M4A is a audio format: it stores AAC-encoded audio in an MPEG-4 container, the standard audio format produced by iTunes and Apple devices. AVI is a video format that interleaves audio and video streams in a Microsoft container format that supports many codecs but lacks modern streaming features. This wraps the audio track in a video container, which some platforms require for upload. Metadata such as creation date and embedded colour profiles is preserved where the target format supports it. Converting between these two formats is common when the source application does not support AVI natively or when the target platform only accepts AVI. 1converter processes this conversion server-side using open-source tools. Files are transferred over HTTPS, converted on secure cloud servers, and automatically deleted after 24 hours.