> > +};
> > +
> > +const SensorInfo *getInfo(const std::string &sensor)
> > +{
> > +	for (unsigned int i = 0; i < std::size(sensorDatabase__); ++i) {
> > +		if (sensorDatabase__[i].first == sensor)
> > +			return sensorDatabase__[i].second;
> > +	}
> > +
> > +	return nullptr;
> > +}
> > +
> > +} /* namespace */
> > +
> > +/**
> > + * \brief Retrieve the properties associated with a sensor
> > + * \param sensor The sensor model name
> > + * \return A pointer to the SensorInfo instance associated with a sensor or
> > + * nullptr if the sensor is not supported in the database
> > + */
> > +const SensorInfo *SensorDatabase::get(const std::string &sensor)
> > +{
> > +	return getInfo(sensor);
> > +}
> > +
> > +} /* namespace libcamera */
> > --
> > 2.29.2
> >
> > _______________________________________________
> > libcamera-devel mailing list
> > libcamera-devel at lists.libcamera.org
> > https://lists.libcamera.org/listinfo/libcamera-devel
>
> --
> Regards,
> Niklas Söderlund