Allow customisation of preview generation (#673)

* Add generate-specific options
* Include no-cache in preview response

graphql/documents/data/config.graphql

@@ -3,6 +3,10 @@ fragment ConfigGeneralData on ConfigGeneralResult {
   databasePath
   generatedPath
   cachePath
+  previewSegments
+  previewSegmentDuration
+  previewExcludeStart
+  previewExcludeEnd
   previewPreset
   maxTranscodeSize
   maxStreamingTranscodeSize

graphql/schema/types/config.graphql

@@ -26,6 +26,14 @@ input ConfigGeneralInput {
   generatedPath: String
   """Path to cache"""
   cachePath: String
+  """Number of segments in a preview file"""
+  previewSegments: Int
+  """Preview segment duration, in seconds"""
+  previewSegmentDuration: Float
+  """Duration of start of video to exclude when generating previews"""
+  previewExcludeStart: String
+  """Duration of end of video to exclude when generating previews"""
+  previewExcludeEnd: String
   """Preset when generating preview"""
   previewPreset: PreviewPreset
   """Max generated transcode size"""
@@ -61,6 +69,14 @@ type ConfigGeneralResult {
   generatedPath: String!
   """Path to cache"""
   cachePath: String!
+  """Number of segments in a preview file"""
+  previewSegments: Int!
+  """Preview segment duration, in seconds"""
+  previewSegmentDuration: Float!
+  """Duration of start of video to exclude when generating previews"""
+  previewExcludeStart: String!
+  """Duration of end of video to exclude when generating previews"""
+  previewExcludeEnd: String!
   """Preset when generating preview"""
   previewPreset: PreviewPreset!
   """Max generated transcode size"""

graphql/schema/types/metadata.graphql

@@ -2,6 +2,7 @@ input GenerateMetadataInput {
   sprites: Boolean!
   previews: Boolean!
   imagePreviews: Boolean!
+  previewOptions: GeneratePreviewOptionsInput
   markers: Boolean!
   transcodes: Boolean!
   """gallery thumbnails for cache usage"""
@@ -18,6 +19,19 @@ input GenerateMetadataInput {
   overwrite: Boolean
 }
 
+input GeneratePreviewOptionsInput {
+  """Number of segments in a preview file"""
+  previewSegments: Int
+  """Preview segment duration, in seconds"""
+  previewSegmentDuration: Float
+  """Duration of start of video to exclude when generating previews"""
+  previewExcludeStart: String
+  """Duration of end of video to exclude when generating previews"""
+  previewExcludeEnd: String
+  """Preset when generating preview"""
+  previewPreset: PreviewPreset
+}
+
 input ScanMetadataInput {
   useFileMetadata: Boolean!
 }

pkg/api/resolver_mutation_configure.go

@@ -45,6 +45,18 @@ func (r *mutationResolver) ConfigureGeneral(ctx context.Context, input models.Co
 		config.Set(config.Cache, input.CachePath)
 	}
 
+	if input.PreviewSegments != nil {
+		config.Set(config.PreviewSegments, *input.PreviewSegments)
+	}
+	if input.PreviewSegmentDuration != nil {
+		config.Set(config.PreviewSegmentDuration, *input.PreviewSegmentDuration)
+	}
+	if input.PreviewExcludeStart != nil {
+		config.Set(config.PreviewExcludeStart, *input.PreviewExcludeStart)
+	}
+	if input.PreviewExcludeEnd != nil {
+		config.Set(config.PreviewExcludeEnd, *input.PreviewExcludeEnd)
+	}
 	if input.PreviewPreset != nil {
 		config.Set(config.PreviewPreset, input.PreviewPreset.String())
 	}

pkg/api/resolver_query_configuration.go

@@ -46,6 +46,10 @@ func makeConfigGeneralResult() *models.ConfigGeneralResult {
 		DatabasePath:              config.GetDatabasePath(),
 		GeneratedPath:             config.GetGeneratedPath(),
 		CachePath:                 config.GetCachePath(),
+		PreviewSegments:           config.GetPreviewSegments(),
+		PreviewSegmentDuration:    config.GetPreviewSegmentDuration(),
+		PreviewExcludeStart:       config.GetPreviewExcludeStart(),
+		PreviewExcludeEnd:         config.GetPreviewExcludeEnd(),
 		PreviewPreset:             config.GetPreviewPreset(),
 		MaxTranscodeSize:          &maxTranscodeSize,
 		MaxStreamingTranscodeSize: &maxStreamingTranscodeSize,

