Difference: 2nd pass of 2pass vs 2nd pass of 3pass ?

[kotuwa]

What is the difference between the 2nd pass of the 2 pass and the 2nd pass of the 3 pass encode....

I did some samples and there, both are same if --slow-firstpass used in the first pass. (Didn't run crc etc, but file sizes are same upto the byte)

But if the --slow-firstpass is not used, then the output files are different.

Need to know what are the internal differences.


Idea is to do a 2-pass with stat files saved.
But in any case if I would want to do another pass, it is really good if it is a 3 pass... And to do that, using 3 pass from the beginning even though initial plan is to go with only 2 passes...

What lacks in the 2nd pas of 3 pass compared to the 2nd pass of 2 pass?
(It would be the answer to why having 3 options as 1, 2 and 3?... If it is same, no need of a 3rd one... But I need to know..)

Thank you very much!
:thanks:

[foxyshadis]

There is none. The only difference is that the stats file isn't updated.

[kotuwa]

There is none. The only difference is that the stats file isn't updated.
Updating the stat file seems to change little things, because the outputs are different...

If no difference, why there are 2 options as 2 and 3, while only one is needed!...

If --pass 2 given, encoder knows this is the final...
In --pass 3, it does not....
Is there any advantage telling that this is the final pass?
!

[ajp_anton]

Well, it's useful if you don't want the stats file to be updated. Like if you want to make multiple 2-pass encodes with slightly-different settings/bitrate from the same 1st pass stats file.

And the outputs might be different because of non-deterministic stuff caused by threading (?).