What do CBR and VBR mean?
CBR stands for “Constant Bit Rate”, while VBR stands for “Variable Bit Rate”. Bit rate is a measurement of how much your MPEG-2 video is compressed. DVD video (not including audio or overhead) can be anywhere from 1.5Mbps (Megabits per second) to 9.2Mbps. When performing a CBR encode, all video is encoded to MPEG-2 at the same (constant) bitrate. When performing a VBR encode, the encoder intelligently varies the bitrate up and down as appropriate to the given video segment. VBR is more efficient, because different video segments are more or less complex than other segments. By using a low bitrate on some, the encoder can then using a higher bitrate on others. The idea is to only lower the bitrate when the video is easy enough to encode that you wont notice the higher compression. As the compressionist, you define how much the encoder is allowed to vary the bitrate (typically by entering a minimum, maximum, and average bitrate). In theory, you might think you should always use VBR becau
