Implement audio file compression

repub/media.py

@@ -0,0 +1,67 @@
+import logging
+import math
+
+import ffmpeg
+
+logger = logging.getLogger(__name__)
+
+
+def media_info(file_path):
+    return ffmpeg.probe(file_path)
+
+
+def bitrate(info) -> float:
+    try:
+        return int(info["format"]["bit_rate"])
+    except KeyError | ValueError:
+        return math.inf
+
+
+def format(info):
+    try:
+        return info["format"]["format_name"]
+    except KeyError | ValueError:
+        return None
+
+
+def compression_settings(input_file, settings):
+    info = media_info(input_file)
+    br = settings.get("REPUBLISHER_AUDIO_BITRATE", 96000)
+    fmt = settings.get("REPUBLISHER_AUDIO_FORMAT", "mp3")
+    if bitrate(info) <= br:
+        is_br = True
+    else:
+        is_br = False
+    if format(info) == fmt:
+        is_fmt = True
+    else:
+        is_fmt = False
+
+    if is_br and is_fmt:
+        return None
+
+    if is_br:
+        target_br = bitrate(info)
+    else:
+        target_br = br
+    return {"bitrate": target_br, "ext": "mp3"}
+
+
+def compress_audio(input_file, output_file_base, settings):
+    ext = settings["ext"]
+    br = settings["bitrate"]
+    output_file = f"{output_file_base}.{ext}"
+    try:
+        logger.info(f"Compressing audio {input_file} to {output_file} target_br={br}")
+        out, _ = (
+            ffmpeg.input(input_file)
+            .output(
+                output_file,
+                **{"b:a": f"{br}", "map": "0:a:0"},
+                loglevel="quiet",
+            )
+            .run()
+        )
+        return output_file
+    except ffmpeg.Error as e:
+        raise RuntimeError(f"Failed to load audio: {e.stderr.decode()}") from e