[libcamera-devel] [RFC PATCH v1] libcamera: isp: Add ISP class

[paul.elder at ideasonboard.com]

Hi Siyuan,

Thank you for the patch.

On Wed, Sep 01, 2021 at 02:59:08PM +0100, Siyuan Fan wrote:
> From: Fan Siyuan <siyuan.fan at foxmail.com>
> 
> The ISP class is a abstract base class of software ISP. It includes image
> format configuration, ISP algorithm parameters parser, pixel processing
> image export and thread configuration.
> 
> This new class will be used as the basic class for ISPCPU and ISPGPU.
> 
> Signed-off-by: Fan Siyuan <siyuan.fan at foxmail.com>
> ---
> 
> ISP Parameters Tuning is a important part, so I've designed a parameters
> parser in order that users can call any algorithm combination by passing
> any number of tuple. Each tuple format is including algorithm name string
> and algorithm param, such as tuple<string, int> for black level correct. 
> Currently this function is only a demo. I'm thus sending it as an RFC.

I don't quite see how you imagine parse() to be used. Do you "configure"
the function that you want to run the ISP with first, and then tell it
to process it? What's wrong with passing the list of command-parameter
pairs into the processing function directly?

I think that the processing function should also return statistics. For
a CPU ISP it's not unreasonable for the control and processing to be
together, but remember that this interface must be usable for a GPU ISP
as well, which would have separate control and processing.


Paul

> ---
>  include/libcamera/internal/isp.h | 67 ++++++++++++++++++++++++++++++++
>  1 file changed, 67 insertions(+)
>  create mode 100644 include/libcamera/internal/isp.h
> 
> diff --git a/include/libcamera/internal/isp.h b/include/libcamera/internal/isp.h
> new file mode 100644
> index 00000000..caab7050
> --- /dev/null
> +++ b/include/libcamera/internal/isp.h
> @@ -0,0 +1,67 @@
> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> +/*
> + * Copyright (C) 2021, Siyuan Fan <siyuan.fan at foxmail.com>
> + *
> + * isp.h - The software ISP abstract base class
> + */
> +#ifndef __LIBCAMERA_INTERNAL_ISP_H__
> +#define __LIBCAMERA_INTERNAL_ISP_H__
> +
> +#include <vector>
> +#include <memory>
> +#include <tuple>
> +
> +#include <libcamera/formats.h>
> +#include <libcamera/framebuffer.h>
> +#include <libcamera/geometry.h>
> +#include <libcamera/pixel_format.h>
> +
> +#include "libcamera/base/object.h"
> +#include "libcamera/base/signal.h"
> +
> +namespace libcamera{
> +
> +class ISP : public Object
> +{
> +public:
> +        ISP() {}
> +
> +        virtual ~ISP() {}
> +
> +        template<class F, class...Ts, std::size_t...Is>
> +        void for_each_in_tuple(const std::tuple<Ts...> & tuple, F func, std::index_sequence<Is...>) {
> +   
> +                return (void(func(std::get<Is>(tuple))), ...);
> +        }
> +
> +        template<class F, class...Ts>
> +        void for_each_in_tuple(const std::tuple<Ts...> & tuple, F func) {
> +                for_each_in_tuple(tuple, func, std::make_index_sequence<sizeof...(Ts)>());
> +        }
> +
> +        template<typename T, typename... Args>
> +        void parse(const T &head, const Args &... rest)
> +        {
> +                for_each_in_tuple(head, [&](const auto &x) {
> +                        // parse parameters for diff algorithm
> +                });
> +        }
> +
> +        virtual int configure(PixelFormat inputFormat, PixelFormat outputFormat, Size inputSize, Size outputSize) = 0;
> +
> +        virtual void processing(FrameBuffer *srcBuffer, FrameBuffer *dstBuffer,
> +                                int width, int height) = 0;
> +
> +        virtual int exportBuffers(std::vector<std::unique_ptr<FrameBuffer>> *buffers,
> +                                  unsigned int count, int width, int height) = 0;
> +
> +        virtual void start() = 0;
> +
> +        virtual void stop() = 0;
> +
> +        Signal<FrameBuffer *, FrameBuffer *> ispCompleted;
> +};
> +
> +} /* namespace libcamera */
> +
> +#endif /* __LIBCAMERA_INTERNAL_ISP_H__ */
> -- 
> 2.20.1
>