Difference between export VBR 1 pass and VBR 2 pass

Also, I think you'll find, there is no option for 2 pass encoding if the export is using Hardware acceleration.

The first pass in a Variable Bitrate 2 pass encode is an analysis pass which looks at the video content of the program and looks for high motion, low motion and complexity. It then uses this analysis data on the second pass when actually encoding to assign more 'bits' to the scenes that have (say) high complexity motion and less 'bits' to (say) static scenes with no or little motion.

1 pass VBR just encodes 'on the fly' and can't encode frames 'knowing' what's further long in the program.

Effectively 2 pass VBR will give you better encodes at a slightly lower datarate than 1 pass VBR. Both usually provide better (or as good) encodes at significantly lower oevral file sizes than CBR (Constant Bitrate).

My advice. As long your encodes are set to reasonable datarates and you don't specifically need the absolute smallest possible encodes (file size) ... 2 pass VBR is generally not worth the extra time it takes*.

Hope this helps.

* I have one client that needs most encoded programs to be lower than 50MB in size. To hit this target we use 1280x720 instead of HD, VBR 2 pass, 1.4MBit average data rate and audio encoded mono at 96k ... but this is an outlier requirement and often they still look like crap but 2 pass makes them slightly better 🙂