The Audio Video Interleave format interleaves audio and video streams in a Microsoft container format that supports many codecs but lacks modern streaming features. Converting to M4A produces a audio file that stores AAC-encoded audio in an MPEG-4 container, the standard audio format produced by iTunes and Apple devices. This extracts the audio stream from the video container, discarding the video track. The audio track is decoded and re-encoded (or stream-copied if the codec matches) while the video frames are discarded. This makes M4A the practical choice when the destination system requires it or when the original format is not supported by the target application. 1converter runs this conversion on the server: your file is uploaded encrypted over HTTPS, converted using trusted open-source libraries, and the output is held for 24 hours before automatic deletion.