I want to process MKV files by mixing down the audio to 128kbps AAC on 2 channels while just copying video and subtitle tracks. So I run:
ffmpeg -i input.mkv -c:s copy -c:v copy -c:a aac -ab 128k -ac 2 output.mkv
However, MediaInfo shows that the audio bitrate is 224kbps.
What info should I trust?