From 1a43c4725d43c7532f3899caf778fc5e1cf41796 Mon Sep 17 00:00:00 2001
From: Ethanfel <ethan.fel@ts-pc.fr>
Date: Mon, 6 Apr 2026 13:51:02 +0200
Subject: [PATCH] feat: portrait crop filter in build_ffmpeg_command

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 main.py             | 36 +++++++++++++++++++++++++++++++++---
 tests/test_utils.py | 28 ++++++++++++++++++++++++++++
 2 files changed, 61 insertions(+), 3 deletions(-)

diff --git a/main.py b/main.py
index 8cf572c..edbfc1b 100644
--- a/main.py
+++ b/main.py
@@ -33,6 +33,8 @@ def format_time(seconds: float) -> str:
 def build_ffmpeg_command(
     input_path: str, start: float, output_path: str,
     short_side: int | None = None,
+    portrait_ratio: str | None = None,
+    crop_center: float = 0.5,
 ) -> list[str]:
     # -ss before -i: fast input-seeking. Safe here because we always re-encode
     # (libx264/aac), so there is no keyframe-alignment issue from pre-input seek.
@@ -42,16 +44,44 @@ def build_ffmpeg_command(
         "-i", input_path,
         "-t", "8",
     ]
+
+    filters: list[str] = []
+    if portrait_ratio is not None:
+        filters.append(_portrait_crop_filter(portrait_ratio, crop_center))
     if short_side is not None:
         # Scale so the shorter dimension equals short_side.
-        # if(lt(iw,ih),...) → portrait: fix width; landscape: fix height.
+        # if(lt(iw,ih),...) → portrait output: fix width; landscape: fix height.
         # -2 keeps aspect ratio with even-pixel rounding (libx264 requirement).
-        scale = f"scale='if(lt(iw,ih),{short_side},-2)':'if(lt(iw,ih),-2,{short_side})'"
-        cmd += ["-vf", scale]
+        filters.append(
+            f"scale='if(lt(iw,ih),{short_side},-2)':'if(lt(iw,ih),-2,{short_side})'"
+        )
+    if filters:
+        cmd += ["-vf", ",".join(filters)]
+
     cmd += ["-c:v", "libx264", "-c:a", "aac", output_path]
     return cmd
 
 
+_RATIOS: dict[str, tuple[int, int]] = {
+    "9:16": (9, 16),
+    "4:5":  (4, 5),
+    "1:1":  (1, 1),
+}
+
+
+def _portrait_crop_filter(ratio: str, crop_center: float) -> str:
+    """Return an ffmpeg crop= filter expression for the given portrait ratio.
+
+    Uses ffmpeg expression syntax so source dimensions are resolved at runtime.
+    Commas inside min()/max() are escaped with \\, to prevent ffmpeg's
+    filtergraph parser from treating them as filter-chain separators.
+    """
+    num, den = _RATIOS[ratio]
+    cw = f"ih*{num}/{den}"
+    x = f"max(0\\,min((iw-{cw})*{crop_center}\\,iw-{cw}))"
+    return f"crop={cw}:ih:{x}:0"
+
+
 def _normalize_filename(filename: str) -> str:
     """Strip extension and common resolution/quality tags for fuzzy comparison."""
     name = os.path.splitext(filename)[0].lower()
diff --git a/tests/test_utils.py b/tests/test_utils.py
index 3b283b8..c567798 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -145,3 +145,31 @@ def test_db_get_markers_no_match():
 def test_db_get_markers_disabled():
     db = ProcessedDB("/no/such/directory/8cut.db")
     assert db.get_markers("x.mp4") == []
+
+def test_ffmpeg_command_portrait_only():
+    cmd = build_ffmpeg_command(
+        "/in/video.mp4", 0.0, "/out/clip.mp4",
+        portrait_ratio="9:16", crop_center=0.5,
+    )
+    assert "-vf" in cmd
+    vf = cmd[cmd.index("-vf") + 1]
+    assert "crop" in vf
+    assert "9" in vf
+    assert "scale" not in vf
+    assert cmd[-1] == "/out/clip.mp4"
+
+def test_ffmpeg_command_portrait_and_resize():
+    cmd = build_ffmpeg_command(
+        "/in/video.mp4", 0.0, "/out/clip.mp4",
+        short_side=256, portrait_ratio="9:16", crop_center=0.5,
+    )
+    assert "-vf" in cmd
+    vf = cmd[cmd.index("-vf") + 1]
+    assert "crop" in vf
+    assert "scale" in vf
+    assert vf.index("crop") < vf.index("scale")
+    assert cmd[-1] == "/out/clip.mp4"
+
+def test_ffmpeg_command_portrait_off():
+    cmd = build_ffmpeg_command("/in/video.mp4", 0.0, "/out/clip.mp4")
+    assert "-vf" not in cmd