The MPEG-4 Part 14 Video format packages H.264 or H.265 video with AAC audio in a container format widely supported across every platform and device. Converting to AAC produces a audio file that uses psychoacoustic lossy compression similar to MP3 but with improved efficiency, delivering better quality at the same bitrate. 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 AAC 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.