优化转码逻辑

internal/service/service_builder.go

@@ -123,6 +123,7 @@ func (b *serviceContainerBuilder) initContentServices() {
 	b.c.Danmaku.SetStrmResolver(b.c.Strm.ResolvePlay)
 	// STRM 直连失败后的 HLS 转码：把 .strm 解析成 ffmpeg 可读取的本地路径或 HTTP 直链。
 	b.c.Transcoder.SetStrmPlayTargetResolver(b.c.Strm.ResolvePlayTarget)
+	b.c.Transcoder.SetProbe(b.c.FFprobe)
 	// 弹幕识别需要把远程 Emby 条目解析为 Media 元数据及可拉取前 16MB 的直链 URL。
 	if b.c.EmbyRemote != nil {
 		b.c.Danmaku.SetRemoteMediaResolver(func(ctx context.Context, encodedID string) (*model.Media, string, error) {

internal/service/stream_hls.go

@@ -6,19 +6,25 @@ import (
 	"net/http"
 	"os"
 	"path/filepath"
+	"strconv"
 	"strings"
 	"time"
 )
 
 // ServeHLSPlaylist makes sure a transcode is running and writes the m3u8.
 // We block (with a 30s timeout) until the playlist file shows up.
+//
+// Optional query `start` (seconds) restarts ffmpeg from that source offset so
+// the web player can scrub the full timeline without waiting for a full
+// head-to-tail transcode.
 func (s *StreamService) ServeHLSPlaylist(w http.ResponseWriter, r *http.Request, mediaID string) error {
 	// 「客户端直连解码」模式下宿主机不提供转码，HLS 一律拒绝，
 	// 迫使播放器走 direct play 本地解码。
 	if s.directPlayOnly(r.Context()) {
 		return ErrTranscodeDisabled
 	}
-	if _, err := s.transcoder.EnsureJob(r.Context(), mediaID); err != nil {
+	startSec := parseHLSStartSec(r)
+	if _, err := s.transcoder.EnsureJobFrom(r.Context(), mediaID, startSec); err != nil {
 		return err
 	}
 	s.transcoder.TouchJob(mediaID)
@@ -48,10 +54,31 @@ func (s *StreamService) ServeHLSPlaylist(w http.ResponseWriter, r *http.Request,
 	return nil
 }
 
+func parseHLSStartSec(r *http.Request) float64 {
+	if r == nil {
+		return 0
+	}
+	raw := strings.TrimSpace(r.URL.Query().Get("start"))
+	if raw == "" {
+		return 0
+	}
+	v, err := strconv.ParseFloat(raw, 64)
+	if err != nil || v < 0 {
+		return 0
+	}
+	return v
+}
+
 func appendQueryToHLSSegments(playlist, rawQuery string) string {
 	if strings.TrimSpace(rawQuery) == "" {
 		return playlist
 	}
+	// Segment fetches only need auth/profile tokens; drop start= so a seek
+	// restart does not keep forcing EnsureJobFrom on every .ts hit.
+	q := filterHLSSegmentQuery(rawQuery)
+	if q == "" {
+		return playlist
+	}
 	lines := strings.SplitAfter(playlist, "\n")
 	for i, line := range lines {
 		trimmed := strings.TrimSpace(line)
@@ -65,12 +92,31 @@ func appendQueryToHLSSegments(playlist, rawQuery string) string {
 			} else if strings.HasSuffix(line, "\n") {
 				lineEnding = "\n"
 			}
-			lines[i] = strings.TrimRight(line, "\r\n") + "?" + rawQuery + lineEnding
+			lines[i] = strings.TrimRight(line, "\r\n") + "?" + q + lineEnding
 		}
 	}
 	return strings.Join(lines, "")
 }
 
