av/cmd/rv/probe.go

//go:build !nocv
// +build !nocv

/*
DESCRIPTION
  Provides the methods for the turbidity probe using GoCV. Turbidity probe
  will collect the most recent frames in a buffer and write the latest sharpness
  and contrast scores to the probe.

AUTHORS
  Russell Stanley <russell@ausocean.org>

LICENSE
  Copyright (C) 2021-2022 the Australian Ocean Lab (AusOcean)

  It is free software: you can redistribute it and/or modify them
  under the terms of the GNU General Public License as published by the
  Free Software Foundation, either version 3 of the License, or (at your
  option) any later version.

  It is distributed in the hope that it will be useful, but WITHOUT
  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
  for more details.

  You should have received a copy of the GNU General Public License
  in gpl.txt.  If not, see http://www.gnu.org/licenses.
*/

package main

import (
	"os"
	"time"

	"bitbucket.org/ausocean/av/turbidity"
	"bitbucket.org/ausocean/utils/logger"
	"gocv.io/x/gocv"
	"gonum.org/v1/gonum/stat"
)

// Turbidity sensor constants.
const (
	k1, k2     = 8, 8 // Block size, must be divisible by the size template with no remainder.
	filterSize = 3    // Sobel filter size.
	scale      = 1.0  // Amount of scale applied to sobel filter values.
	alpha      = 1.0  // Paramater for contrast equation.
)

// Misc constants.
const (
	maxImages = 10 // Max number of images read when evaluating turbidity.
)

type turbidityProbe struct {
	sharpness, contrast float64
	delay               time.Duration
	ticker              time.Ticker
	ts                  *turbidity.TurbiditySensor
	log                 logger.Logger
}

// NewTurbidityProbe returns a new turbidity probe.
func NewTurbidityProbe(log logger.Logger, delay time.Duration) (*turbidityProbe, error) {
	tp := new(turbidityProbe)
	tp.log = log
	tp.delay = delay
	tp.ticker = *time.NewTicker(delay)

	// Create the turbidity sensor.
	standard := gocv.IMRead("../../turbidity/images/template.jpg", gocv.IMReadGrayScale)
	template := gocv.IMRead("../../turbidity/images/template.jpg", gocv.IMReadGrayScale)
	ts, err := turbidity.NewTurbiditySensor(template, standard, k1, k2, filterSize, scale, alpha)
	if err != nil {
		log.Error("failed create turbidity sensor", "error", err.Error())
	}
	tp.ts = ts
	return tp, nil
}

// Write, reads input h264 frames in the form of a byte stream and writes the the sharpness and contrast
// scores of a video to the the turbidity probe.
func (tp *turbidityProbe) Write(p []byte) (int, error) {
	select {
	case <-tp.ticker.C:
		var imgs []gocv.Mat
		img := gocv.NewMat()

		// Write byte array to a temp file.
		file, err := os.CreateTemp("temp", "video*.h264")
		if err != nil {
			tp.log.Error("failed to create temp file", "error", err.Error())
			return 0, err
		}
		defer os.Remove(file.Name())
		n, err := file.Write(p)
		if err != nil {
			tp.log.Error("failed to write to temporary file", "error", err.Error())
			return n, err
		}

		// Read the file and store each frame.
		vc, err := gocv.VideoCaptureFile(file.Name())
		if err != nil {
			tp.log.Error("failed to open video file", "error", err.Error())
			return len(p), err
		}
		for vc.Read(&img) && len(imgs) < maxImages {
			imgs = append(imgs, img.Clone())
		}

		// Process video data to get saturation and contrast scores.
		res, err := tp.ts.Evaluate(imgs)
		if err != nil {
			tp.log.Error("evaluate failed", "errror", err.Error())
			return len(p), err
		}
		tp.contrast = stat.Mean(res.Contrast, nil)
		tp.sharpness = stat.Mean(res.Sharpness, nil)
	default:
	}
	return len(p), nil
}

func (tp *turbidityProbe) Close() error {
	return nil
}