
Given the following passage

"There are also open compression formats like Opus and Vorbis that are available free of charge and without any known patent restrictions. Some of the newer audio compression formats, such as AAC, WMA Pro and Vorbis, are free of some limitations inherent to the MP3 format that cannot be overcome by any MP3 encoder.",

answer the following question. Note that the answer is present within the text.

Question: What do the programs mentioned compress? 

MP3 format
