av/revid/revid.go

/*
NAME
  revid.go

AUTHORS
  Saxon A. Nelson-Milton <saxon@ausocean.org>
  Alan Noble <alan@ausocean.org>
  Dan Kortschak <dan@ausocean.org>
  Trek Hopton <trek@ausocean.org>
  Scott Barnard <scott@ausocean.org>

LICENSE
  revid is Copyright (C) 2017-2020 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 revid provides an API for reading, transcoding, and writing audio/video streams and files.
package revid

import (
	"errors"
	"fmt"
	"io"
	"os/exec"
	"strconv"
	"strings"
	"sync"
	"time"

	"bitbucket.org/ausocean/av/codec/codecutil"
	"bitbucket.org/ausocean/av/codec/h264"
	"bitbucket.org/ausocean/av/codec/h265"
	"bitbucket.org/ausocean/av/codec/mjpeg"
	"bitbucket.org/ausocean/av/container/flv"
	"bitbucket.org/ausocean/av/container/mts"
	"bitbucket.org/ausocean/av/device"
	"bitbucket.org/ausocean/av/device/file"
	"bitbucket.org/ausocean/av/device/geovision"
	"bitbucket.org/ausocean/av/device/raspivid"
	"bitbucket.org/ausocean/av/device/webcam"
	"bitbucket.org/ausocean/av/filter"
	"bitbucket.org/ausocean/av/revid/config"
	"bitbucket.org/ausocean/iot/pi/netsender"
	"bitbucket.org/ausocean/utils/bitrate"
	"bitbucket.org/ausocean/utils/ioext"
	"bitbucket.org/ausocean/utils/logger"
	"bitbucket.org/ausocean/utils/vring"
)

// RTMP connection properties.
const (
	rtmpConnectionMaxTries = 5
	rtmpConnectionTimeout  = 10
)

const pkg = "revid: "

type Logger interface {
	SetLevel(int8)
	Log(level int8, message string, params ...interface{})
}

// Revid provides methods to control a revid session; providing methods
// to start, stop and change the state of an instance using the Config struct.
type Revid struct {
	// config holds the Revid configuration.
	// For historical reasons it also handles logging.
	// FIXME(kortschak): The relationship of concerns
	// in config/ns is weird.
	cfg config.Config

	// ns holds the netsender.Sender responsible for HTTP.
	ns *netsender.Sender

	// input will capture audio or video from which we can read data.
	input device.AVDevice

	// closeInput holds the cleanup function return from setupInput and is called
	// in Revid.Stop().
	closeInput func() error

	// cmd is the exec'd process that may be used to produce
	// the input stream.
	// FIXME(kortschak): This should not exist. Replace this
	// with a context.Context cancellation.
	cmd *exec.Cmd

	// lexTo, encoder and packer handle transcoding the input stream.
	lexTo func(dest io.Writer, src io.Reader, delay time.Duration) error

	// filters will hold the filter interface that will write to the chosen filter from the lexer.
	filters []filter.Filter

	// encoders will hold the multiWriteCloser that writes to encoders from the filter.
	encoders io.WriteCloser

	// running is used to keep track of revid's running state between methods.
	running bool

	// mu is used to protect isRunning during concurrent use.
	mu sync.Mutex

	// wg will be used to wait for any processing routines to finish.
	wg sync.WaitGroup

	// err will channel errors from revid routines to the handle errors routine.
	err chan error

	// bitrate is used for bitrate calculations.
	bitrate bitrate.Calculator
}

// New returns a pointer to a new Revid with the desired configuration, and/or
// an error if construction of the new instance was not successful.
func New(c config.Config, ns *netsender.Sender) (*Revid, error) {
	r := Revid{ns: ns, err: make(chan error)}
	err := r.setConfig(c)
	if err != nil {
		return nil, fmt.Errorf("could not set config, failed with error: %w", err)
	}
	r.cfg.Logger.SetLevel(c.LogLevel)
	go r.handleErrors()
	return &r, nil
}

// Config returns a copy of revids current config.
//
// Config is not safe for concurrent use.
func (r *Revid) Config() config.Config {
	return r.cfg
}

