456 lines
9.5 KiB
Go
456 lines
9.5 KiB
Go
// backend\preview_teaser.go
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package main
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import (
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"bufio"
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"bytes"
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"context"
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"fmt"
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"math"
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"os"
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"os/exec"
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"strconv"
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"strings"
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"time"
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)
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// Minimale Segmentdauer, damit ffmpeg nicht mit zu kurzen Schnipseln zickt.
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const minSegmentDuration = 0.75 // Sekunden
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const defaultTeaserSegments = 12
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type TeaserPreviewOptions struct {
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Segments int
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SegmentDuration float64
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Width int
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Preset string
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CRF int
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// wird von uns "hart" auf true gesetzt (Audio ist NICHT optional)
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Audio bool
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AudioBitrate string
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UseVsync2 bool
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}
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// stepSizeAndOffset verteilt die Startpunkte über das Video.
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// Rückgabe: stepSize, offset (beide in Sekunden).
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func (o TeaserPreviewOptions) stepSizeAndOffset(dur float64) (float64, float64) {
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if dur <= 0 {
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return 0, 0
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}
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n := o.Segments
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if n < 1 {
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n = 1
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}
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segDur := o.SegmentDuration
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if segDur <= 0 {
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segDur = 1
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}
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if segDur < minSegmentDuration {
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segDur = minSegmentDuration
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}
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// letzter sinnvoller Start (kleiner Sicherheitsabstand)
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maxStart := dur - 0.05 - segDur
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if maxStart < 0 {
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maxStart = 0
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}
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// 1 Segment -> Mitte
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if n == 1 {
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return 0, maxStart * 0.5
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}
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// kleine Ränder, damit nicht immer ganz am Anfang/Ende
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margin := 0.05 * maxStart
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if margin < 0 {
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margin = 0
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}
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span := maxStart - 2*margin
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if span < 0 {
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span = maxStart
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margin = 0
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}
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step := 0.0
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if n > 1 {
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step = span / float64(n-1)
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}
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return step, margin
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}
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func generateTeaserClipsMP4(ctx context.Context, srcPath, outPath string, clipLenSec float64, maxClips int) error {
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return generateTeaserClipsMP4WithProgress(ctx, srcPath, outPath, clipLenSec, maxClips, nil)
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}
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func generateTeaserClipsMP4WithProgress(
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ctx context.Context,
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srcPath, outPath string,
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clipLenSec float64,
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maxClips int,
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onRatio func(r float64),
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) error {
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// kompatible Defaults aus deiner Signatur -> Options
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opts := TeaserPreviewOptions{
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Segments: maxClips,
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SegmentDuration: clipLenSec,
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// stash-like Defaults
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Width: 640,
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Preset: "veryfast",
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CRF: 21,
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Audio: true,
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AudioBitrate: "128k",
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UseVsync2: false,
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}
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return generateTeaserPreviewMP4WithProgress(ctx, srcPath, outPath, opts, onRatio)
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}
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func generateTeaserChunkMP4(ctx context.Context, src, out string, start, dur float64, opts TeaserPreviewOptions) error {
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// ✅ Audio ist Pflicht (nicht optional)
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opts.Audio = true
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tmp := strings.TrimSuffix(out, ".mp4") + ".part.mp4"
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segDur := dur
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if segDur < minSegmentDuration {
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segDur = minSegmentDuration
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}
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args := []string{
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"-y", "-hide_banner", "-loglevel", "error",
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}
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args = append(args, ffmpegInputTol...)
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args = append(args,
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"-ss", fmt.Sprintf("%.3f", start),
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"-t", fmt.Sprintf("%.3f", segDur),
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"-i", src,
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"-map", "0:v:0",
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"-c:v", "libx264",
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"-pix_fmt", "yuv420p",
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"-profile:v", "high",
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"-level", "4.2",
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"-preset", opts.Preset,
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"-crf", strconv.Itoa(opts.CRF),
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"-threads", "4",
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)
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if opts.UseVsync2 {
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args = append(args, "-vsync", "2")
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}
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if opts.Audio {
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args = append(args,
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"-map", "0:a:0", // Audio Pflicht
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"-c:a", "aac",
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"-b:a", opts.AudioBitrate,
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"-ac", "2",
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"-shortest",
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)
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} else {
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args = append(args, "-an")
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}
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args = append(args, "-movflags", "+faststart", tmp)
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cmd := exec.CommandContext(ctx, ffmpegPath, args...)
