From 53adafbc40329442fd16121d457b56a0742111c9 Mon Sep 17 00:00:00 2001
From: Esa Kataja <ekataja@gmail.com>
Date: Sat, 4 Apr 2026 18:08:25 +0300
Subject: [PATCH] add: add interlaced detection and bwdif deinterlacing

---
 cmd/videnc/main.go          |  4 ++--
 internal/encoder/encoder.go | 24 ++++++++++++++++--------
 2 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/cmd/videnc/main.go b/cmd/videnc/main.go
index 416765a..a9e5963 100644
--- a/cmd/videnc/main.go
+++ b/cmd/videnc/main.go
@@ -82,7 +82,7 @@ func processFile(inputPath string, cfg *types.Config, enc *encoder.Encoder, meta
 	filename := filepath.Base(inputPath)
 	isSeries, imdbID, tvmazeID, season, episode := metadata.ParseFilename(filename)
 
-	width, height, err := enc.GetMediaInfo(inputPath)
+	width, height, interlaced, err := enc.GetMediaInfo(inputPath)
 	if err != nil {
 		log.ErrorFile(inputPath, "Getting media info", err.Error())
 		mover.MoveToFailed(inputPath, cfg.Paths.Failed)
@@ -128,7 +128,7 @@ func processFile(inputPath string, cfg *types.Config, enc *encoder.Encoder, meta
 		DeleteOrigin: deleteOrigin,
 	}
 
-	if err := enc.Transcode(inputPath, job, meta); err != nil {
+	if err := enc.Transcode(inputPath, job, meta, interlaced); err != nil {
 		log.ErrorFile(inputPath, "Transcoding", err.Error())
 		mover.MoveToFailed(inputPath, cfg.Paths.Failed)
 		outputPath := filepath.Join(filepath.Dir(inputPath), "output.mkv")
diff --git a/internal/encoder/encoder.go b/internal/encoder/encoder.go
index d3f92e8..434e23f 100644
--- a/internal/encoder/encoder.go
+++ b/internal/encoder/encoder.go
@@ -33,21 +33,24 @@ func (e *Encoder) CheckDeps() error {
 	return nil
 }
 
-func (e *Encoder) GetMediaInfo(path string) (width, height int, err error) {
-	cmd := exec.Command(e.ffmpegPath, "-i", path, "-hide_banner")
+func (e *Encoder) GetMediaInfo(path string) (width, height int, interlaced bool, err error) {
+	cmd := exec.Command(e.ffmpegPath, "-i", path, "-hide_banner", "-vf", "idet")
 	output, _ := cmd.StderrPipe()
 	cmd.Start()
 
-	buf := make([]byte, 8192)
+	buf := make([]byte, 16384)
 	n, _ := output.Read(buf)
 	output.Close()
 
 	var w, h int
 	fmt.Sscanf(string(buf[:n]), "%dx%d", &w, &h)
-	return w, h, nil
+
+	interlaced = strings.Contains(string(buf[:n]), "TFF") || strings.Contains(string(buf[:n]), "BFF")
+
+	return w, h, interlaced, nil
 }
 
-func (e *Encoder) Transcode(input string, job *types.Job, metadata *types.Metadata) error {
+func (e *Encoder) Transcode(input string, job *types.Job, metadata *types.Metadata, interlaced bool) error {
 	dir := filepath.Dir(input)
 	audioWavs, err := e.extractAudio(input, dir)
 	if err != nil {
@@ -61,7 +64,7 @@ func (e *Encoder) Transcode(input string, job *types.Job, metadata *types.Metada
 	}
 	defer e.cleanupOpus(opusFiles)
 
-	if err := e.encodeVideo(input, opusFiles, job, metadata); err != nil {
+	if err := e.encodeVideo(input, opusFiles, job, metadata, interlaced); err != nil {
 		return fmt.Errorf("encoding video: %w", err)
 	}
 
@@ -93,12 +96,17 @@ func (e *Encoder) encodeOpus(wavs []string, dir string) ([]string, error) {
 	return opusFiles, nil
 }
 
-func (e *Encoder) encodeVideo(input string, opusFiles []string, job *types.Job, metadata *types.Metadata) error {
+func (e *Encoder) encodeVideo(input string, opusFiles []string, job *types.Job, metadata *types.Metadata, interlaced bool) error {
 	dir := filepath.Dir(input)
 	outFile := filepath.Join(dir, "output.mkv")
 
 	svtParams := fmt.Sprintf("film-grain=10:film-grain-denoise=1:scd=1:qm-min=4:qm-max=15:preset=%d", job.Preset)
 
+	vf := "zscale=filter=spline36:mode=16:9"
+	if interlaced {
+		vf = "bwdif=mode=0:par=-1:-1," + vf
+	}
+
 	args := []string{
 		"-y",
 		"-i", input,
@@ -106,7 +114,7 @@ func (e *Encoder) encodeVideo(input string, opusFiles []string, job *types.Job,
 		"-crf", strconv.Itoa(job.CRF),
 		"-svtav1-params", svtParams,
 		"-pix_fmt", "yuv420p10le",
-		"-vf", "zscale=filter=spline36:mode=16:9",
+		"-vf", vf,
 		"-c:a", "copy",
 		"-c:s", "copy",
 	}