pkg/api/routes_scene.go

@@ -187,7 +187,7 @@ func (rs sceneRoutes) Screenshot(w http.ResponseWriter, r *http.Request) {
 func (rs sceneRoutes) Preview(w http.ResponseWriter, r *http.Request) {
 	scene := r.Context().Value(sceneKey).(*models.Scene)
 	filepath := manager.GetInstance().Paths.Scene.GetStreamPreviewPath(scene.Checksum)
-	http.ServeFile(w, r, filepath)
+	utils.ServeFileNoCache(w, r, filepath)
 }
 
 func (rs sceneRoutes) Webp(w http.ResponseWriter, r *http.Request) {

pkg/ffmpeg/encoder_scene_preview_chunk.go

@@ -8,7 +8,8 @@ import (
 )
 
 type ScenePreviewChunkOptions struct {
-	Time       int
+	StartTime  float64
+	Duration   float64
 	Width      int
 	OutputPath string
 }
@@ -17,9 +18,9 @@ func (e *Encoder) ScenePreviewVideoChunk(probeResult VideoFile, options ScenePre
 	args := []string{
 		"-v", "error",
 		"-xerror",
-		"-ss", strconv.Itoa(options.Time),
+		"-ss", strconv.FormatFloat(options.StartTime, 'f', 2, 64),
 		"-i", probeResult.Path,
-		"-t", "0.75",
+		"-t", strconv.FormatFloat(options.Duration, 'f', 2, 64),
 		"-max_muxing_queue_size", "1024", // https://trac.ffmpeg.org/ticket/6375
 		"-y",
 		"-c:v", "libx264",

pkg/manager/config/config.go

@@ -32,6 +32,18 @@ const PreviewPreset = "preview_preset"
 const MaxTranscodeSize = "max_transcode_size"
 const MaxStreamingTranscodeSize = "max_streaming_transcode_size"
 
+const PreviewSegmentDuration = "preview_segment_duration"
+const previewSegmentDurationDefault = 0.75
+
+const PreviewSegments = "preview_segments"
+const previewSegmentsDefault = 12
+
+const PreviewExcludeStart = "preview_exclude_start"
+const previewExcludeStartDefault = "0"
+
+const PreviewExcludeEnd = "preview_exclude_end"
+const previewExcludeEndDefault = "0"
+
 const Host = "host"
 const Port = "port"
 const ExternalHost = "external_host"
@@ -158,6 +170,36 @@ func GetExternalHost() string {
 	return viper.GetString(ExternalHost)
 }
 
+// GetPreviewSegmentDuration returns the duration of a single segment in a
+// scene preview file, in seconds.
+func GetPreviewSegmentDuration() float64 {
+	return viper.GetFloat64(PreviewSegmentDuration)
+}
+
+// GetPreviewSegments returns the amount of segments in a scene preview file.
+func GetPreviewSegments() int {
+	return viper.GetInt(PreviewSegments)
+}
+
+// GetPreviewExcludeStart returns the configuration setting string for
+// excluding the start of scene videos for preview generation. This can
+// be in two possible formats. A float value is interpreted as the amount
+// of seconds to exclude from the start of the video before it is included
+// in the preview. If the value is suffixed with a '%' character (for example
+// '2%'), then it is interpreted as a proportion of the total video duration.
+func GetPreviewExcludeStart() string {
+	return viper.GetString(PreviewExcludeStart)
+}
+
+// GetPreviewExcludeEnd returns the configuration setting string for
+// excluding the end of scene videos for preview generation. A float value
+// is interpreted as the amount of seconds to exclude from the end of the video
+// when generating previews. If the value is suffixed with a '%' character,
+// then it is interpreted as a proportion of the total video duration.
+func GetPreviewExcludeEnd() string {
+	return viper.GetString(PreviewExcludeEnd)
+}
+
 // GetPreviewPreset returns the preset when generating previews. Defaults to
 // Slow.
 func GetPreviewPreset() models.PreviewPreset {
@@ -371,6 +413,13 @@ func IsValid() bool {
 	return setPaths
 }
 
