I am attempting to automatically set H264 average bitrate when transcoding from MPEG2 using Nero. Currently, I consistently set the desired H264 average bitrate as a percetage of the MPEG2 average bitrate. For example, using 30% as the converted bitrate%: With a MPEG2 average bitrate of 5.04 Mbps, a bitrate of 1.5 Mbps is used for the H264 conversion.

Using a consistent 40% of orginal bitrate for the H264 bitrate creates a a great looking picture. A rate that is 30% of the original MPEG2 bit rate also looks good. I notice though, that movies that are Extra-Widescreen (with balck bars on a widescreen display) tend to look better than those that are full/ Widescreen (fill a widescreen display). Should my conversion consider the size of the picture? Doesn't the original bitrate reflect the original size of the picture?