+func filterHLSSegmentQuery(rawQuery string) string {
+	parts := strings.Split(rawQuery, "&")
+	kept := make([]string, 0, len(parts))
+	for _, part := range parts {
+		if part == "" {
+			continue
+		}
+		key := part
+		if i := strings.IndexByte(part, '='); i >= 0 {
+			key = part[:i]
+		}
+		if strings.EqualFold(key, "start") {
+			continue
+		}
+		kept = append(kept, part)
+	}
+	return strings.Join(kept, "&")
+}
+
 // ServeHLSSegment writes a single .ts segment from the on-disk cache.
 func (s *StreamService) ServeHLSSegment(w http.ResponseWriter, r *http.Request, mediaID, segment string) error {
 	s.transcoder.TouchJob(mediaID)

internal/service/transcoder.go

@@ -50,6 +50,7 @@ type TranscoderService struct {
 	mu          sync.Mutex
 	jobs        map[string]*hlsJob
 	strmResolve func(ctx context.Context, raw string) (*StrmPlayResult, error)
+	probe       *FFprobeService
 }
 
 // hlsJob holds the live state of one ffmpeg run.
@@ -61,6 +62,9 @@ type hlsJob struct {
 	lastAccess time.Time
 	playlistOK bool
 	encoder    string
+	// startSec is the source seek offset fed to ffmpeg (-ss). The HLS
+	// playlist itself always starts at t=0 for that session.
+	startSec float64
 }
 
 var (
@@ -92,13 +96,24 @@ func (t *TranscoderService) PlaylistPath(mediaID string) string {
 	return filepath.Join(t.HLSDir(mediaID), "index.m3u8")
 }
 
-// EnsureJob makes sure a transcode is running for mediaID. The function is
-// non-blocking: it returns the playlist path immediately. The caller is
-// expected to poll until WaitReady reports true.
+// EnsureJob makes sure a transcode is running for mediaID from the start of
+// the source. Prefer EnsureJobFrom when the player seeks into the middle.
 func (t *TranscoderService) EnsureJob(ctx context.Context, mediaID string) (string, error) {
+	return t.EnsureJobFrom(ctx, mediaID, 0)
+}
+
+// EnsureJobFrom starts (or reuses) an HLS job that seeks the source to
+// startSec before encoding. Reusing only happens when an active job already
+// matches that offset; otherwise the previous job is cancelled and the HLS
+// cache dir is wiped so the player can jump without waiting for a full
+// head-to-tail transcode.
+func (t *TranscoderService) EnsureJobFrom(ctx context.Context, mediaID string, startSec float64) (string, error) {
 	if !t.cfg.Transcoder.Enabled {
 		return "", ErrTranscodeDisabled
 	}
+	if startSec < 0 {
+		startSec = 0
+	}
 	m, err := t.repo.Media.FindByID(ctx, mediaID)
 	if err != nil {
 		return "", err
@@ -106,11 +121,16 @@ func (t *TranscoderService) EnsureJob(ctx context.Context, mediaID string) (stri
 	if m == nil {
 		return "", ErrMediaNotFound
 	}
+
 	t.mu.Lock()
-	if _, ok := t.jobs[mediaID]; ok {
-		t.touchJobLocked(mediaID)
-		t.mu.Unlock()
-		return t.PlaylistPath(mediaID), nil
+	if existing, ok := t.jobs[mediaID]; ok {
+		if sameHLSStart(existing.startSec, startSec) {
+			t.touchJobLocked(mediaID)
+			t.mu.Unlock()
+			return t.PlaylistPath(mediaID), nil
+		}
+		existing.cancel()
+		delete(t.jobs, mediaID)
 	}
 	t.mu.Unlock()
 
@@ -118,27 +138,34 @@ func (t *TranscoderService) EnsureJob(ctx context.Context, mediaID string) (stri
 	if err != nil {
 		return "", err
 	}
+	input.StartSec = startSec
+	t.maybeFillDuration(ctx, m, input)
 	if _, err := t.resolveFFmpegPath(); err != nil {
 		return "", err
 	}
 