+func setDefaultValues() {
+	viper.SetDefault(PreviewSegmentDuration, previewSegmentDurationDefault)
+	viper.SetDefault(PreviewSegments, previewSegmentsDefault)
+	viper.SetDefault(PreviewExcludeStart, previewExcludeStartDefault)
+	viper.SetDefault(PreviewExcludeEnd, previewExcludeEndDefault)
+}
+
 // SetInitialConfig fills in missing required config fields
 func SetInitialConfig() error {
 	// generate some api keys
@@ -386,5 +435,7 @@ func SetInitialConfig() error {
 		Set(SessionStoreKey, sessionStoreKey)
 	}
 
+	setDefaultValues()
+
 	return Write()
 }

pkg/manager/generator.go

@@ -7,6 +7,7 @@ import (
 	"os/exec"
 	"runtime"
 	"strconv"
+	"strings"
 
 	"github.com/stashapp/stash/pkg/ffmpeg"
 	"github.com/stashapp/stash/pkg/logger"
@@ -17,7 +18,13 @@ type GeneratorInfo struct {
 	ChunkCount     int
 	FrameRate      float64
 	NumberOfFrames int
-	NthFrame       int
+
+	// NthFrame used for sprite generation
+	NthFrame int
+
+	ChunkDuration float64
+	ExcludeStart  string
+	ExcludeEnd    string
 
 	VideoFile ffmpeg.VideoFile
 }
@@ -33,12 +40,7 @@ func newGeneratorInfo(videoFile ffmpeg.VideoFile) (*GeneratorInfo, error) {
 	return generator, nil
 }
 
-func (g *GeneratorInfo) configure() error {
+func (g *GeneratorInfo) calculateFrameRate(videoStream *ffmpeg.FFProbeStream) 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)
@@ -94,7 +96,54 @@ func (g *GeneratorInfo) configure() error {
 
 	g.FrameRate = framerate
 	g.NumberOfFrames = numberOfFrames
+
+	return nil
+}
+
+func (g *GeneratorInfo) configure() error {
+	videoStream := g.VideoFile.VideoStream
+	if videoStream == nil {
+		return fmt.Errorf("missing video stream")
+	}
+
+	if err := g.calculateFrameRate(videoStream); err != nil {
+		return err
+	}
+
 	g.NthFrame = g.NumberOfFrames / g.ChunkCount
 
 	return nil
 }
+
+func (g GeneratorInfo) getExcludeValue(v string) float64 {
+	if strings.HasSuffix(v, "%") && len(v) > 1 {
+		// proportion of video duration
+		v = v[0 : len(v)-1]
+		prop, _ := strconv.ParseFloat(v, 64)
+		return prop / 100.0 * g.VideoFile.Duration
+	}
+
+	prop, _ := strconv.ParseFloat(v, 64)
+	return prop
+}
+
+// getStepSizeAndOffset calculates the step size for preview generation and
+// the starting offset.
+//
+// Step size is calculated based on the duration of the video file, minus the
+// excluded duration. The offset is based on the ExcludeStart. If the total
+// excluded duration exceeds the duration of the video, then offset is 0, and
+// the video duration is used to calculate the step size.
+func (g GeneratorInfo) getStepSizeAndOffset() (stepSize float64, offset float64) {
+	duration := g.VideoFile.Duration
+	excludeStart := g.getExcludeValue(g.ExcludeStart)
+	excludeEnd := g.getExcludeValue(g.ExcludeEnd)
+
+	if duration > excludeStart+excludeEnd {
+		duration = duration - excludeStart - excludeEnd
+		offset = excludeStart
+	}
+
+	stepSize = duration / float64(g.ChunkCount)
+	return
+}

pkg/manager/generator_preview.go

@@ -36,9 +36,6 @@ func NewPreviewGenerator(videoFile ffmpeg.VideoFile, videoFilename string, image
 		return nil, err
 	}
 	generator.ChunkCount = 12 // 12 segments to the preview
-	if err := generator.configure(); err != nil {
-		return nil, err
-	}
 
 	return &PreviewGenerator{
 		Info:            generator,
@@ -53,6 +50,11 @@ func NewPreviewGenerator(videoFile ffmpeg.VideoFile, videoFilename string, image
 
 func (g *PreviewGenerator) Generate() error {
 	logger.Infof("[generator] generating scene preview for %s", g.Info.VideoFile.Path)
+
+	if err := g.Info.configure(); err != nil {
+		return err
+	}
+
 	encoder := ffmpeg.NewEncoder(instance.FFMPEGPath)
 
 	if err := g.generateConcatFile(); err != nil {
@@ -95,15 +97,17 @@ func (g *PreviewGenerator) generateVideo(encoder *ffmpeg.Encoder) error {
 		return nil
 	}
 
