CAF (Core Audio Format) is a free audio container format developed by Apple and works on macOS 10.4 or later. It can also be opened on macOS 10.3 using QuickTime 7. Apart from audio, CAF can also hold multiple metadata such as file name, album name, composer, and more. It comes with a filename extension of .caf.
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According to YouTube, MP4 video format with AAC audio codec and H.264 video codec is most recommended. However, this platform is also compatible with formats such as MOV, AVI, WebM, FLV, 3GPP, WMV, and more. Also, keep in mind that the maximum file size for YouTube is 128GB or 12 hours of playtime. So, you can use a video editor like Wondershare UniConverter to compress before uploading videos to YouTube.
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