// TODO(Saxon): put more thought into error severity and how to handle these.
func (r *Revid) handleErrors() {
	for {
		err := <-r.err
		if err != nil {
			r.cfg.Logger.Log(logger.Error, pkg+"async error", "error", err.Error())
		}
	}
}

// Bitrate returns the result of the  most recent bitrate check.
func (r *Revid) Bitrate() int {
	return r.bitrate.Bitrate()
}

// reset swaps the current config of a Revid with the passed
// configuration; checking validity and returning errors if not valid. It then
// sets up the data pipeline accordingly to this configuration.
func (r *Revid) reset(c config.Config) error {
	err := r.setConfig(c)
	if err != nil {
		return err
	}

	r.cfg.Logger.SetLevel(c.LogLevel)

	err = r.setupPipeline(
		func(dst io.WriteCloser, fps float64) (io.WriteCloser, error) {
			var st int
			var encOptions []func(*mts.Encoder) error

			switch r.cfg.Input {
			case config.InputRaspivid:
				switch r.cfg.InputCodec {
				case codecutil.H264:
					st = mts.EncodeH264
				case codecutil.MJPEG:
					st = mts.EncodeMJPEG
					encOptions = append(encOptions, mts.TimeBasedPSI(time.Duration(r.cfg.PSITime)*time.Second))
					r.cfg.CBR = true
				default:
					panic("unknown input codec for raspivid input")
				}
			case config.InputFile, config.InputV4L:
				switch r.cfg.InputCodec {
				case codecutil.H264:
					st = mts.EncodeH264
				case codecutil.MJPEG:
					st = mts.EncodeMJPEG
					encOptions = append(encOptions, mts.TimeBasedPSI(time.Duration(r.cfg.PSITime)*time.Second))
					r.cfg.CBR = true
				default:
					panic(fmt.Sprintf("unknown input codec %d for v4l or input file input", r.cfg.InputCodec))
				}
			case config.InputRTSP:
				switch r.cfg.InputCodec {
				case codecutil.H265:
					st = mts.EncodeH265
				case codecutil.H264:
					st = mts.EncodeH264
				case codecutil.MJPEG:
					st = mts.EncodeMJPEG
					encOptions = append(encOptions, mts.TimeBasedPSI(time.Duration(r.cfg.PSITime)*time.Second))
					r.cfg.CBR = true
				default:
					panic("unknown input codec for RTSP input")
				}
			case config.InputAudio:
				st = mts.EncodeAudio
			default:
				panic("unknown input type")
			}

			return mts.NewEncoder(dst, float64(fps), st, encOptions...)
		},
		func(dst io.WriteCloser, fps int) (io.WriteCloser, error) {
			return flv.NewEncoder(dst, true, true, fps)
		},
		ioext.MultiWriteCloser,
	)

	if err != nil {
		return err
	}

	return nil
}

// setConfig takes a config, checks it's validity and then replaces the current
// revid config.
func (r *Revid) setConfig(config config.Config) error {
	r.cfg.Logger = config.Logger
	err := config.Validate()
	if err != nil {
		return errors.New("Config struct is bad: " + err.Error())
	}
	r.cfg = config
	return nil
}

// setupPipeline constructs the revid dataPipeline. Inputs, encoders and
// senders are created and linked based on the current revid config.
//
// mtsEnc and flvEnc will be called to obtain an mts encoder and flv encoder
// respectively. multiWriter will be used to create an ioext.multiWriteCloser
// so that encoders can write to multiple senders.
func (r *Revid) setupPipeline(mtsEnc func(dst io.WriteCloser, rate float64) (io.WriteCloser, error), flvEnc func(dst io.WriteCloser, rate int) (io.WriteCloser, error), multiWriter func(...io.WriteCloser) io.WriteCloser) error {
	// encoders will hold the encoders that are required for revid's current
	// configuration.
	var encoders []io.WriteCloser

	// mtsSenders will hold the senders the require MPEGTS encoding, and flvSenders
	// will hold senders that require FLV encoding.
	var mtsSenders, flvSenders []io.WriteCloser

