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In page Variable bitrate:

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MP3, WMA and AAC audio files can optionally be encoded in VBR, while Opus and Vorbis are encoded in VBR by default.[1][2][3] Variable bit rate encoding is also commonly used on MPEG-2 video, MPEG-4 Part 2 video (Xvid, DivX, etc.), MPEG-4 Part 10/H.264 video, Theora, Dirac and other video compression formats.[citation needed] Additionally, variable rate encoding is inherent in lossless compression schemes such as FLAC and Apple Lossless.[citation needed]