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var stderr bytes.Buffer
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cmd.Stderr = &stderr
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if err := cmd.Run(); err != nil {
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_ = os.Remove(tmp)
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return fmt.Errorf("ffmpeg teaser chunk failed: %v (%s)", err, strings.TrimSpace(stderr.String()))
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}
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_ = os.Remove(out)
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return os.Rename(tmp, out)
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}
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func computeTeaserStarts(dur float64, opts TeaserPreviewOptions) (starts []float64, segDur float64, usedSegments int) {
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// opts normalisieren wie in generateTeaserPreviewMP4WithProgress
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if opts.SegmentDuration <= 0 {
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opts.SegmentDuration = 1
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}
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if opts.Segments <= 0 {
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opts.Segments = defaultTeaserSegments
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}
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segDur = opts.SegmentDuration
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if segDur < minSegmentDuration {
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segDur = minSegmentDuration
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}
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// Kurzvideo-Fallback: wenn Video kürzer als Segments*SegmentDuration -> 1 Segment über ganze Dauer
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if dur > 0 && dur < segDur*float64(opts.Segments) {
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opts.Segments = 1
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segDur = dur
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}
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usedSegments = opts.Segments
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// Dauer unbekannt: Start 0
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if !(dur > 0) {
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return []float64{0}, segDur, 1
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}
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stepSize, offset := opts.stepSizeAndOffset(dur)
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starts = make([]float64, 0, opts.Segments)
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for i := 0; i < opts.Segments; i++ {
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t := offset + float64(i)*stepSize
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maxStart := math.Max(0, dur-0.05-segDur)
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if t < 0 {
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t = 0
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}
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if t > maxStart {
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t = maxStart
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}
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if t < 0.05 {
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t = 0.05
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}
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starts = append(starts, t)
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}
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return starts, segDur, usedSegments
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}
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func generateTeaserPreviewMP4WithProgress(
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ctx context.Context,
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srcPath, outPath string,
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opts TeaserPreviewOptions,
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onRatio func(r float64),
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) error {
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// ✅ Audio ist Pflicht (nicht optional)
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opts.Audio = true
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// Defaults
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if opts.SegmentDuration <= 0 {
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opts.SegmentDuration = 1
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}
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if opts.Segments <= 0 {
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opts.Segments = defaultTeaserSegments
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}
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if opts.Width <= 0 {
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opts.Width = 640
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}
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if opts.Preset == "" {
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opts.Preset = "veryfast"
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}
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if opts.CRF <= 0 {
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opts.CRF = 21
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}
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if opts.AudioBitrate == "" {
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opts.AudioBitrate = "128k"
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}
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segDur := opts.SegmentDuration
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if segDur < minSegmentDuration {
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segDur = minSegmentDuration
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}
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// Dauer holen (einmalig; wird gecached)
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dur, _ := durationSecondsCached(ctx, srcPath)
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// Kurzvideo-Fallback wie "die andere":
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// Wenn Video kürzer als Segments*SegmentDuration -> Single Preview über komplette Dauer
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if dur > 0 && dur < segDur*float64(opts.Segments) {
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// als 1 Segment behandeln, Duration = dur
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opts.Segments = 1
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segDur = dur
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}
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// Wenn Dauer unbekannt/zu klein: ab 0 ein Stück
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if !(dur > 0) {
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if onRatio != nil {
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onRatio(0)
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}
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// hier könntest du auch segDur verwenden; ich nehme min(8, segDur) ähnlich wie vorher
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err := generateTeaserChunkMP4(ctx, srcPath, outPath, 0, math.Min(8, segDur), opts)
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if onRatio != nil {
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onRatio(1)
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}
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return err
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}
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starts, segDurComputed, _ := computeTeaserStarts(dur, opts)
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// segDur ist später im Code benutzt -> segDur damit überschreiben:
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segDur = segDurComputed
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expectedOutSec := float64(len(starts)) * segDur
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tmp := strings.TrimSuffix(outPath, ".mp4") + ".part.mp4"
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args := []string{
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"-y",
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"-nostats",
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"-progress", "pipe:1",
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"-hide_banner",
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"-loglevel", "error",
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}
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// Inputs: pro Segment eigener -ss/-t/-i (wie bei dir)
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for _, t := range starts {
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args = append(args, ffmpegInputTol...)
