diff --git a/config.toml b/config.toml
index f539ef3..f828418 100644
--- a/config.toml
+++ b/config.toml
@@ -5,9 +5,6 @@
 # Input files — relative to repo root or absolute. Same as extract.py inputs.
 file_a = "/home/honney/Videos/Drachenzähmen/Drachenzaehmen.mp4"
 file_b = "/home/honney/Videos/Drachenzähmen/How to Train Your Dragon.mkv"
-# Output stem names (without extension). If omitted, derived from input filename.
-stem_a = "file_a"
-stem_b = "file_b"
 # Window to extract (seconds). This is the ONLY duration needed.
 duration = 30
 # Start offset in file (seconds, 0 = file start). ffmpeg -ss before -i for fast seek.
diff --git a/extract.py b/extract.py
index 14d96ab..803d81d 100644
--- a/extract.py
+++ b/extract.py
@@ -26,7 +26,6 @@ _cfg_target_lufs = -14
 _cfg_target_tp = -1.0
 _cfg_target_lra = 11
 _cfg_audio_stream = None  # None = prompt, int = index, "skip" = no audio extraction
-_cfg_stems = [None, None]  # stem_a, stem_b from config
 try:
     try:
         import tomllib  # py3.11+
@@ -72,10 +71,6 @@ try:
                 _cfg_audio_stream = "skip"
             elif isinstance(val, (int, float)):
                 _cfg_audio_stream = int(val)
-        if _ex.get("stem_a"):
-            _cfg_stems[0] = str(_ex["stem_a"])
-        if _ex.get("stem_b"):
-            _cfg_stems[1] = str(_ex["stem_b"])
         if _cfg_inputs:
             print(f"[config] loaded {CONFIG_PATH}: duration={_cfg_duration}s start={_cfg_start}s target_fps={_cfg_target_fps}")
 except Exception as _e:
@@ -383,14 +378,42 @@ if len(valid_fps) >= 2:
         elif not all_match:
             print(f"NOTE: inputs share fps {valid_fps[0]:.3f} but differ from target {TARGET_FPS} — both will be normalized to {TARGET_FPS}.")
 
+# ─── Derive output stems from path divergence ───
+def _derive_stems(paths: list[str]) -> list[str]:
+    """For each path, give a stem: if filenames differ, just use filename stem.
+    If filenames match, walk up dirs until parents diverge and use the remaining relative path."""
+    stems = []
+    # first strip extensions, get bare names
+    basenames = [os.path.splitext(os.path.basename(p))[0] for p in paths]
+    if len(paths) == 1 or basenames[0] != basenames[1]:
+        # different filenames — just use them directly
+        return basenames
+    # same filename — walk up until parent dirs differ
+    parts_a = os.path.normpath(paths[0]).split(os.sep)
+    parts_b = os.path.normpath(paths[1]).split(os.sep)
+    # find divergence point from the end (walk up from file)
+    common = 0
+    for a, b in zip(reversed(parts_a), reversed(parts_b)):
+        if a == b:
+            common += 1
+        else:
+            break
+    # remaining parts after divergence = relative unique path (dirs + filename)
+    rel_a = parts_a[len(parts_a) - common:]   # includes filename
+    rel_b = parts_b[len(parts_b) - common:]
+    stem_a = os.path.join(*rel_a) if len(rel_a) > 1 else rel_a[0]
+    stem_b = os.path.join(*rel_b) if len(rel_b) > 1 else rel_b[0]
+    return [stem_a, stem_b]
+
+_stems = _derive_stems(INPUT_FILES)
+
 # ─── Prepare output folder ───
 os.makedirs(OUT_DIR, exist_ok=True)
 
 for _file_idx, INPUT_FILE in enumerate(INPUT_FILES):
 
     # ─── Derive output filenames ───
-    cfg_stem = _cfg_stems[_file_idx] if _file_idx < len(_cfg_stems) else None
-    stem = cfg_stem if cfg_stem else os.path.splitext(os.path.basename(INPUT_FILE))[0]
+    stem = _stems[_file_idx]
     video_out = os.path.join(OUT_DIR, f"{stem}_video.mkv")  # FFV1
     audio_out = os.path.join(OUT_DIR, f"{stem}_audio.wav")  # PCM f32