chunker ui redo

core/chunker/chunker.py

@@ -28,7 +28,13 @@ class Chunker:
         chunk_duration: Duration of each chunk in seconds (default: 10.0)
     """
 
-    def __init__(self, file_path: str, chunk_duration: float = 10.0):
+    def __init__(
+        self,
+        file_path: str,
+        chunk_duration: float = 10.0,
+        start_time: float | None = None,
+        end_time: float | None = None,
+    ):
         if not os.path.isfile(file_path):
             raise ChunkReadError(f"File not found: {file_path}")
         if chunk_duration <= 0:
@@ -37,7 +43,16 @@ class Chunker:
         self.file_path = file_path
         self.chunk_duration = chunk_duration
         self.file_size = os.path.getsize(file_path)
-        self.source_duration = self._probe_duration()
+        full_duration = self._probe_duration()
+
+        # Apply time range
+        self.range_start = max(start_time or 0.0, 0.0)
+        self.range_end = min(end_time or full_duration, full_duration)
+        if self.range_start >= self.range_end:
+            raise ValueError(
+                f"Invalid range: start={self.range_start} >= end={self.range_end}"
+            )
+        self.source_duration = self.range_end - self.range_start
 
     def _probe_duration(self) -> float:
         """Get source file duration via FFmpeg probe."""
@@ -71,9 +86,9 @@ class Chunker:
         """
         total = self.expected_chunks
         for sequence in range(total):
-            start_time = sequence * self.chunk_duration
+            start_time = self.range_start + sequence * self.chunk_duration
             end_time = min(
-                start_time + self.chunk_duration, self.source_duration
+                start_time + self.chunk_duration, self.range_end
             )
             duration = end_time - start_time