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args = append(args,
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"-ss", fmt.Sprintf("%.3f", t),
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"-t", fmt.Sprintf("%.3f", segDur),
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"-i", srcPath,
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)
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}
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// filter_complex bauen
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var fc strings.Builder
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for i := range starts {
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// stash-like: ScaleWidth(640), pix_fmt yuv420p, profile high/level 4.2 später in output args
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fmt.Fprintf(&fc,
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"[%d:v]scale=%d:-2,setsar=1,setpts=PTS-STARTPTS[v%d];",
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i, opts.Width, i,
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)
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if opts.Audio {
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// dein “concat-safe” Audio normalisieren (gute Idee)
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fmt.Fprintf(&fc,
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"[%d:a]aresample=48000,aformat=channel_layouts=stereo,asetpts=PTS-STARTPTS[a%d];",
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i, i,
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)
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}
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}
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// interleaved concat inputs
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for i := range starts {
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if opts.Audio {
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fmt.Fprintf(&fc, "[v%d][a%d]", i, i)
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} else {
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fmt.Fprintf(&fc, "[v%d]", i)
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}
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}
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if opts.Audio {
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fmt.Fprintf(&fc, "concat=n=%d:v=1:a=1[v][a]", len(starts))
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} else {
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fmt.Fprintf(&fc, "concat=n=%d:v=1:a=0[v]", len(starts))
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}
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args = append(args, "-filter_complex", fc.String())
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// map outputs
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args = append(args, "-map", "[v]")
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if opts.Audio {
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args = append(args, "-map", "[a]")
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}
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// Video encode (stash-like)
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args = append(args,
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"-c:v", "libx264",
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"-pix_fmt", "yuv420p",
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"-profile:v", "high",
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"-level", "4.2",
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"-preset", opts.Preset,
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"-crf", strconv.Itoa(opts.CRF),
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"-threads", "4",
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)
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if opts.UseVsync2 {
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args = append(args, "-vsync", "2")
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}
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// Audio encode optional (stash-like 128k), plus dein -ac 2
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if opts.Audio {
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args = append(args,
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"-c:a", "aac",
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"-b:a", opts.AudioBitrate,
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"-ac", "2",
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"-shortest",
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)
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}
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args = append(args, "-movflags", "+faststart", tmp)
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cmd := exec.CommandContext(ctx, ffmpegPath, args...)
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stdout, err := cmd.StdoutPipe()
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if err != nil {
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return err
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}
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var stderr bytes.Buffer
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cmd.Stderr = &stderr
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if err := cmd.Start(); err != nil {
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return err
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}
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sc := bufio.NewScanner(stdout)
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sc.Buffer(make([]byte, 0, 64*1024), 1024*1024)
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var lastSent float64
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var lastAt time.Time
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send := func(outSec float64, force bool) {
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if onRatio == nil {
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return
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}
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if expectedOutSec > 0 && outSec > 0 {
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r := outSec / expectedOutSec
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if r < 0 {
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r = 0
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}
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if r > 1 {
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r = 1
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}
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if r-lastSent < 0.01 && !force {
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return
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}
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if !lastAt.IsZero() && time.Since(lastAt) < 150*time.Millisecond && !force {
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return
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}
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lastSent = r
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lastAt = time.Now()
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onRatio(r)
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return
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}
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if force {
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onRatio(1)
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}
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}
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var outSec float64
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for sc.Scan() {
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line := strings.TrimSpace(sc.Text())
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if line == "" {
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continue
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}
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parts := strings.SplitN(line, "=", 2)
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if len(parts) != 2 {
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continue
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}
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k, v := parts[0], parts[1]
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switch k {
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case "out_time_ms":
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if n, perr := strconv.ParseInt(strings.TrimSpace(v), 10, 64); perr == nil && n > 0 {
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outSec = float64(n) / 1_000_000.0
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send(outSec, false)
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}
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case "out_time":
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if s := parseFFmpegOutTime(v); s > 0 {
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outSec = s
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send(outSec, false)
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}
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case "progress":
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if strings.TrimSpace(v) == "end" {
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send(outSec, true)
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}
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}
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}
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if err := cmd.Wait(); err != nil {
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_ = os.Remove(tmp)
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return fmt.Errorf("ffmpeg teaser preview failed: %v (%s)", err, strings.TrimSpace(stderr.String()))
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}
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_ = os.Remove(outPath)
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return os.Rename(tmp, outPath)
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}
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