This tool is used to convert MPEG-4 Audio (m4a) to Windows Media Audio (wma).

M4A is a file extension for an audio file encoded with advanced audio coding (AAC) which is a lossy compression. M4A was generally intended as the successor to MP3, which had not been originally designed for audio only but was layer III in an MPEG 1 or 2 video files.

Windows Media Audio is a series of audio codecs and their corresponding audio coding formats developed by Microsoft.