commit 1f3d87d37fb0639bfbb9dd831047eaf2b41b9205
Author: Magnus Åhall <magnus.ahall@gibon.se>
Date:   Thu Oct 10 09:05:32 2024 +0200

    Initial commit

diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..d2786b1
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module timelapse
+
+go 1.23.0
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..778fe20
--- /dev/null
+++ b/main.go
@@ -0,0 +1,188 @@
+package main
+
+import (
+	// Standard
+	"flag"
+	"fmt"
+	"os"
+	"os/exec"
+	"path"
+	"regexp"
+	"slices"
+	"strconv"
+	"time"
+)
+
+var (
+	fromHour     int
+	toHour       int
+	startDir     string
+	outFilename  string
+	framerate    string
+	rxpFilename  *regexp.Regexp
+	rxpTimestamp *regexp.Regexp
+)
+
+func parseCommandLine() {
+	workDir, err := os.Getwd()
+	if err != nil {
+		panic(err)
+	}
+	flag.IntVar(&fromHour, "from", 0, "Hour each day to start picking images from")
+	flag.IntVar(&toHour, "to", 24, "Hour each day to start picking images up to")
+	flag.StringVar(&startDir, "dir", workDir, "Directory to find date folders in")
+	flag.StringVar(&outFilename, "out", "timelapse.mp4", "path and filename for the final timelapse video")
+	flag.StringVar(&framerate, "framerate", "60", "Framerate")
+	flag.Parse()
+
+	rxpFilename = regexp.MustCompile(`(?i)^(\d+)\.(?:jpg|png)$`)
+	rxpTimestamp = regexp.MustCompile(`/(\d+)\.(?:\S{3})$`)
+}
+
+func findFiles(dir string) (files []string) { // {{{
+	entries, err := os.ReadDir(dir)
+	if err != nil {
+		return
+	}
+
+	for _, entry := range entries {
+		if entry.IsDir() {
+			files = append(
+				files,
+				findFiles(path.Join(dir, entry.Name()))...,
+			)
+		} else {
+			if validateFilename(entry.Name()) {
+				files = append(files, path.Join(dir, entry.Name()))
+			}
+		}
+	}
+
+	return
+} // }}}
+func validateFilename(fname string) bool { // {{{
+	// fname is just a bunch of numbers with a .png or .jpg postfix.
+	if !rxpFilename.MatchString(fname) {
+		return false
+	}
+
+	t := filenameToTime(fname, false)
+	return t.Hour() >= fromHour && t.Hour() <= toHour
+} // }}}
+func filenameToTime(fname string, fnameWithPath bool) time.Time { // {{{
+	var tp []string
+	if fnameWithPath {
+		tp = rxpTimestamp.FindStringSubmatch(fname)
+	} else {
+		tp = rxpFilename.FindStringSubmatch(fname)
+	}
+	tsi, _ := strconv.Atoi(tp[1])
+	ts := int64(tsi)
+	t := time.Unix(int64(ts), 0)
+	sweden, _ := time.LoadLocation("Europe/Stockholm")
+	t = t.In(sweden)
+	return t
+} // }}}
+func sortFiles(a, b string) int { // {{{
+	as := rxpTimestamp.FindStringSubmatch(a)
+	bs := rxpTimestamp.FindStringSubmatch(b)
+	an, _ := strconv.Atoi(as[1])
+	bn, _ := strconv.Atoi(bs[1])
+	switch {
+	case an < bn:
+		return -1
+	case an > bn:
+		return 1
+	}
+	return 0
+} // }}}
+
+func separateDays(files []string) *map[string][]string { // {{{
+	days := make(map[string][]string, 128)
+
+	var t time.Time
+	var date string
+	var fnames []string
+	var found bool
+	for _, f := range files {
+		t = filenameToTime(f, true)
+		date = t.Format("2006-01-02")
+
+		fnames, found = days[date]
+		if !found {
+			fnames = []string{}
+		}
+		fnames = append(fnames, f)
+		days[date] = fnames
+	}
+
+	return &days
+} // }}}
+func filesToSequenceFile(fname string, files []string) { // {{{
+	out, err := os.OpenFile(fname, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0644)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+	defer out.Close()
+
+	for _, f := range files {
+		_, err = out.WriteString(
+			fmt.Sprintf("file '%s'\n", f),
+		)
+		if err != nil {
+			fmt.Fprintln(os.Stderr, err)
+			os.Exit(1)
+		}
+	}
+} // }}}
+func timelapse(date string, files []string) { // {{{
+	sequenceFile := fmt.Sprintf("/tmp/timelapse/sequence_%s", date)
+	videoFile := fmt.Sprintf("/tmp/timelapse/video_%s.mp4", date)
+	text := fmt.Sprintf("drawtext=text='%s':fontsize=30:x=10:y=10:fontcolor=#71b045:bordercolor=black:borderw=1", date)
+
+	filesToSequenceFile(sequenceFile, files)
+	os.Remove(videoFile)
+	ffmpeg := exec.Command("ffmpeg", "-safe", "0", "-f", "concat", "-i", sequenceFile, "-filter_complex", text, "-framerate", framerate, "-c:v", "libx264", "-crf", "23", videoFile)
+	out, err := ffmpeg.CombinedOutput()
+	if err != nil {
+		fmt.Printf("%s\n", out)
+		panic(err)
+	}
+} // }}}
+func concatVideos(unsortedDates []string) {
+	fname := "/tmp/timelapse/sequence_all"
+	var videos []string
+
+	for _, date := range unsortedDates {
+		videos = append(videos, "/tmp/timelapse/video_"+date+".mp4")
+	}
+	slices.Sort(videos)
+
+	filesToSequenceFile(fname, videos)
+	os.Remove(outFilename)
+	ffmpeg := exec.Command("ffmpeg", "-safe", "0", "-f", "concat", "-i", fname, "-c", "copy", outFilename)
+	out, err := ffmpeg.CombinedOutput()
+	if err != nil {
+		fmt.Printf("%s\n", out)
+		panic(err)
+	}
+}
+
+func main() {
+	parseCommandLine()
+	files := findFiles(startDir)
+	slices.SortStableFunc(files, sortFiles)
+	sortedDays := separateDays(files)
+
+	os.Mkdir("/tmp/timelapse", 0755)
+	var dates []string
+	for date, files := range *sortedDays {
+		fmt.Printf("Create timelapse for %s\n", date)
+		dates = append(dates, date)
+		timelapse(date, files)
+	}
+
+	fmt.Println("Assemble day videos to complete timelapse")
+	concatVideos(dates)
+}