-	stepSize := int(g.Info.VideoFile.Duration / float64(g.Info.ChunkCount))
+	stepSize, offset := g.Info.getStepSizeAndOffset()
+
 	for i := 0; i < g.Info.ChunkCount; i++ {
-		time := i * stepSize
+		time := offset + (float64(i) * stepSize)
 		num := fmt.Sprintf("%.3d", i)
 		filename := "preview" + num + ".mp4"
 		chunkOutputPath := instance.Paths.Generated.GetTmpPath(filename)
 
 		options := ffmpeg.ScenePreviewChunkOptions{
-			Time:       time,
+			StartTime:  time,
+			Duration:   g.Info.ChunkDuration,
 			Width:      640,
 			OutputPath: chunkOutputPath,
 		}

pkg/manager/manager.go

@@ -81,6 +81,8 @@ func initConfig() {
 	}
 	logger.Infof("using config file: %s", viper.ConfigFileUsed())
 
+	config.SetInitialConfig()
+
 	viper.SetDefault(config.Database, paths.GetDefaultDatabaseFilePath())
 
 	// Set generated to the metadata path for backwards compat

pkg/manager/manager_tasks.go

@@ -167,6 +167,33 @@ func (s *singleton) Export() {
 	}()
 }
 
+func setGeneratePreviewOptionsInput(optionsInput *models.GeneratePreviewOptionsInput) {
+	if optionsInput.PreviewSegments == nil {
+		val := config.GetPreviewSegments()
+		optionsInput.PreviewSegments = &val
+	}
+
+	if optionsInput.PreviewSegmentDuration == nil {
+		val := config.GetPreviewSegmentDuration()
+		optionsInput.PreviewSegmentDuration = &val
+	}
+
+	if optionsInput.PreviewExcludeStart == nil {
+		val := config.GetPreviewExcludeStart()
+		optionsInput.PreviewExcludeStart = &val
+	}
+
+	if optionsInput.PreviewExcludeEnd == nil {
+		val := config.GetPreviewExcludeEnd()
+		optionsInput.PreviewExcludeEnd = &val
+	}
+
+	if optionsInput.PreviewPreset == nil {
+		val := config.GetPreviewPreset()
+		optionsInput.PreviewPreset = &val
+	}
+}
+
 func (s *singleton) Generate(input models.GenerateMetadataInput) {
 	if s.Status.Status != Idle {
 		return
@@ -181,8 +208,6 @@ func (s *singleton) Generate(input models.GenerateMetadataInput) {
 	//this.job.total = await ObjectionUtils.getCount(Scene);
 	instance.Paths.Generated.EnsureTmpDir()
 
-	preset := config.GetPreviewPreset().String()
-
 	galleryIDs := utils.StringSliceToIntSlice(input.GalleryIDs)
 	sceneIDs := utils.StringSliceToIntSlice(input.SceneIDs)
 	markerIDs := utils.StringSliceToIntSlice(input.MarkerIDs)
@@ -251,6 +276,12 @@ func (s *singleton) Generate(input models.GenerateMetadataInput) {
 			overwrite = *input.Overwrite
 		}
 
+		generatePreviewOptions := input.PreviewOptions
+		if generatePreviewOptions == nil {
+			generatePreviewOptions = &models.GeneratePreviewOptionsInput{}
+		}
+		setGeneratePreviewOptionsInput(generatePreviewOptions)
+
 		for i, scene := range scenes {
 			s.Status.setProgress(i, total)
 			if s.Status.stopping {
@@ -276,7 +307,12 @@ func (s *singleton) Generate(input models.GenerateMetadataInput) {
 			}
 
 			if input.Previews {
-				task := GeneratePreviewTask{Scene: *scene, ImagePreview: input.ImagePreviews, PreviewPreset: preset, Overwrite: overwrite}
+				task := GeneratePreviewTask{
+					Scene:        *scene,
+					ImagePreview: input.ImagePreviews,
+					Options:      *generatePreviewOptions,
+					Overwrite:    overwrite,
+				}
 				go task.Start(&wg)
 			}
 

