OPUS is a audio format: it stores data in the OPUS format. M4A is a audio format that stores AAC-encoded audio in an MPEG-4 container, the standard audio format produced by iTunes and Apple devices. This conversion changes the file's encoding, compression method, and supported feature set. 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 M4A natively or when the target platform only accepts M4A. 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.