	// We will go through our outputs and create the corresponding senders to add
	// to mtsSenders if the output requires MPEGTS encoding, or flvSenders if the
	// output requires FLV encoding.
	var w io.WriteCloser
	for _, out := range r.cfg.Outputs {
		switch out {
		case config.OutputHTTP:
			rb, err := vring.NewBuffer(r.cfg.RBMaxElements, r.cfg.RBCapacity, time.Duration(r.cfg.RBWriteTimeout)*time.Second)
			if err != nil {
				return fmt.Errorf("could not initialise MTS ring buffer: %w", err)
			}
			w = newMtsSender(
				newHttpSender(r.ns, r.cfg.Logger.Log, r.bitrate.Report),
				r.cfg.Logger.Log,
				rb,
				r.cfg.ClipDuration,
			)
			mtsSenders = append(mtsSenders, w)
		case config.OutputRTP:
			w, err := newRtpSender(r.cfg.RTPAddress, r.cfg.Logger.Log, r.cfg.FrameRate, r.bitrate.Report)
			if err != nil {
				r.cfg.Logger.Log(logger.Warning, pkg+"rtp connect error", "error", err.Error())
			}
			mtsSenders = append(mtsSenders, w)
		case config.OutputFile:
			w, err := newFileSender(r.cfg.OutputPath)
			if err != nil {
				return err
			}
			mtsSenders = append(mtsSenders, w)
		case config.OutputRTMP:
			rb, err := vring.NewBuffer(r.cfg.RBMaxElements, r.cfg.RBCapacity, time.Duration(r.cfg.RBWriteTimeout)*time.Second)
			if err != nil {
				return fmt.Errorf("could not initialise RTMP ring buffer: %w", err)
			}
			w, err := newRtmpSender(
				r.cfg.RTMPURL,
				rtmpConnectionTimeout,
				rtmpConnectionMaxTries,
				rb,
				r.cfg.Logger.Log,
				r.bitrate.Report,
			)
			if err != nil {
				r.cfg.Logger.Log(logger.Warning, pkg+"rtmp connect error", "error", err.Error())
			}
			flvSenders = append(flvSenders, w)
		}
	}

	// If we have some senders that require MPEGTS encoding then add an MPEGTS
	// encoder to revid's encoder slice, and give this encoder the mtsSenders
	// as a destination.
	if len(mtsSenders) != 0 {
		mw := multiWriter(mtsSenders...)
		e, _ := mtsEnc(mw, r.cfg.WriteRate)
		encoders = append(encoders, e)
	}

	// If we have some senders that require FLV encoding then add an FLV
	// encoder to revid's encoder slice, and give this encoder the flvSenders
	// as a destination.
	if len(flvSenders) != 0 {
		mw := multiWriter(flvSenders...)
		e, err := flvEnc(mw, int(r.cfg.FrameRate))
		if err != nil {
			return err
		}
		encoders = append(encoders, e)
	}

	r.encoders = multiWriter(encoders...)

	l := len(r.cfg.Filters)
	r.filters = []filter.Filter{filter.NewNoOp(r.encoders)}
	if l != 0 {
		r.filters = make([]filter.Filter, l)
		dst := r.encoders

		for i := l - 1; i >= 0; i-- {
			switch r.cfg.Filters[i] {
			case config.FilterNoOp:
				r.filters[i] = filter.NewNoOp(dst)
			case config.FilterMOG:
				r.filters[i] = filter.NewMOGFilter(dst, r.cfg.MOGMinArea, r.cfg.MOGThreshold, int(r.cfg.MOGHistory), r.cfg.ShowWindows, r.cfg.MotionInterval)
			case config.FilterVariableFPS:
				r.filters[i] = filter.NewVariableFPSFilter(dst, r.cfg.MinFPS, filter.NewMOGFilter(dst, r.cfg.MOGMinArea, r.cfg.MOGThreshold, int(r.cfg.MOGHistory), r.cfg.ShowWindows, r.cfg.MotionInterval))
			case config.FilterKNN:
				r.filters[i] = filter.NewKNNFilter(dst, r.cfg.KNNMinArea, r.cfg.KNNThreshold, int(r.cfg.KNNHistory), int(r.cfg.KNNKernel), r.cfg.ShowWindows, r.cfg.MotionInterval)
			case config.FilterDifference:
				r.filters[i] = filter.NewDifference(dst, r.cfg.ShowWindows, r.cfg.DiffThreshold)
			default:
				panic("Undefined Filter")
			}
			dst = r.filters[i]
		}

