VBR

Variable bitrate encoding sets a peak level at which the encoding bitrate cannot surpass, but allows the codec to use a lower amount of bandwidth or storage for less complex scenes or scenes with lower motion content. VBR often requires two passes over the content, with the first looking for potential areas to lower the bitrate, so it tends to be unsuited for live encodings. The advent of fragmented MP4 and segmentation, however, with its 2-10 second delay in streaming opens up the possibility of using VBR across large groups of pictures (GOPs).