Generate a static thumbnail png every 20s

thumbnailGenerator.go

@@ -0,0 +1,72 @@
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path"
+	"time"
+)
+
+func startThumbnailGenerator(chunkPath string) {
+	// Every 20 seconds create a thumbnail from the most
+	// recent video segment.
+	ticker := time.NewTicker(20 * time.Second)
+	quit := make(chan struct{})
+	go func() {
+		for {
+			select {
+			case <-ticker.C:
+				fireThumbnailGenerator(chunkPath)
+			case <-quit:
+				ticker.Stop()
+				return
+			}
+		}
+	}()
+}
+
+func fireThumbnailGenerator(chunkPath string) {
+	framePath := path.Join(chunkPath, "0")
+	files, err := ioutil.ReadDir(framePath)
+	outputFile := path.Join("webroot", "thumbnail.png")
+
+	// fmt.Println("Generating thumbnail from", framePath, "to", outputFile)
+
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+
+	var modTime time.Time
+	var names []string
+	for _, fi := range files {
+		if path.Ext(fi.Name()) != ".ts" {
+			continue
+		}
+
+		if fi.Mode().IsRegular() {
+			if !fi.ModTime().Before(modTime) {
+				if fi.ModTime().After(modTime) {
+					modTime = fi.ModTime()
+					names = names[:0]
+				}
+				names = append(names, fi.Name())
+			}
+		}
+	}
+
+	if len(names) == 0 {
+		return
+	}
+
+	mostRecentFile := path.Join(framePath, names[0])
+
+	ffmpegCmd := "ffmpeg -y -i " + mostRecentFile + " -ss 00:00:01.000 -vframes 1 " + outputFile
+
+	// fmt.Println(ffmpegCmd)
+
+	_, err = exec.Command("sh", "-c", ffmpegCmd).Output()
+	verifyError(err)
+}