	}

	switch r.cfg.Input {
	case config.InputRaspivid:
		r.input = raspivid.New(r.cfg.Logger)

		switch r.cfg.InputCodec {
		case codecutil.H264:
			r.lexTo = h264.Lex
		case codecutil.MJPEG:
			r.lexTo = mjpeg.Lex
		}

	case config.InputV4L:
		r.input = webcam.New(r.cfg.Logger)
		switch r.cfg.InputCodec {
		case codecutil.H264:
			r.lexTo = h264.Lex
		case codecutil.MJPEG:
			r.lexTo = mjpeg.Lex
		}

	case config.InputFile:
		r.input = file.New()
		switch r.cfg.InputCodec {
		case codecutil.H264:
			r.lexTo = h264.Lex
		case codecutil.MJPEG:
			r.lexTo = mjpeg.Lex
		}

	case config.InputRTSP:
		r.input = geovision.New(r.cfg.Logger)

		switch r.cfg.InputCodec {
		case codecutil.H264:
			r.lexTo = h264.NewExtractor().Extract
		case codecutil.H265:
			r.lexTo = h265.NewLexer(false).Lex
		case codecutil.MJPEG:
			r.lexTo = mjpeg.NewExtractor().Extract
		}

	case config.InputAudio:
		err := r.setupAudio()
		if err != nil {
			return err
		}
	}

	// Configure the input device. We know that defaults are set, so no need to
	// return error, but we should log.
	err := r.input.Set(r.cfg)
	if err != nil {
		r.cfg.Logger.Log(logger.Warning, pkg+"errors from configuring input device", "errors", err)
	}

	return nil
}

// Start invokes a Revid to start processing video from a defined input
// and packetising (if theres packetization) to a defined output.
//
// Start is safe for concurrent use.
func (r *Revid) Start() error {
	if r.IsRunning() {
		r.cfg.Logger.Log(logger.Warning, pkg+"start called, but revid already running")
		return nil
	}

	r.mu.Lock()
	defer r.mu.Unlock()

	r.cfg.Logger.Log(logger.Info, pkg+"starting Revid")
	err := r.reset(r.cfg)
	if err != nil {
		r.Stop()
		return err
	}

	// Calculate delay between frames based on FileFPS.
	d := time.Duration(0)
	if r.cfg.FileFPS != 0 {
		d = time.Duration(1000/r.cfg.FileFPS) * time.Millisecond
	}

	r.wg.Add(1)
	go r.processFrom(r.input, d)

	r.running = true
	return nil
}

// Stop closes down the pipeline. This closes encoders and sender output routines,
// connections, and/or files.
//
// Stop is safe for concurrent use.
func (r *Revid) Stop() {
	if !r.IsRunning() {
		r.cfg.Logger.Log(logger.Warning, pkg+"stop called but revid isn't running")
		return
	}

	r.mu.Lock()
	defer r.mu.Unlock()

	err := r.input.Stop()
	if err != nil {
		r.cfg.Logger.Log(logger.Error, pkg+"could not stop input", "error", err.Error())
	}

	r.cfg.Logger.Log(logger.Info, pkg+"closing pid peline")
	err = r.encoders.Close()
	if err != nil {
		r.cfg.Logger.Log(logger.Error, pkg+"failed to close pipeline", "error", err.Error())
	}

	for _, filter := range r.filters {
		err = filter.Close()
		if err != nil {
			r.cfg.Logger.Log(logger.Error, pkg+"failed to close pipeline", "error", err.Error())
		}
	}

	r.cfg.Logger.Log(logger.Info, pkg+"closed pipeline")

	if r.cmd != nil && r.cmd.Process != nil {
		r.cfg.Logger.Log(logger.Info, pkg+"killing input proccess")
		r.cmd.Process.Kill()
	}
	r.cfg.Logger.Log(logger.Info, pkg+"waiting for routines to close")

	r.wg.Wait()

	r.cfg.Logger.Log(logger.Info, pkg+"revid stopped")
	r.running = false
}

func (r *Revid) IsRunning() bool {
	r.mu.Lock()
	defer r.mu.Unlock()
	return r.running
}

