This tool is used to convert Advanced Audio Coding (aac) to Free Lossless Audio Codec (flac).

Advanced Audio Coding is an audio coding standard for lossy digital audio compression. Designed to be the successor of the MP3 format, AAC generally achieves better sound quality than MP3 at the same bit rate.

Free Lossless Audio Codec is an audio coding format for lossless compression of digital audio. Digital audio compressed by FLAC's algorithm can typically be reduced to 50–60% of its original size and decompressed to an identical copy of the original audio data.