VBR? CBR?
Once upon a time fierce debate raged over which is the optimum setting, so let’s explain why it was such an issue and what it means.
When CD ripping software calculates how the sound on your CD should be encoded into data files a significant amount of complex mathematics is applied. Using the skills of “psycho-acoustics” the software calculates the tiny bits of sound that can be compressed or simply deleted without reducing sound quality. Exactly how aggressive this set of calculations need be is determined by the bit rate setting. Indeed this is the prime determinant of final sound quality.
A further refinement of the calculations was to apply tougher criteria for example during quiet moments, rather than working to the same standard throughout the track. The first became known as Variable Bit Rate (VBR), the second Constant Bit Rate (CBR). Because more data could be discarded at key times in the track under VBR compared to CBR meant that Variable Bit Rate compression typically produced smaller files.
Smaller files? I write this on my MacBook with a 250Gb hard drive. Todays serious iPods sport 160Gb hard drives. Smaller file sizes?
Well, just a few years ago, iPods were just 5Gb - laptops were 20Gb or less, so smaller file sizes were to be prized. In today’s hardware climate you might ask if fiddly maths is worth the bother. To be frank my feeling is no, but as a service business we’ll provide VBR if that’s what a client wants.
