Added scene preview generator

manager/generator.go

@@ -0,0 +1,62 @@
+package manager
+
+import (
+	"fmt"
+	"github.com/stashapp/stash/ffmpeg"
+	"github.com/stashapp/stash/logger"
+	"github.com/stashapp/stash/utils"
+	"os/exec"
+	"strconv"
+)
+
+type Generator struct {
+	ChunkCount     int
+	FrameRate      float64
+	NumberOfFrames int
+	NthFrame       int
+
+	VideoFile ffmpeg.VideoFile
+}
+
+func newGenerator(videoFile ffmpeg.VideoFile) (*Generator, error) {
+	exists, err := utils.FileExists(videoFile.Path)
+	if !exists {
+		logger.Errorf("video file not found")
+		return nil, err
+	}
+
+	generator := &Generator{VideoFile: videoFile}
+	return generator, nil
+}
+
+func (g *Generator) configure() error {
+	videoStream := g.VideoFile.VideoStream
+	if videoStream == nil {
+		return fmt.Errorf("missing video stream")
+	}
+
+	var framerate float64
+	if g.VideoFile.FrameRate == 0 {
+		framerate, _ = strconv.ParseFloat(videoStream.RFrameRate, 64)
+	} else {
+		framerate = g.VideoFile.FrameRate
+	}
+	g.FrameRate = framerate
+
+	numberOfFrames, _ := strconv.Atoi(videoStream.NbFrames)
+	if numberOfFrames == 0 {
+		command := `ffmpeg -nostats -i `+g.VideoFile.Path+` -vcodec copy -f rawvideo -y /dev/null 2>&1 | \
+                       grep frame | \
+                       awk '{split($0,a,"fps")}END{print a[1]}' | \
+                       sed 's/.*= *//'`
+		commandResult, _ := exec.Command(command).Output()
+		numberOfFrames, _ := strconv.Atoi(string(commandResult))
+		if numberOfFrames == 0 { // TODO: test
+			numberOfFrames = int(framerate * g.VideoFile.Duration)
+		}
+	}
+	g.NumberOfFrames = numberOfFrames
+	g.NthFrame = g.NumberOfFrames / g.ChunkCount
+
+	return nil
+}