pkg/manager/task_generate_preview.go

@@ -10,10 +10,12 @@ import (
 )
 
 type GeneratePreviewTask struct {
-	Scene         models.Scene
+	Scene        models.Scene
-	ImagePreview  bool
+	ImagePreview bool
-	PreviewPreset string
+
-	Overwrite     bool
+	Options models.GeneratePreviewOptionsInput
+
+	Overwrite bool
 }
 
 func (t *GeneratePreviewTask) Start(wg *sync.WaitGroup) {
@@ -32,13 +34,19 @@ func (t *GeneratePreviewTask) Start(wg *sync.WaitGroup) {
 		return
 	}
 
-	generator, err := NewPreviewGenerator(*videoFile, videoFilename, imageFilename, instance.Paths.Generated.Screenshots, true, t.ImagePreview, t.PreviewPreset)
+	generator, err := NewPreviewGenerator(*videoFile, videoFilename, imageFilename, instance.Paths.Generated.Screenshots, true, t.ImagePreview, t.Options.PreviewPreset.String())
 	if err != nil {
 		logger.Errorf("error creating preview generator: %s", err.Error())
 		return
 	}
 	generator.Overwrite = t.Overwrite
 
+	// set the preview generation configuration from the global config
+	generator.Info.ChunkCount = *t.Options.PreviewSegments
+	generator.Info.ChunkDuration = *t.Options.PreviewSegmentDuration
+	generator.Info.ExcludeStart = *t.Options.PreviewExcludeStart
+	generator.Info.ExcludeEnd = *t.Options.PreviewExcludeEnd
+
 	if err := generator.Generate(); err != nil {
 		logger.Errorf("error generating preview: %s", err.Error())
 		return

pkg/utils/file.go

@@ -3,13 +3,15 @@ package utils
 import (
 	"archive/zip"
 	"fmt"
-	"github.com/h2non/filetype"
-	"github.com/h2non/filetype/types"
 	"io/ioutil"
 	"math"
+	"net/http"
 	"os"
 	"os/user"
 	"path/filepath"
+
+	"github.com/h2non/filetype"
+	"github.com/h2non/filetype/types"
 )
 
 // FileType uses the filetype package to determine the given file path's type
@@ -219,3 +221,11 @@ func GetParent(path string) *string {
 		return &parentPath
 	}
 }
+
+// ServeFileNoCache serves the provided file, ensuring that the response
+// contains headers to prevent caching.
+func ServeFileNoCache(w http.ResponseWriter, r *http.Request, filepath string) {
+	w.Header().Add("Cache-Control", "no-cache")
+
+	http.ServeFile(w, r, filepath)
+}

ui/v2.5/src/components/Changelog/versions/v030.tsx

@@ -13,6 +13,7 @@ const markup = `
 *  Add support for parent/child studios.
 
 ### 🎨 Improvements
+*  Allow customisation of preview video generation.
 *  Add support for live transcoding in Safari.
 *  Add mapped and fixed post-processing scraping options.
 *  Add random sorting for performers.

ui/v2.5/src/components/Scenes/SceneGenerateDialog.tsx

@@ -1,8 +1,12 @@
-import React, { useState } from "react";
+import React, { useState, useEffect } from "react";
-import { Form } from "react-bootstrap";
+import { Form, Button, Collapse } from "react-bootstrap";
-import { mutateMetadataGenerate } from "src/core/StashService";
+import {
-import { Modal } from "src/components/Shared";
+  mutateMetadataGenerate,
+  useConfiguration,
+} from "src/core/StashService";
+import { Modal, Icon } from "src/components/Shared";
 import { useToast } from "src/hooks";
+import * as GQL from "src/core/generated-graphql";
 
 interface ISceneGenerateDialogProps {
   selectedIds: string[];
@@ -12,6 +16,8 @@ interface ISceneGenerateDialogProps {
 export const SceneGenerateDialog: React.FC<ISceneGenerateDialogProps> = (
   props: ISceneGenerateDialogProps
 ) => {
+  const { data, error, loading } = useConfiguration();
+
   const [sprites, setSprites] = useState(true);
   const [previews, setPreviews] = useState(true);
   const [markers, setMarkers] = useState(true);
@@ -19,8 +25,37 @@ export const SceneGenerateDialog: React.FC<ISceneGenerateDialogProps> = (
   const [overwrite, setOverwrite] = useState(true);
   const [imagePreviews, setImagePreviews] = useState(false);
 