// Update takes a map of variables and their values and edits the current config
// if the variables are recognised as valid parameters.
//
// Update is safe for concurrent use.
func (r *Revid) Update(vars map[string]string) error {
	if r.IsRunning() {
		r.Stop()
	}

	r.mu.Lock()
	defer r.mu.Unlock()
	//look through the vars and update revid where needed
	for key, value := range vars {
		switch key {
		case "Input":
			v, ok := map[string]uint8{"raspivid": config.InputRaspivid, "rtsp": config.InputRTSP, "v4l": config.InputV4L, "file": config.InputFile}[strings.ToLower(value)]
			if !ok {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid input var", "value", value)
				break
			}
			r.cfg.Input = v
		case "Saturation":
			s, err := strconv.Atoi(value)
			if err != nil {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid saturation param", "value", value)
				break
			}
			r.cfg.Saturation = int(s)
		case "Brightness":
			b, err := strconv.Atoi(value)
			if err != nil {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid brightness param", "value", value)
				break
			}
			r.cfg.Brightness = uint(b)
		case "Exposure":
			r.cfg.Exposure = value
		case "AutoWhiteBalance":
			r.cfg.AutoWhiteBalance = value
		case "InputCodec":
			switch value {
			case "H264":
				r.cfg.InputCodec = codecutil.H264
			case "MJPEG":
				r.cfg.InputCodec = codecutil.MJPEG
			default:
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid InputCodec variable value", "value", value)
			}
		case "Outputs":
			outputs := strings.Split(value, ",")
			r.cfg.Outputs = make([]uint8, len(outputs))

			for i, output := range outputs {
				switch output {
				case "File":
					r.cfg.Outputs[i] = config.OutputFile
				case "Http":
					r.cfg.Outputs[i] = config.OutputHTTP
				case "Rtmp":
					r.cfg.Outputs[i] = config.OutputRTMP
				case "Rtp":
					r.cfg.Outputs[i] = config.OutputRTP
				default:
					r.cfg.Logger.Log(logger.Warning, pkg+"invalid outputs param", "value", value)
					continue
				}
			}
		case "Output":
			r.cfg.Outputs = make([]uint8, 1)
			switch strings.ToLower(value) {
			case "file":
				r.cfg.Outputs[0] = config.OutputFile
			case "http":
				r.cfg.Outputs[0] = config.OutputHTTP
			case "rtmp":
				r.cfg.Outputs[0] = config.OutputRTMP
			case "rtp":
				r.cfg.Outputs[0] = config.OutputRTP
			default:
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid output param", "value", value)
				continue
			}

		case "RtmpUrl":
			r.cfg.RTMPURL = value
		case "RtpAddress":
			r.cfg.RTPAddress = value
		case "Bitrate":
			v, err := strconv.Atoi(value)
			if err != nil {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid framerate param", "value", value)
				break
			}
			r.cfg.Bitrate = uint(v)
		case "OutputPath":
			r.cfg.OutputPath = value
		case "InputPath":
			r.cfg.InputPath = value
		case "Height":
			h, err := strconv.Atoi(value)
			if err != nil {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid height param", "value", value)
				break
			}
			r.cfg.Height = uint(h)
		case "Width":
			w, err := strconv.Atoi(value)
			if err != nil {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid width param", "value", value)
				break
			}
			r.cfg.Width = uint(w)
		case "FrameRate":
			v, err := strconv.Atoi(value)
			if err != nil {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid framerate param", "value", value)
				break
			}
			r.cfg.FrameRate = uint(v)
		case "Rotation":
			v, err := strconv.Atoi(value)
			if err != nil || v > 359 {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid rotation param", "value", value)
				break
			}
			r.cfg.Rotation = uint(v)
		case "HttpAddress":
			r.cfg.HTTPAddress = value
		case "Quantization":
			v, err := strconv.Atoi(value)
			if err != nil {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid quantization param", "value", v)
				break
			}
			r.cfg.Quantization = uint(v)
		case "MinFrames":
			v, err := strconv.Atoi(value)
			if err != nil {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid MinFrames param", "value", value)
				break
			}
			r.cfg.MinFrames = uint(v)

