OPUS is a audio format: it stores data in the OPUS format. M4V is a video format that stores data in the M4V format. 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 M4V natively or when the target platform only accepts M4V. 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.