M4V is a digital video container format developed by Apple Inc. It is pretty similar to the popular MP4 in terms of structure, but M4V files can sometimes be DRM protected. Today, M4V is the primary video format for iTunes Store videos and can multiplex together multiple audio and video data.
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HEVC (High Efficiency Video Coding), is a modern video compression standard developed as the successor to the standard H.264 (Advanced Video Coding). In comparison to H.264, this format offers up to 50% better data compression while providing improved video quality at a similar bitrate. Today, HEVC is used by over 40% of video developers, only second to AVC.