+  const [previewSegments, setPreviewSegments] = useState<number>(0);
+  const [previewSegmentDuration, setPreviewSegmentDuration] = useState<number>(
+    0
+  );
+  const [previewExcludeStart, setPreviewExcludeStart] = useState<
+    string | undefined
+  >(undefined);
+  const [previewExcludeEnd, setPreviewExcludeEnd] = useState<
+    string | undefined
+  >(undefined);
+  const [previewPreset, setPreviewPreset] = useState<string>(
+    GQL.PreviewPreset.Slow
+  );
+
+  const [previewOptionsOpen, setPreviewOptionsOpen] = useState(false);
+
   const Toast = useToast();
 
+  useEffect(() => {
+    if (!data?.configuration) return;
+
+    const conf = data.configuration;
+    if (conf.general) {
+      setPreviewSegments(conf.general.previewSegments);
+      setPreviewSegmentDuration(conf.general.previewSegmentDuration);
+      setPreviewExcludeStart(conf.general.previewExcludeStart);
+      setPreviewExcludeEnd(conf.general.previewExcludeEnd);
+      setPreviewPreset(conf.general.previewPreset);
+    }
+  }, [data]);
+
   async function onGenerate() {
     try {
       await mutateMetadataGenerate({
@@ -32,6 +67,13 @@ export const SceneGenerateDialog: React.FC<ISceneGenerateDialogProps> = (
         thumbnails: false,
         overwrite,
         sceneIDs: props.selectedIds,
+        previewOptions: {
+          previewPreset: (previewPreset as GQL.PreviewPreset) ?? undefined,
+          previewSegments,
+          previewSegmentDuration,
+          previewExcludeStart,
+          previewExcludeEnd,
+        },
       });
       Toast.success({ content: "Started generating" });
     } catch (e) {
@@ -41,6 +83,15 @@ export const SceneGenerateDialog: React.FC<ISceneGenerateDialogProps> = (
     }
   }
 
+  if (error) {
+    Toast.error(error);
+    props.onClose();
+  }
+
+  if (loading) {
+    return <></>;
+  }
+
   return (
     <Modal
       show
@@ -72,6 +123,109 @@ export const SceneGenerateDialog: React.FC<ISceneGenerateDialogProps> = (
               className="ml-2 flex-grow"
             />
           </div>
+          <div className="my-2">
+            <Button
+              onClick={() => setPreviewOptionsOpen(!previewOptionsOpen)}
+              className="minimal pl-0 no-focus"
+            >
+              <Icon
+                icon={previewOptionsOpen ? "chevron-down" : "chevron-right"}
+              />
+              <span>Preview Options</span>
+            </Button>
+            <Collapse in={previewOptionsOpen}>
+              <div>
+                <Form.Group id="transcode-size">
+                  <h6>Preview encoding preset</h6>
+                  <Form.Control
+                    className="w-auto input-control"
+                    as="select"
+                    value={previewPreset}
+                    onChange={(e: React.ChangeEvent<HTMLSelectElement>) =>
+                      setPreviewPreset(e.currentTarget.value)
+                    }
+                  >
+                    {Object.keys(GQL.PreviewPreset).map((p) => (
+                      <option value={p.toLowerCase()} key={p}>
+                        {p}
+                      </option>
+                    ))}
+                  </Form.Control>
+                  <Form.Text className="text-muted">
+                    The preset regulates size, quality and encoding time of
+                    preview generation. Presets beyond “slow” have diminishing
+                    returns and are not recommended.
+                  </Form.Text>
+                </Form.Group>
+
+                <Form.Group id="preview-segments">
+                  <h6>Number of segments in preview</h6>
+                  <Form.Control
+                    className="col col-sm-6 text-input"
+                    type="number"
+                    value={previewSegments.toString()}
+                    onInput={(e: React.FormEvent<HTMLInputElement>) =>
+                      setPreviewSegments(
+                        Number.parseInt(e.currentTarget.value, 10)
+                      )
+                    }
+                  />
+                  <Form.Text className="text-muted">
+                    Number of segments in preview files.
+                  </Form.Text>
+                </Form.Group>
+
+                <Form.Group id="preview-segment-duration">
+                  <h6>Preview segment duration</h6>
+                  <Form.Control
+                    className="col col-sm-6 text-input"
+                    type="number"
+                    value={previewSegmentDuration.toString()}
+                    onInput={(e: React.FormEvent<HTMLInputElement>) =>
+                      setPreviewSegmentDuration(
+                        Number.parseFloat(e.currentTarget.value)
+                      )
+                    }
+                  />
+                  <Form.Text className="text-muted">
+                    Duration of each preview segment, in seconds.
+                  </Form.Text>
+                </Form.Group>
+
+                <Form.Group id="preview-exclude-start">
+                  <h6>Exclude start time</h6>
+                  <Form.Control
+                    className="col col-sm-6 text-input"
+                    defaultValue={previewExcludeStart}
+                    onChange={(e: React.ChangeEvent<HTMLInputElement>) =>
+                      setPreviewExcludeStart(e.currentTarget.value)
+                    }
+                  />
+                  <Form.Text className="text-muted">
+                    Exclude the first x seconds from scene previews. This can be
+                    a value in seconds, or a percentage (eg 2%) of the total
+                    scene duration.
+                  </Form.Text>
+                </Form.Group>
+
+                <Form.Group id="preview-exclude-start">
+                  <h6>Exclude end time</h6>
+                  <Form.Control
+                    className="col col-sm-6 text-input"
+                    defaultValue={previewExcludeEnd}
+                    onChange={(e: React.ChangeEvent<HTMLInputElement>) =>
+                      setPreviewExcludeEnd(e.currentTarget.value)
+                    }
+                  />
+                  <Form.Text className="text-muted">
+                    Exclude the last x seconds from scene previews. This can be
+                    a value in seconds, or a percentage (eg 2%) of the total
+                    scene duration.
+                  </Form.Text>
+                </Form.Group>
+              </div>
+            </Collapse>
+          </div>
           <Form.Check
             id="sprite-task"
             checked={sprites}

