whisper: add directory transcription support

Add support for transcribing all files in a directory recursively.
The implementation lets ffmpeg handle file validation instead of
filtering by extension. Update README with minimal documentation
for directory support.

whisper/README.md

@@ -31,6 +31,11 @@ mlx_whisper audio_file.mp3
 
 This will make a text file `audio_file.txt` with the results.
 
+You can also transcribe a directory of audio files:
+```sh
+mlx_whisper path/to/directory/
+```
+
 Use `-f` to specify the output format and `--model` to specify the model. There
 are many other supported command line options. To see them all, run
 `mlx_whisper -h`.

whisper/mlx_whisper/cli.py

@@ -12,6 +12,18 @@ from .transcribe import transcribe
 from .writers import get_writer
 
 
+def get_media_files(path):
+    """Get all files in a directory recursively, excluding hidden files."""
+    path = pathlib.Path(path)
+    if not path.is_dir():
+        return []
+        
+    return [
+        file_path for file_path in path.rglob("*")
+        if file_path.is_file() and not any(p.startswith(".") for p in file_path.parts)
+    ]
+
+
 def build_parser():
     def optional_int(string):
         return None if string == "None" else int(string)
@@ -30,7 +42,7 @@ def build_parser():
         formatter_class=argparse.ArgumentDefaultsHelpFormatter
     )
 
-    parser.add_argument("audio", nargs="+", help="Audio file(s) to transcribe")
+    parser.add_argument("audio", nargs="+", type=str, help="Path(s) to audio file(s) or directories to transcribe")
 
     parser.add_argument(
         "--model",
@@ -239,7 +251,35 @@ def main():
 
             output_name = output_name or "content"
         else:
-            output_name = output_name or pathlib.Path(audio_obj).stem
+            path = pathlib.Path(audio_obj)
+            if path.is_dir():
+                media_files = get_media_files(path)
+                if not media_files:
+                    print(f"No media files found in directory: {path}")
+                    continue
+                
+                print(f"Found {len(media_files)} files in directory{path}")
+                response = input("Continue processing all files in target directory? [Y/n] ").strip()
+                if response.lower() in ['n', 'no']:
+                    continue
+                
+                if args.get("verbose"):
+                    print(f"Processing {len(media_files)} files in {path}...")
+                
+                for file_path in media_files:
+                    try:
+                        result = transcribe(
+                            str(file_path),
+                            path_or_hf_repo=path_or_hf_repo,
+                            **args,
+                        )
+                        writer(result, file_path.stem, **writer_args)
+                    except Exception as e:
+                        traceback.print_exc()
+                        print(f"Skipping {file_path} due to {type(e).__name__}: {str(e)}")
+                continue
+            output_name = output_name or path.stem
+
         try:
             result = transcribe(
                 audio_obj,