feat: encodage audio libopus VBR avec bitrate adaptatif

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

vid_convert.py

@@ -137,7 +137,13 @@ def extract_subs(file, track, lang):
 def convert_audio(file, track, volume_adj, channels, channel_layout, language, title):
     if channel_layout == "5.1(side)":
         channel_layout = "5.1"
-    codec = 'libfdk_aac -vbr 5'
+    if channels <= 2:
+        bitrate = "128k"
+    elif channels == 6:
+        bitrate = "320k"
+    else:
+        bitrate = "450k"
+    codec = f'libopus -vbr on -b:a {bitrate}'
     metadatas = f'-metadata language="{language}" -metadata title="{title}"'
     command = f'ffmpeg -loglevel error -i {file} -map 0:{track} -map_metadata -1 -vn -sn -c:a {codec} -mapping_family 1 -filter:a volume={volume_adj},aformat=channel_layouts={channel_layout} {metadatas} -y {file}_audio_{track}_{language}.mka'
     logging.debug(command)