and it is open source, but under a somewhat cumbersome license. For this
reason, most distributions do not compile FFmpeg with the FDK-AAC codec,
so you will need to compile FFmpeg yourself, or use a worse codec.
+FFmpeg `recommends <https://trac.ffmpeg.org/wiki/Encode/HighQualityAudio>`_
+their own native AAC encoder (simply called “aac”) in the absence of any
+external libraries.
For speed control, you can use::