From 9ebec675b58164b4cbd8b033cf95610ca9005b86 Mon Sep 17 00:00:00 2001
From: Gabe Kangas <gabek@real-ity.com>
Date: Wed, 10 Jun 2020 01:16:17 -0700
Subject: [PATCH] Generate a static thumbnail png every 20s

---
 main.go               |  8 +++--
 thumbnailGenerator.go | 72 +++++++++++++++++++++++++++++++++++++++++++
 webroot/index.html    |  4 +--
 3 files changed, 80 insertions(+), 4 deletions(-)
 create mode 100644 thumbnailGenerator.go

diff --git a/main.go b/main.go
index 53fd219ce..6c4e816b4 100644
--- a/main.go
+++ b/main.go
@@ -13,14 +13,13 @@ var configuration = getConfig()
 var server *Server
 
 var online = false
+var usingExternalStorage = false
 
 func main() {
 	log.Println("Starting up.  Please wait...")
 	resetDirectories(configuration)
 	checkConfig(configuration)
 
-	var usingExternalStorage = false
-
 	if configuration.IPFS.Enabled {
 		storage = &IPFSStorage{}
 		usingExternalStorage = true
@@ -66,6 +65,11 @@ func getStatus(w http.ResponseWriter, r *http.Request) {
 
 func streamConnected() {
 	online = true
+	chunkPath := configuration.PublicHLSPath
+	if usingExternalStorage {
+		chunkPath = configuration.PrivateHLSPath
+	}
+	startThumbnailGenerator(chunkPath)
 }
 
 func streamDisconnected() {
diff --git a/thumbnailGenerator.go b/thumbnailGenerator.go
new file mode 100644
index 000000000..3de76b3bf
--- /dev/null
+++ b/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)
+}
diff --git a/webroot/index.html b/webroot/index.html
index 4663ac23e..4ff89b8d1 100644
--- a/webroot/index.html
+++ b/webroot/index.html
@@ -31,10 +31,10 @@
         id="video"
         class="video-js vjs-theme-fantasy"
         preload="auto"
-        poster="https://picsum.photos/900/600"
+        poster="/thumbnail.png"
         autoplay
         controls
-        style="width: 100%;"
+        style="width: 100%; height: 600px;"
         data-setup='{}'
       >
       <source src="hls/stream.m3u8" type="application/x-mpegURL"/>