feature (thumbnail): video thumbnail plugin

up until now, the stance was to refuse video thumbnail because it's too
slow but really many people don't seem to care that much about it and
keep insisting to have it.

With this solution, it's not in the base build but it gives an
option for those people to make it happen

server/ctrl/files.go

@@ -250,7 +250,9 @@ func FileCat(ctx *App, res http.ResponseWriter, req *http.Request) {
 			}
 			file, err = plgHandler.Generate(file, ctx, &res, req)
 			if err != nil {
+				if req.Context().Err() == nil {
 					Log.Debug("cat::thumbnailer '%s'", err.Error())
+				}
 				SendErrorResult(res, err)
 				return
 			}

server/plugin/plg_video_thumbnail/index.go

@@ -0,0 +1,104 @@
+package plg_video_thumbnail
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"os/exec"
+	"strings"
+
+	. "github.com/mickael-kerjean/filestash/server/common"
+)
+
+const (
+	VideoCachePath = "data/cache/video-thumbnail/"
+)
+
+var plugin_enable = func() bool {
+	return Config.Get("features.video.enable_thumbnail").Schema(func(f *FormElement) *FormElement {
+		if f == nil {
+			f = &FormElement{}
+		}
+		f.Name = "enable_thumbnail"
+		f.Type = "enable"
+		f.Target = []string{}
+		f.Description = "Enable/Disable on video thumbnail generation"
+		f.Default = false
+		return f
+	}).Bool()
+}
+
+func init() {
+	if _, err := exec.LookPath("ffmpeg"); err != nil {
+		Hooks.Register.Onload(func() {
+			Log.Warning("plg_video_thumbnail::init error=ffmpeg_not_installed")
+		})
+		return
+	}
+
+	Hooks.Register.Onload(func() {
+		if plugin_enable() == false {
+			return
+		}
+		cachePath := GetAbsolutePath(VideoCachePath)
+		os.RemoveAll(cachePath)
+		os.MkdirAll(cachePath, os.ModePerm)
+
+		Hooks.Register.Thumbnailer("video/mp4", &ffmpegThumbnail{})
+		Hooks.Register.Thumbnailer("video/x-matroska", &ffmpegThumbnail{})
+		Hooks.Register.Thumbnailer("video/x-msvideo", &ffmpegThumbnail{})
+	})
+}
+
+type ffmpegThumbnail struct{}
+
+func (this *ffmpegThumbnail) Generate(reader io.ReadCloser, ctx *App, res *http.ResponseWriter, req *http.Request) (io.ReadCloser, error) {
+	var (
+		errBuff bytes.Buffer
+		fullURL = strings.Replace(
+			fmt.Sprintf("http://127.0.0.1:%d%s?%s", Config.Get("general.port").Int(), req.URL.Path, req.URL.RawQuery),
+			"&thumbnail=true", "", 1,
+		)
+		cacheName = "thumb_" + GenerateID(ctx.Session) + "_" + QuickHash(req.URL.Query().Get("path"), 10) + ".jpeg"
+		cachePath = GetAbsolutePath(VideoCachePath, cacheName)
+	)
+
+	reader.Close()
+	thumbnail, err := os.OpenFile(cachePath, os.O_RDONLY, os.ModePerm)
+	if err == nil {
+		this.setHeader(res)
+		return thumbnail, nil
+	}
+
+	cmd := exec.CommandContext(req.Context(), "ffmpeg", []string{
+		"-headers", "cookie: " + req.Header.Get("Cookie"),
+		"-skip_frame", "nokey",
+		"-i", fullURL, "-y",
+		"-an", "-sn",
+		"-vf", "thumbnail, scale=320:320: force_original_aspect_ratio=decrease", "-vsync", "passthrough", "-frames:v", "1",
+		"-c:v", "mjpeg", cachePath,
+	}...)
+	cmd.Stderr = &errBuff
+	if err := cmd.Run(); err != nil {
+		if req.Context().Err() == nil {
+			Log.Error("plg_video_thumbnail::generate::run err=%s", errBuff.String())
+			return nil, err
+		}
+		return nil, err
+	}
+	cmd.Wait()
+	thumbnail, err = os.OpenFile(cachePath, os.O_RDONLY, os.ModePerm)
+	if err != nil {
+		Log.Error("plg_video_thumbnail::generate::open path=%s err=%s", cachePath, err.Error())
+		return nil, err
+	}
+	this.setHeader(res)
+	return thumbnail, nil
+}
+
+func (this *ffmpegThumbnail) setHeader(res *http.ResponseWriter) {
+	(*res).Header().Set("Content-Type", "image/jpeg")
+	(*res).Header().Set("Cache-Control", fmt.Sprintf("max-age=%d", 3600*12))
+}

server/plugin/plg_video_transcoder/index.go

@@ -32,14 +32,19 @@ var (
 )
 
 func init() {
-	ffmpegIsInstalled := false
+	if _, err := exec.LookPath("ffmpeg"); err != nil {
-	ffprobeIsInstalled := false
+		Hooks.Register.Onload(func() {
-	if _, err := exec.LookPath("ffmpeg"); err == nil {
+			Log.Warning("plg_video_thumbnail::init error=ffmpeg_not_installed")
-		ffmpegIsInstalled = true
+		})
+		return
 	}
-	if _, err := exec.LookPath("ffprobe"); err == nil {
+	if _, err := exec.LookPath("ffprobe"); err != nil {
-		ffprobeIsInstalled = true
+		Hooks.Register.Onload(func() {
+			Log.Warning("plg_video_thumbnail::init error=ffprobe_not_installed")
+		})
+		return
 	}
+
 	plugin_enable = func() bool {
 		return Config.Get("features.video.enable_transcoder").Schema(func(f *FormElement) *FormElement {
 			if f == nil {
@@ -50,9 +55,6 @@ func init() {
 			f.Target = []string{"transcoding_blacklist_format"}
 			f.Description = "Enable/Disable on demand video transcoding. The transcoder"
 			f.Default = true
-			if ffmpegIsInstalled == false || ffprobeIsInstalled == false {
-				f.Default = false
-			}
 			return f
 		}).Bool()
 	}
@@ -80,13 +82,6 @@ func init() {
 		cachePath := GetAbsolutePath(VideoCachePath)
 		os.RemoveAll(cachePath)
 		os.MkdirAll(cachePath, os.ModePerm)
-		if ffmpegIsInstalled == false {
-			Log.Warning("[plugin video transcoder] ffmpeg needs to be installed")
-			return
-		} else if ffprobeIsInstalled == false {
-			Log.Warning("[plugin video transcoder] ffprobe needs to be installed")
-			return
-		}
 	})
 
 	Hooks.Register.HttpEndpoint(func(r *mux.Router, app *App) error {