ui/v2.5/src/components/Settings/SettingsConfigurationPanel.tsx

@@ -17,6 +17,16 @@ export const SettingsConfigurationPanel: React.FC = () => {
     undefined
   );
   const [cachePath, setCachePath] = useState<string | undefined>(undefined);
+  const [previewSegments, setPreviewSegments] = useState<number>(0);
+  const [previewSegmentDuration, setPreviewSegmentDuration] = useState<number>(
+    0
+  );
+  const [previewExcludeStart, setPreviewExcludeStart] = useState<
+    string | undefined
+  >(undefined);
+  const [previewExcludeEnd, setPreviewExcludeEnd] = useState<
+    string | undefined
+  >(undefined);
   const [previewPreset, setPreviewPreset] = useState<string>(
     GQL.PreviewPreset.Slow
   );
@@ -45,6 +55,10 @@ export const SettingsConfigurationPanel: React.FC = () => {
     databasePath,
     generatedPath,
     cachePath,
+    previewSegments,
+    previewSegmentDuration,
+    previewExcludeStart,
+    previewExcludeEnd,
     previewPreset: (previewPreset as GQL.PreviewPreset) ?? undefined,
     maxTranscodeSize,
     maxStreamingTranscodeSize,
@@ -68,6 +82,10 @@ export const SettingsConfigurationPanel: React.FC = () => {
       setDatabasePath(conf.general.databasePath);
       setGeneratedPath(conf.general.generatedPath);
       setCachePath(conf.general.cachePath);
+      setPreviewSegments(conf.general.previewSegments);
+      setPreviewSegmentDuration(conf.general.previewSegmentDuration);
+      setPreviewExcludeStart(conf.general.previewExcludeStart);
+      setPreviewExcludeEnd(conf.general.previewExcludeEnd);
       setPreviewPreset(conf.general.previewPreset);
       setMaxTranscodeSize(conf.general.maxTranscodeSize ?? undefined);
       setMaxStreamingTranscodeSize(
@@ -273,28 +291,6 @@ export const SettingsConfigurationPanel: React.FC = () => {
 
