Music transcoder!!

music_transcoder/__main__.py

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+from dataclasses import dataclass
+import click
+import os
+import subprocess
+
+INPUT_FILE_EXTS_OPUSENC = [
+    ".flac",
+    ".wav",
+    ".aiff",
+]
+INPUT_FILE_EXTS_COPY = [
+    ".opus",
+    ".ogg",  # this can also contain FLAC (fry about it)
+    ".mp3",
+    ".m4a",
+]
+
+
+def get_opusenc_args(
+    input_path: str,
+    output_path: str,
+    bitrate: int = 192,
+) -> list[str]:
+    return [
+        "opusenc",
+        "--bitrate",
+        str(bitrate),
+        "--music",
+        input_path,
+        output_path,
+    ]
+
+
+@dataclass
+class InputFile:
+    filepath: str
+    relpath: str
+    relpath_noext: str
+    transcode: bool
+
+
+@click.option(
+    "--input-dir",
+    "-i",
+    type=click.Path(exists=True, dir_okay=True, file_okay=False, resolve_path=True),
+)
+@click.option(
+    "--output-dir",
+    "-o",
+    type=click.Path(
+        exists=False, dir_okay=True, file_okay=False, writable=True, resolve_path=True
+    ),
+)
+@click.command()
+def music_transcoder(input_dir, output_dir):
+    input_files: list[InputFile] = []
+
+    for dirpath, _, filenames in os.walk(input_dir):
+        for filename in filenames:
+            _, ext = os.path.splitext(filename)
+
+            transcode: bool
+            if ext in INPUT_FILE_EXTS_OPUSENC:
+                transcode = True
+            elif ext in INPUT_FILE_EXTS_COPY:
+                transcode = False
+            else:
+                print("[WARN] rejecting file:", dirpath, filename)
+                continue
+
+            filepath = os.path.join(dirpath, filename)
+            relpath = os.path.relpath(filepath, input_dir)
+            relpath_noext, _ = os.path.splitext(relpath)
+            input_files.append(
+                InputFile(
+                    filepath=filepath,
+                    relpath=relpath,
+                    relpath_noext=relpath_noext,
+                    transcode=transcode,
+                )
+            )
+
+    for input_file in input_files:
+        if input_file.transcode:
+            output_path = os.path.join(output_dir, input_file.relpath_noext + ".opus")
+        else:
+            output_path = os.path.join(output_dir, input_file.relpath)
+
+        if os.path.exists(output_path):
+            print("[WARN] skipping existing file", output_path)
+            continue
+
+        output_path_dir, _ = os.path.split(output_path)
+        os.makedirs(output_path_dir, exist_ok=True)
+
+        if not input_file.transcode:
+            print("[INFO] hardlinking lossy file →", output_path)
+            os.link(input_file.filepath, output_path)
+            continue
+
+        print("[INFO] transcoding lossless file →", output_path)
+        opusenc_args = get_opusenc_args(input_file.filepath, output_path)
+        subprocess.run(opusenc_args, check=True)
+
+
+if __name__ == "__main__":
+    music_transcoder()