		case "ClipDuration":
			v, err := strconv.Atoi(value)
			if err != nil {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid ClipDuration param", "value", value)
				break
			}
			r.cfg.ClipDuration = time.Duration(v) * time.Second

		case "HorizontalFlip":
			switch strings.ToLower(value) {
			case "true":
				r.cfg.HorizontalFlip = true
			case "false":
				r.cfg.HorizontalFlip = false
			default:
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid HorizontalFlip param", "value", value)
			}
		case "VerticalFlip":
			switch strings.ToLower(value) {
			case "true":
				r.cfg.VerticalFlip = true
			case "false":
				r.cfg.VerticalFlip = false
			default:
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid VerticalFlip param", "value", value)
			}
		case "Filters":
			filters := strings.Split(value, ",")
			m := map[string]int{"NoOp": config.FilterNoOp, "MOG": config.FilterMOG, "VariableFPS": config.FilterVariableFPS, "KNN": config.FilterKNN, "Difference": config.FilterDifference}
			r.cfg.Filters = make([]int, len(filters))
			for i, filter := range filters {
				v, ok := m[filter]
				if !ok {
					r.cfg.Logger.Log(logger.Warning, pkg+"invalid Filters param", "value", value)
				}
				r.cfg.Filters[i] = v
			}
		case "MotionInterval":
			v, err := strconv.Atoi(value)
			if err != nil || v < 0 {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid MotionInterval var", "value", value)
				break
			}
			r.cfg.MotionInterval = v
		case "PSITime":
			v, err := strconv.Atoi(value)
			if err != nil || v < 0 {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid PSITime var", "value", value)
				break
			}
			r.cfg.PSITime = v
		case "BurstPeriod":
			v, err := strconv.Atoi(value)
			if err != nil {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid BurstPeriod param", "value", value)
				break
			}
			r.cfg.BurstPeriod = uint(v)
		case "Logging":
			switch value {
			case "Debug":
				r.cfg.LogLevel = logger.Debug
			case "Info":
				r.cfg.LogLevel = logger.Info
			case "Warning":
				r.cfg.LogLevel = logger.Warning
			case "Error":
				r.cfg.LogLevel = logger.Error
			case "Fatal":
				r.cfg.LogLevel = logger.Fatal
			default:
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid Logging param", "value", value)
			}
		case "RTMPRBMaxElements":
			v, err := strconv.Atoi(value)
			if err != nil || v < 0 {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid RTMPRBMaxElements var", "value", value)
				break
			}
			r.cfg.RBMaxElements = v
		case "RTMPRBCapacity":
			v, err := strconv.Atoi(value)
			if err != nil || v < 0 {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid RTMPRBCapacity var", "value", value)
				break
			}
			r.cfg.RBCapacity = v
		case "RTMPRBWriteTimeout":
			v, err := strconv.Atoi(value)
			if err != nil || v <= 0 {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid RTMPRBWriteTimeout var", "value", value)
				break
			}
			r.cfg.RBWriteTimeout = v
		case "MTSRBMaxElements":
			v, err := strconv.Atoi(value)
			if err != nil || v < 0 {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid MTSRBMaxElements var", "value", value)
				break
			}
			r.cfg.RBMaxElements = v
		case "MTSRBCapacity":
			v, err := strconv.Atoi(value)
			if err != nil || v < 0 {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid MTSRBCapacity var", "value", value)
				break
			}
			r.cfg.RBCapacity = v
		case "MTSRBWriteTimeout":
			v, err := strconv.Atoi(value)
			if err != nil || v <= 0 {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid MTSRBWriteTimeout var", "value", value)
				break
			}
			r.cfg.RBWriteTimeout = v
		case "CBR":
			v, ok := map[string]bool{"true": true, "false": false}[strings.ToLower(value)]
			if !ok {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid CBR var", "value", value)
				break
			}
			r.cfg.CBR = v
		case "CameraIP":
			r.cfg.CameraIP = value
		case "VBRQuality":
			v, ok := map[string]config.Quality{"standard": config.QualityStandard, "fair": config.QualityFair, "good": config.QualityGood, "great": config.QualityGreat, "excellent": config.QualityExcellent}[strings.ToLower(value)]
