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Cinema Físico
Known Participant
October 30, 2020
Answered

Difference between export VBR 1 pass and VBR 2 pass

  • October 30, 2020
  • 2 replies
  • 102306 views

 Hello what is the difference between export VBR 1 pass and VBR 2 pass? In which ocassion should I use VBR 1 pass and VBR 2 pass. 

 

Thank a lot

Correct answer RjL190365

As I stated in several other threads, nobody (hardware-wise) currently supports hardware acceleration for 2-pass VBR. Adobe has absolutely no control over this fact.

2 replies

Community Expert
November 5, 2020

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

Participant
March 26, 2021

I'm using Hardware acceleration and I have VBR 2 pass encoding option.

chrisw44157881
Inspiring
March 27, 2021

it may not be greyed out, but it won't be accelerated by the gpu.

Inspiring
November 5, 2020

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 🙂

 

Inspiring
November 5, 2020

To clarify:

2 pass VBR can give you the same quality as 1 pass VBR but at a lower datarate.

OR better quality than 1 pass VBR at the same datarate.

Ann Bens
Community Expert
Community Expert
November 5, 2020

Filesize = bitrate x duration.

Framesize is irrelevant.