+	outDir := t.HLSDir(mediaID)
+	// Wipe prior segments so a mid-file restart cannot serve stale early chunks.
+	_ = os.RemoveAll(outDir)
+	if err := os.MkdirAll(outDir, 0o750); err != nil {
+		return "", err
+	}
+
 	t.mu.Lock()
-	if _, ok := t.jobs[mediaID]; ok {
-		t.touchJobLocked(mediaID)
-		t.mu.Unlock()
-		return t.PlaylistPath(mediaID), nil
+	if existing, ok := t.jobs[mediaID]; ok {
+		if sameHLSStart(existing.startSec, startSec) {
+			t.touchJobLocked(mediaID)
+			t.mu.Unlock()
+			return t.PlaylistPath(mediaID), nil
+		}
+		existing.cancel()
+		delete(t.jobs, mediaID)
 	}
 	if max := t.maxConcurrent(); max > 0 && len(t.jobs) >= max {
 		t.mu.Unlock()
 		return "", ErrTranscodeBusy
 	}
 
-	outDir := t.HLSDir(mediaID)
-	if err := os.MkdirAll(outDir, 0o750); err != nil {
-		t.mu.Unlock()
-		return "", err
-	}
-
 	jobCtx, cancel := context.WithCancel(context.Background())
 	job := &hlsJob{
 		mediaID:    mediaID,
@@ -147,6 +174,7 @@ func (t *TranscoderService) EnsureJob(ctx context.Context, mediaID string) (stri
 		startedAt:  time.Now(),
 		lastAccess: time.Now(),
 		encoder:    t.effectiveEncoder(),
+		startSec:   startSec,
 	}
 	t.jobs[mediaID] = job
 	t.mu.Unlock()
@@ -156,6 +184,14 @@ func (t *TranscoderService) EnsureJob(ctx context.Context, mediaID string) (stri
 	return t.PlaylistPath(mediaID), nil
 }
 
+func sameHLSStart(a, b float64) bool {
+	const tol = 0.75
+	if a < b {
+		return b-a < tol
+	}
+	return a-b < tol
+}
+
 // SetStrmPlayTargetResolver wires STRM URL resolution so ffmpeg can transcode
 // remote .strm media (HTTP 直链 or local source path) after direct play fails.
 func (t *TranscoderService) SetStrmPlayTargetResolver(resolve func(ctx context.Context, raw string) (*StrmPlayResult, error)) {
@@ -165,6 +201,40 @@ func (t *TranscoderService) SetStrmPlayTargetResolver(resolve func(ctx context.C
 	t.strmResolve = resolve
 }
 
+// SetProbe wires ffprobe so STRM/HLS jobs can persist source duration when the
+// media row still has duration_sec=0 (common for .strm that was never probed).
+func (t *TranscoderService) SetProbe(probe *FFprobeService) {
+	if t == nil {
+		return
+	}
+	t.probe = probe
+}
+
+func (t *TranscoderService) maybeFillDuration(ctx context.Context, m *model.Media, input transcodeInput) {
+	if t == nil || t.probe == nil || m == nil || m.DurationSec > 0 || strings.TrimSpace(input.Source) == "" {
+		return
+	}
+	var (
+		res *ProbeResult
+		err error
+	)
+	if isHTTPSource(input.Source) {
+		res, err = t.probe.ProbeHTTP(ctx, input.Source, input.Headers)
+	} else {
+		res, err = t.probe.Probe(ctx, input.Source)
+	}
+	if err != nil || res == nil || res.DurationSec <= 0 {
+		return
+	}
+	m.DurationSec = res.DurationSec
+	if t.repo == nil || t.repo.DB == nil {
+		return
+	}
+	if err := t.repo.DB.WithContext(ctx).Model(&model.Media{}).Where("id = ?", m.ID).Update("duration_sec", res.DurationSec).Error; err != nil && t.log != nil {
+		t.log.Debug("persist probed duration failed", zap.String("media_id", m.ID), zap.Error(err))
+	}
+}
+
 func (t *TranscoderService) resolveTranscodeInput(ctx context.Context, m *model.Media) (transcodeInput, error) {
 	if m == nil {
 		return transcodeInput{}, ErrMediaNotFound