			if !ok {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid VBRQuality var", "value", value)
				break
			}
			r.cfg.VBRQuality = v
		case "VBRBitrate":
			v, err := strconv.Atoi(value)
			if err != nil || v <= 0 {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid VBRBitrate var", "value", value)
				break
			}
			r.cfg.VBRBitrate = v
		case "CameraChan":
			v, err := strconv.Atoi(value)
			if err != nil || (v != 1 && v != 2) {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid CameraChan var", "value", value)
				break
			}
			r.cfg.CameraChan = v
		case "ShowWindows":
			switch strings.ToLower(value) {
			case "true":
				r.cfg.ShowWindows = true
			case "false":
				r.cfg.ShowWindows = false
			default:
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid ShowWindows var", "value", value)
				break
			}
		case "MinFPS":
			v, err := strconv.ParseFloat(value, 64)
			if err != nil {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid MinFPS var", "value", value)
				break
			}
			r.cfg.MinFPS = v
		case "KNNMinArea":
			v, err := strconv.ParseFloat(value, 64)
			if err != nil {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid KNNMinArea var", "value", value)
				break
			}
			r.cfg.KNNMinArea = v
		case "KNNThreshold":
			v, err := strconv.ParseFloat(value, 64)
			if err != nil {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid KNNThreshold var", "value", value)
				break
			}
			r.cfg.KNNThreshold = v
		case "DiffThreshold":
			v, err := strconv.ParseFloat(value, 64)
			if err != nil {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid DiffThreshold var", "value", value)
				break
			}
			r.cfg.DiffThreshold = v
		case "KNNKernel":
			v, err := strconv.Atoi(value)
			if err != nil {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid KNNKernel var", "value", value)
				break
			}
			r.cfg.KNNKernel = uint(v)
		case "MOGMinArea":
			v, err := strconv.ParseFloat(value, 64)
			if err != nil {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid MOGMinArea var", "value", value)
				break
			}
			r.cfg.MOGMinArea = v
		case "MOGThreshold":
			v, err := strconv.ParseFloat(value, 64)
			if err != nil {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid MOGThreshold var", "value", value)
				break
			}
			r.cfg.MOGThreshold = v
		case "KNNHistory":
			v, err := strconv.Atoi(value)
			if err != nil || v <= 0 {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid KNNHistory var", "value", value)
				break
			}
			r.cfg.KNNHistory = uint(v)
		case "MOGHistory":
			v, err := strconv.Atoi(value)
			if err != nil || v <= 0 {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid MOGHistory var", "value", value)
				break
			}
			r.cfg.MOGHistory = uint(v)
		case "FileFPS":
			v, err := strconv.Atoi(value)
			if err != nil {
				r.cfg.Logger.Log(logger.Warning, pkg+"invalid FileFPS var", "value", value)
				break
			}
			r.cfg.FileFPS = v
		case "mode":
			r.cfg.Loop = false
			if value == "Loop" {
				r.cfg.Loop = true
			}
		}
	}
	r.cfg.Logger.Log(logger.Info, pkg+"revid config changed", "config", fmt.Sprintf("%+v", r.cfg))
	return nil
}

// processFrom is run as a routine to read from a input data source, lex and
// then send individual access units to revid's encoders.
func (r *Revid) processFrom(in device.AVDevice, delay time.Duration) {
	defer r.wg.Done()

	for l := true; l; l = r.cfg.Loop {
		err := in.Start()
		if err != nil {
			r.err <- fmt.Errorf("could not start input device: %w", err)
			return
		}

		// Lex data from input device, in, until finished or an error is encountered.
		// For a continuous source e.g. a camera or microphone, we should remain
		// in this call indefinitely unless in.Stop() is called and an io.EOF is forced.
		r.cfg.Logger.Log(logger.Info, pkg+"lexing")
		err = r.lexTo(r.filters[0], in, delay)
		switch err {
		case nil, io.EOF:
		case io.ErrUnexpectedEOF:
			r.cfg.Logger.Log(logger.Info, pkg+"unexpected EOF from input")
		default:
			r.err <- err
		}

		err = in.Stop()
		if err != nil {
			r.err <- fmt.Errorf("could not stop input source: %w", err)
		}
	}

	r.cfg.Logger.Log(logger.Info, pkg+"finished lexing")
}