       <Form.Group>
         <h4>Video</h4>
-        <Form.Group id="transcode-size">
-          <h6>Preview encoding preset</h6>
-          <Form.Control
-            className="w-auto input-control"
-            as="select"
-            value={previewPreset}
-            onChange={(e: React.ChangeEvent<HTMLSelectElement>) =>
-              setPreviewPreset(e.currentTarget.value)
-            }
-          >
-            {Object.keys(GQL.PreviewPreset).map((p) => (
-              <option value={p.toLowerCase()} key={p}>
-                {p}
-              </option>
-            ))}
-          </Form.Control>
-          <Form.Text className="text-muted">
-            The preset regulates size, quality and encoding time of preview
-            generation. Presets beyond “slow” have diminishing returns and are
-            not recommended.
-          </Form.Text>
-        </Form.Group>
         <Form.Group id="transcode-size">
           <h6>Maximum transcode size</h6>
           <Form.Control
@@ -341,6 +337,94 @@ export const SettingsConfigurationPanel: React.FC = () => {
 
       <hr />
 
+      <Form.Group>
+        <h4>Preview Generation</h4>
+
+        <Form.Group id="transcode-size">
+          <h6>Preview encoding preset</h6>
+          <Form.Control
+            className="w-auto input-control"
+            as="select"
+            value={previewPreset}
+            onChange={(e: React.ChangeEvent<HTMLSelectElement>) =>
+              setPreviewPreset(e.currentTarget.value)
+            }
+          >
+            {Object.keys(GQL.PreviewPreset).map((p) => (
+              <option value={p.toLowerCase()} key={p}>
+                {p}
+              </option>
+            ))}
+          </Form.Control>
+          <Form.Text className="text-muted">
+            The preset regulates size, quality and encoding time of preview
+            generation. Presets beyond “slow” have diminishing returns and are
+            not recommended.
+          </Form.Text>
+        </Form.Group>
+        <Form.Group id="preview-segments">
+          <h6>Number of segments in preview</h6>
+          <Form.Control
+            className="col col-sm-6 text-input"
+            type="number"
+            value={previewSegments.toString()}
+            onInput={(e: React.FormEvent<HTMLInputElement>) =>
+              setPreviewSegments(Number.parseInt(e.currentTarget.value, 10))
+            }
+          />
+          <Form.Text className="text-muted">
+            Number of segments in preview files.
+          </Form.Text>
+        </Form.Group>
+
+        <Form.Group id="preview-segment-duration">
+          <h6>Preview segment duration</h6>
+          <Form.Control
+            className="col col-sm-6 text-input"
+            type="number"
+            value={previewSegmentDuration.toString()}
+            onInput={(e: React.FormEvent<HTMLInputElement>) =>
+              setPreviewSegmentDuration(
+                Number.parseFloat(e.currentTarget.value)
+              )
+            }
+          />
+          <Form.Text className="text-muted">
+            Duration of each preview segment, in seconds.
+          </Form.Text>
+        </Form.Group>
+
+        <Form.Group id="preview-exclude-start">
+          <h6>Exclude start time</h6>
+          <Form.Control
+            className="col col-sm-6 text-input"
+            defaultValue={previewExcludeStart}
+            onChange={(e: React.ChangeEvent<HTMLInputElement>) =>
+              setPreviewExcludeStart(e.currentTarget.value)
+            }
+          />
+          <Form.Text className="text-muted">
+            Exclude the first x seconds from scene previews. This can be a value
+            in seconds, or a percentage (eg 2%) of the total scene duration.
+          </Form.Text>
+        </Form.Group>
+
+        <Form.Group id="preview-exclude-start">
+          <h6>Exclude end time</h6>
+          <Form.Control
+            className="col col-sm-6 text-input"
+            defaultValue={previewExcludeEnd}
+            onChange={(e: React.ChangeEvent<HTMLInputElement>) =>
+              setPreviewExcludeEnd(e.currentTarget.value)
+            }
+          />
+          <Form.Text className="text-muted">
+            Exclude the last x seconds from scene previews. This can be a value
+            in seconds, or a percentage (eg 2%) of the total scene duration.
+          </Form.Text>
+        </Form.Group>
+      </Form.Group>
+
       <Form.Group id="generated-path">
         <h6>Scraping</h6>
         <Form.Control

ui/v2.5/src/index.scss

@@ -577,3 +577,9 @@ div.dropdown-menu {
     }
   }
 }
+
+.no-focus:focus {
+  background-color: inherit;
+  border-color: inherit;
+  box-shadow: inherit;
+}