internal/service/transcoder_ffmpeg_args.go

@@ -11,8 +11,9 @@ import (
 )
 
 type transcodeInput struct {
-	Source  string
-	Headers map[string]string
+	Source   string
+	Headers  map[string]string
+	StartSec float64
 }
 
 type ffmpegArgSettings struct {
@@ -125,6 +126,11 @@ func baseFFmpegArgs(preInput string, realtime bool) []string {
 
 func appendInputAndVideoArgs(args []string, input transcodeInput, settings ffmpegArgSettings, video ffmpegVideoPlan) []string {
 	args = append(args, ffmpegHTTPInputArgs(input)...)
+	// Input seek (-ss before -i) lets mid-file HLS restarts jump without
+	// decoding everything before the click position.
+	if input.StartSec > 0.05 {
+		args = append(args, "-ss", strconv.FormatFloat(input.StartSec, 'f', 3, 64))
+	}
 	args = append(args, "-i", input.Source, "-map", "0:v:0?", "-map", "0:a:0?", "-vf", video.filter, "-c:v", video.codec)
 	if settings.threads > 0 && video.codec == "libx264" {
 		args = append(args, "-threads", strconv.Itoa(settings.threads))

internal/service/transcoder_ffmpeg_probe.go

@@ -40,6 +40,7 @@ func (t *TranscoderService) runFFmpeg(ctx context.Context, job *hlsJob, input tr
 		zap.String("media_id", job.mediaID),
 		zap.String("encoder", job.encoder),
 		zap.String("source", input.Source),
+		zap.Float64("start_sec", input.StartSec),
 	)
 	t.hub.Publish("transcode", map[string]any{
 		"media_id": job.mediaID,

internal/service/transcoder_test.go

@@ -193,3 +193,47 @@ func TestBuildFFmpegArgsHTTPInputReconnect(t *testing.T) {
 		t.Fatalf("http flags must come before -i, args=%v", args)
 	}
 }
+
+func TestBuildFFmpegArgsInputSeekBeforeDashI(t *testing.T) {
+	cfg := &config.Config{}
+	cfg.Transcoder.MaxHeight = 720
+	cfg.Transcoder.SegmentSeconds = 4
+	args := buildFFmpegArgsForInput(cfg, transcodeInput{
+		Source:   "/x.mkv",
+		StartSec: 125.5,
+	}, "/o/x.m3u8", "/o/seg_%05d.ts")
+	idxSS, idxI := -1, -1
+	for i, arg := range args {
+		if arg == "-ss" {
+			idxSS = i
+		}
+		if arg == "-i" && idxI < 0 {
+			idxI = i
+		}
+	}
+	if idxSS < 0 || idxI < 0 || idxSS > idxI {
+		t.Fatalf("expected -ss before -i, args=%v", args)
+	}
+	if args[idxSS+1] != "125.500" {
+		t.Fatalf("start = %q", args[idxSS+1])
+	}
+}
+
+func TestSameHLSStart(t *testing.T) {
+	if !sameHLSStart(10, 10.2) {
+		t.Fatal("expected close starts to match")
+	}
+	if sameHLSStart(10, 12) {
+		t.Fatal("expected distant starts to differ")
+	}
+}
+
+func TestFilterHLSSegmentQueryDropsStart(t *testing.T) {
+	got := filterHLSSegmentQuery("token=abc&start=120.5&profile_id=1")
+	if strings.Contains(got, "start=") {
+		t.Fatalf("start should be stripped, got %q", got)
+	}
+	if !strings.Contains(got, "token=abc") || !strings.Contains(got, "profile_id=1") {
+		t.Fatalf("auth/profile query should remain, got %q", got)
+	}
+}